check point (bc i don't trust googledrive sync yet)

* IsSocketStateOpen
* IsClosedProperly

.editorconfig

@@ -207,17 +207,23 @@ dotnet_naming_symbols.parameters.applicable_accessibilities = public,internal,pr
 dotnet_naming_symbols.private_symbols.applicable_kinds = property,method,field,event,delegate
 dotnet_naming_symbols.private_symbols.applicable_accessibilities = protected,private
 
+# local symbols
+dotnet_naming_symbols.local_symbols.applicable_kinds = local
+
+# parameter symbols
+dotnet_naming_symbols.parameter_symbols.applicable_kinds = parameter
+
 # Naming styles
 
-dotnet_naming_style.snake_case.required_prefix =
-dotnet_naming_style.snake_case.required_suffix =
-dotnet_naming_style.snake_case.word_separator = _
-dotnet_naming_style.snake_case.capitalization = all_lower
+dotnet_naming_style.pascal_case.required_prefix =
+dotnet_naming_style.pascal_case.required_suffix =
+dotnet_naming_style.pascal_case.word_separator =
+dotnet_naming_style.pascal_case.capitalization = pascal_case
 
-dotnet_naming_style.private_snake_case.required_prefix = _
-dotnet_naming_style.private_snake_case.required_suffix =
-dotnet_naming_style.private_snake_case.word_separator = _
-dotnet_naming_style.private_snake_case.capitalization = all_lower
+dotnet_naming_style.camel_case.required_prefix =
+dotnet_naming_style.camel_case.required_suffix =
+dotnet_naming_style.camel_case.word_separator =
+dotnet_naming_style.camel_case.capitalization = camel_case
 
 dotnet_naming_style.user_types.required_prefix =
 dotnet_naming_style.user_types.required_suffix =
@@ -229,6 +235,10 @@ dotnet_naming_style.interface.required_suffix =
 dotnet_naming_style.interface.word_separator =
 dotnet_naming_style.interface.capitalization = pascal_case
 
+dotnet_naming_style.local.capitalization = camel_case
+
+dotnet_naming_style.parameter.capitalization = camel_case
+
 # rules
 dotnet_naming_rule.user_types.symbols = user_types
 dotnet_naming_rule.user_types.style = user_types
@@ -238,14 +248,18 @@ dotnet_naming_rule.interfaces.symbols = interface
 dotnet_naming_rule.interfaces.style = interface_style
 dotnet_naming_rule.interfaces.severity = suggestion
 
-dotnet_naming_rule.public_members_snake_case.symbols = public_symbols
-dotnet_naming_rule.public_members_snake_case.style = snake_case
-dotnet_naming_rule.public_members_snake_case.severity = suggestion
+dotnet_naming_rule.public_members.symbols = public_symbols
+dotnet_naming_rule.public_members.style = pascal_case
+dotnet_naming_rule.public_members.severity = suggestion
 
-dotnet_naming_rule.private_members_snake_case.symbols = private_symbols
-dotnet_naming_rule.private_members_snake_case.style = private_snake_case
-dotnet_naming_rule.private_members_snake_case.severity = suggestion
+dotnet_naming_rule.private_members.symbols = private_symbols
+dotnet_naming_rule.private_members.style = camel_case
+dotnet_naming_rule.private_members.severity = suggestion
 
-dotnet_naming_rule.parameters.symbols = parameters
-dotnet_naming_rule.parameters.style = snake_case
+dotnet_naming_rule.variables_are_camel_case.severity = suggestion
+dotnet_naming_rule.variables_are_camel_case.symbols = local_symbols
+dotnet_naming_rule.variables_are_camel_case.style = local
+
+dotnet_naming_rule.parameters.symbols = parameter_symbols
+dotnet_naming_rule.parameters.style = parameter
 dotnet_naming_rule.parameters.severity = suggestion

.gitignore

@@ -47,13 +47,13 @@ trace_data/
 /src/.clang-format
 /src/server/sparkd/cmds/spartan/analysis/.ipynb_checkpoints
 /src/server/sparkd/cmds/spartan/analysis/data
-*.tmp/*
-/.venv*/*
+.tmp/
+.venv*/
 .cache/
 /src/Spark.Admin.WebApp/tsconfig.*.g.json
 /src/Spark.Admin.WebApp/src/bin/
 **/CMakeDeps.cmake
 **/CMakeDeps_win.cmake
-**/devcontainer.json
+**/.devcontainer
 *.Generated.cs
 *.lst

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "externals"]
 	path = externals
-	url = git@bitbucket.org:bluetradesys/externals.git
+	url = https://x-token-auth:ATCTT3xFfGN0h_ENnUSfEAIzbfVzkQPLG26cIli50MtcTwZ7VEc8lin5tJYqibjlBJ9PM9R642Ra5GjiL52TBfbO8KeUBT0UoMT7gLQHL2Y1TkW9yZr6NkvsoDkSl49DeD4Ijiu4_0u4qEm4oMVDDg2_fB059-uOWOo7ZL94tGZET8CSVpFIGvs=B0E03660@bitbucket.org/bluetradesys/externals.git
 [submodule "vcpkg"]
 	path = vcpkg
 	url = https://github.com/microsoft/vcpkg.git

.gitpod.yml

@@ -0,0 +1,49 @@
+# This configuration file was automatically generated by Gitpod.
+# Please adjust to your needs (see https://www.gitpod.io/docs/introduction/learn-gitpod/gitpod-yaml)
+# and commit this file to your remote git repository to share the goodness with others.
+
+# Learn more from ready-to-use templates: https://www.gitpod.io/docs/introduction/getting-started/quickstart
+
+image: gitpod/workspace-dotnet-8
+tasks:
+  - name: Install Deps
+    init: |
+      (
+        set -e
+        sudo install-packages rapidjson-dev
+        sudo install-packages libssh2-1-dev
+        sudo install-packages openssh-server
+        sudo install-packages liblttng-ust-dev
+        sudo install-packages libpcap0.8-dev
+        sudo install-packages ccache
+        sudo ln -s $(which ccache) /usr/local/bin/clang
+        sudo ln -s $(which ccache) /usr/local/bin/clang++
+        sudo ln -s $(which ccache) /usr/local/bin/clang-17
+        sudo ln -s $(which ccache) /usr/local/bin/clang++-17
+        sudo ln -s $(which ccache) /usr/local/bin/gcc
+        sudo ln -s $(which ccache) /usr/local/bin/g++
+        sudo ln -s $(which ccache) /usr/local/bin/gcc-12
+        sudo ln -s $(which ccache) /usr/local/bin/g++-12
+        if [ -e externals/src/emumba/install_emumba-deribit-connector.sh ]; then
+          externals/src/emumba/install_emumba-deribit-connector.sh
+        fi
+      )
+  - name: Setup Python venv
+    init: |
+      python -m pip install --upgrade pip
+      python -m venv .venv
+      . .venv/bin/activate
+      python -m pip install --upgrade pip
+      pip install -r requirements.txt
+
+ports:
+  - name: sparkd config
+    port: 8000
+    onOpen: notify
+  - name: sparkd bus
+    port: 8001
+
+gitConfig:
+  alias.st: "status"
+  status.short: "true"
+  core.pager: "less -FXRS"

CMakePresets.json

@@ -29,8 +29,8 @@
         "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/vcpkg/scripts/buildsystems/vcpkg.cmake",
         "EXTERNALS_ROOT": "${sourceDir}/externals/windows",
         "CONFIG_DEFAULTS_PATH": "config/profiles/default/*.conf",
-        "DOTNET_BINARY_DIR": "${sourceDir}/build/$<CONFIG>/bin/net7.0",
-        "DOTNET_WINDOWS_BINARY_DIR": "${sourceDir}/build/$<CONFIG>/bin/net7.0-windows"
+        "DOTNET_BINARY_DIR": "${sourceDir}/build/$<CONFIG>/bin/net8.0",
+        "DOTNET_WINDOWS_BINARY_DIR": "${sourceDir}/build/$<CONFIG>/bin/net8.0-windows"
       }
     },
 
@@ -197,7 +197,7 @@
         "CMAKE_CXX_FLAGS_RELEASE": "-fPIC -Wall -pedantic -Wextra -Werror -Wno-missing-braces -Wno-ignored-qualifiers --std=c++20 -fdiagnostics-color -fno-omit-frame-pointer -DNDEBUG -O3",
         "CMAKE_INSTALL_PREFIX": "${sourceDir}/install/${presetName}",
         "CONFIG_DEFAULTS_PATH": "config/profiles/default/*.conf",
-        "DOTNET_BINARY_DIR": "${sourceDir}/build/$<CONFIG>/bin/net7.0"
+        "DOTNET_BINARY_DIR": "${sourceDir}/build/$<CONFIG>/bin/net8.0"
       }
     },
 

docker/sparkd/dev/Dockerfile

@@ -1,59 +1,65 @@
-FROM ubuntu:latest
+FROM ubuntu:22.04
 
 ARG DEBIAN_FRONTEND=noninteractive
-ENV TZ=America/New_York
 
-# light deps (should be quick to download/install)
+# Foundational Deps
 RUN apt-get update && apt-get install -y \
+    build-essential \
     ca-certificates \
     curl \
     gnupg \
     liblttng-ust-dev \
     libpcap0.8-dev \
+    libssh2-1-dev \
     locales \
-    ninja-build \
+    openssh-server \
     software-properties-common \
-    sqlite3 \
+    sudo \
     tzdata
 
-# clang
-RUN apt-get update && apt-get install -y \
-    clang-13 \
-    clang-format-13 \
-    clangd-13 \
-    clang-15 \
-    clang-format-15 \
-    clangd-15
+# Clang 17
+RUN curl -fsSL https://apt.llvm.org/llvm-snapshot.gpg.key 2> /dev/null \
+    | gpg --dearmor - \
+    | tee /usr/share/keyrings/llvm-snapshot.gpg > /dev/null \
+    && echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg] http://apt.llvm.org/jammy/ llvm-toolchain-jammy-17 main" \
+    | tee -a "/etc/apt/sources.list.d/llvm.list" \
+    && apt-get update \
+    && apt-get install -y \
+    clang-17 \
+    clang-format-17 \
+    clangd-17
 
-# g++
+# G++
 RUN apt-get update && apt-get install -y \
-    g++-11 \
-    g++-12
+    g++
 
-# python
+# Ninja
+RUN apt-get update && apt-get install -y \
+    ninja-build
+
+# CMake
+RUN curl -fsSL https://apt.kitware.com/keys/kitware-archive-latest.asc 2> /dev/null \
+    | gpg --dearmor - \
+    | tee /usr/share/keyrings/kitware-archive-keyring.gpg > /dev/null \
+    && echo "deb [signed-by=/usr/share/keyrings/kitware-archive-keyring.gpg] https://apt.kitware.com/ubuntu/ $(lsb_release -cs) main" \
+    | tee /etc/apt/sources.list.d/kitware.list > /dev/null \
+    && apt-get update \
+    && apt-get install -y cmake
+
+# Dotnet
+RUN curl -fsSLO "https://packages.microsoft.com/config/ubuntu/$(lsb_release -rs)/packages-microsoft-prod.deb" \
+    && dpkg -i packages-microsoft-prod.deb \
+    && rm packages-microsoft-prod.deb \
+    && apt-get update \
+    && apt-get install -y dotnet-sdk-8.0
+
+# Python
 RUN apt-get update && apt-get install -y \
     python3-pip \
     python3-venv \
     && python3 -m pip install --upgrade pip
 
-# dotnet
-RUN apt-get update && apt-get install -y \
-    dotnet7
-
-# ssh
-RUN apt-get update && apt-get install -y \
-    libssh2-1-dev \
-    openssh-server
-
-# cmake
-RUN \
-    curl -fsSL https://apt.kitware.com/keys/kitware-archive-latest.asc 2> /dev/null \
-    | gpg --dearmor - | tee /etc/apt/trusted.gpg.d/kitware.gpg > /dev/null \
-    && apt-add-repository "deb https://apt.kitware.com/ubuntu/ $(lsb_release -cs) main" \
-    && apt-get update \
-    && apt-get install -y cmake
-
-# node
+# Node
 ARG node_major=18
 RUN mkdir -p /etc/apt/keyrings \
     && curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key \
@@ -63,54 +69,35 @@ RUN mkdir -p /etc/apt/keyrings \
     && apt-get update \
     && apt-get install -y nodejs
 
-# ccache is done here so that ccache sees clang++ installed, not clang-10
+# Sqlite3
 RUN apt-get update && apt-get install -y \
-    ccache 
+    sqlite3
 
-# emumba (light deps)
-RUN apt-get update && apt-get install -y \
-    build-essential \
-    doxygen \
-    python3-sphinx \
-    graphviz \
-    libgtest-dev \
-    libssl-dev \
-    rapidjson-dev \
-    zlib1g-dev \
-    pkg-config
-
-# emumba (boost)
-RUN apt-get update && apt-get install -y \
-    libboost-filesystem-dev \
-    libboost-program-options-dev \
-    libboost-test-dev \
-    libboost-date-time-dev
-
-# dev utils
+# Dev Utils (install last so they can be added/removed with minimal rebuild)
 RUN apt-get update && apt-get install -y \ 
+    ccache \
     fish \
+    gdb \
     git-all \
-    sudo \
-    vim \
-    wget
+    vim
 
-# set up default executables (update-alternatives)
-RUN \
-    update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-13 100; \
-    update-alternatives --install /usr/bin/clang clang /usr/bin/clang-13 100; \
-    update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-13 100; \
-    update-alternatives --install /usr/bin/clangd clangd /usr/bin/clangd-13 100; \
-    update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-11 100; \
-    update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-11 100
+# Set up default executables (update-alternatives)
+RUN update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-17 100; \
+    update-alternatives --install /usr/bin/clang clang /usr/bin/clang-17 100; \
+    update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-17 100; \
+    update-alternatives --install /usr/bin/clangd clangd /usr/bin/clangd-17 100; \
+    update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-12 100; \
+    update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-12 100
 
 # Add compiler symlinks for ccache 
-RUN \
-    ln -s /usr/bin/ccache /usr/local/bin/clang; \
+RUN ln -s /usr/bin/ccache /usr/local/bin/clang; \
     ln -s /usr/bin/ccache /usr/local/bin/clang++; \
     ln -s /usr/bin/ccache /usr/local/bin/clang-13; \
     ln -s /usr/bin/ccache /usr/local/bin/clang++-13; \
     ln -s /usr/bin/ccache /usr/local/bin/clang-15; \
     ln -s /usr/bin/ccache /usr/local/bin/clang++-15; \
+    ln -s /usr/bin/ccache /usr/local/bin/clang-17; \
+    ln -s /usr/bin/ccache /usr/local/bin/clang++-17; \
     ln -s /usr/bin/ccache /usr/local/bin/gcc; \
     ln -s /usr/bin/ccache /usr/local/bin/g++; \
     ln -s /usr/bin/ccache /usr/local/bin/gcc-11; \
@@ -124,8 +111,7 @@ ARG docker_user="bts"
 ARG docker_uid="1000"
 ARG docker_pass="bts"
 
-RUN \
-    groupadd -g "$docker_uid" "$docker_user" \
+RUN groupadd -g "$docker_uid" "$docker_user" \
     && useradd \
     -m \
     -u "$docker_uid" \

docker/sparkd/dev/devcontainer.json

@@ -1,6 +1,7 @@
 {
   "image": "bluetradingsystems/sparkd-dev:latest",
-  "initializeCommand": "${localWorkspaceFolder}/docker/sparkd/dev/devcontainer_initialize.sh",
+  // Creates local dir to mount to HOME in docker 
+  "initializeCommand": "mkdir -p ${localEnv:HOME}/.bts/devcontainer-mounts/${devcontainerId}",
   "hostRequirements": {
     "memory": "4gb",
     "storage": "6gb"
@@ -27,6 +28,6 @@
     "8003:8003"
   ],
   "mounts": [
-    "source=${localEnv:HOME}/.sparkd-dev/mounts/sparkd-dev,target=/home/bts,type=bind"
+    "source=${localEnv:HOME}/.bts/devcontainer-mounts/${devcontainerId},target=/home/bts,type=bind"
   ]
 }

docker/sparkd/dev/devcontainer_initialize.sh

@@ -1,3 +0,0 @@
-#!/usr/bin/env bash
-
-mkdir -p "$HOME/.sparkd-dev/mounts/sparkd-dev"

playground-1.mongodb.js

@@ -0,0 +1,45 @@
+/* global use, db */
+// MongoDB Playground
+// To disable this template go to Settings | MongoDB | Use Default Template For Playground.
+// Make sure you are connected to enable completions and to be able to run a playground.
+// Use Ctrl+Space inside a snippet or a string literal to trigger completions.
+// The result of the last command run in a playground is shown on the results panel.
+// By default the first 20 documents will be returned with a cursor.
+// Use 'console.log()' to print to the debug output.
+// For more documentation on playgrounds please refer to
+// https://www.mongodb.com/docs/mongodb-vscode/playgrounds/
+
+// Select the database to use.
+use('mongodbVSCodePlaygroundDB');
+
+// Insert a few documents into the sales collection.
+db.getCollection('sales').insertMany([
+    { 'item': 'abc', 'price': 10, 'quantity': 2, 'date': new Date('2014-03-01T08:00:00Z') },
+    { 'item': 'jkl', 'price': 20, 'quantity': 1, 'date': new Date('2014-03-01T09:00:00Z') },
+    { 'item': 'xyz', 'price': 5, 'quantity': 10, 'date': new Date('2014-03-15T09:00:00Z') },
+    { 'item': 'xyz', 'price': 5, 'quantity': 20, 'date': new Date('2014-04-04T11:21:39.736Z') },
+    { 'item': 'abc', 'price': 10, 'quantity': 10, 'date': new Date('2014-04-04T21:23:13.331Z') },
+    { 'item': 'def', 'price': 7.5, 'quantity': 5, 'date': new Date('2015-06-04T05:08:13Z') },
+    { 'item': 'def', 'price': 7.5, 'quantity': 10, 'date': new Date('2015-09-10T08:43:00Z') },
+    { 'item': 'abc', 'price': 10, 'quantity': 5, 'date': new Date('2016-02-06T20:20:13Z') },
+]);
+
+// Run a find command to view items sold on April 4th, 2014.
+const salesOnApril4th = db.getCollection('sales').find({
+    date: { $gte: new Date('2014-04-04'), $lt: new Date('2014-04-05') }
+}).count();
+
+// Print a message to the output window.
+console.log(`${salesOnApril4th} sales occurred in 2014.`);
+
+// Here we run an aggregation and open a cursor to the results.
+// Use '.toArray()' to exhaust the cursor to return the whole result set.
+// You can use '.hasNext()/.next()' to iterate through the cursor page by page.
+db.getCollection('sales').aggregate([
+    // Find all of the sales that occurred in 2014.
+    { $match: { date: { $gte: new Date('2014-01-01'), $lt: new Date('2015-01-01') } } },
+    // Group the total sales for each product.
+    { $group: { _id: '$item', totalSaleAmount: { $sum: { $multiply: ['$price', '$quantity'] } } } }
+]);
+
+

src/DataStreamSuite/ArithmeticExpressions/ArithmeticExpressions.csproj

@@ -1,14 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
     <PackageReference Include="Google.Protobuf" Version="3.24.3" />
-    <PackageReference Include="YaccLexTools" Version="1.2.0" />
+    <PackageReference Include="YaccLexTools" Version="1.2.2" />
   </ItemGroup>
 
   <ItemGroup>

src/DataStreamSuite/BaseUtilities/BaseUtilities.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>

src/DataStreamSuite/BlueRegistry/BlueRegistry.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0-windows</TargetFramework>
+    <TargetFramework>net8.0-windows</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <UseWindowsForms>true</UseWindowsForms>

src/DataStreamSuite/BooleanExpressions/BooleanExpressions.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>

src/DataStreamSuite/Bts.ColumnExpressions/Bts.ColumnExpressions.csproj

@@ -0,0 +1,24 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="YaccLexTools" Version="1.2.2" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\DataStreamCore\DataStreamCore.csproj" />
+    <ProjectReference Include="..\ExpressionCore\ExpressionCore.csproj" />
+    <ProjectReference Include="..\..\client\spark_core\spark_core.csproj" />
+  </ItemGroup>
+
+  <ItemGroup Label="ColumnExpression">
+    <Scanner Include="ColumnExpressionTokens.lex" />
+    <Parser Include="ColumnExpressionGrammar.y" />
+  </ItemGroup>
+
+</Project>

src/DataStreamSuite/Bts.ColumnExpressions/ColumnExpression.cs

@@ -0,0 +1,62 @@
+namespace Bts.ColumnExpressions;
+
+public class ColumnExpression {
+   public ColumnExpression(string name, Type? type = null, object? value = null) {
+      Name = name;
+      Type = type
+         ?? value?.GetType()
+         ?? throw new ArgumentException(
+            "Type must be specified explicitly when value is null", nameof(type));
+      Value = value
+         ?? DBNull.Value;
+   }
+
+   public string Name { get; }
+
+   public Type Type { get; }
+
+   public object Value { get; }
+
+   public static ColumnExpression Create<T>(string name, T value, Type? type = null) {
+      // Try to convert value to 'type' to verify they are compatible
+      // Note: Can't use `System.Type.IsAssignableFrom` because it doesn't
+      // account for implicit conversions (e.g., int -> long), just inheritance.
+      if (type is not null && !ConvertUtils.try_convert(type, value, out _)) {
+         throw new ArgumentException(
+            $"Type '{type}' is not assignable from value type '{value?.GetType()}'");
+      }
+      return new(name, type ?? typeof(T), value);
+   }
+
+   internal static Type ParseType(string typeId) {
+      return Candidates().ExceptNull().FirstOrDefault() ??
+         throw new ArgumentException($"Failed to parse Type from '{typeId}'", nameof(typeId));
+
+      IEnumerable<Type?> Candidates() {
+         if (typeId.Length == 0) {
+            yield break;
+         }
+         yield return Type.GetType(typeId);
+         yield return Type.GetType($"System.{typeId}");
+         if (typeId.Length > 1) {
+            yield return Type.GetType($"System.{char.ToUpper(typeId[0]) + typeId[1..]}");
+         }
+         yield return typeId.ToLower() switch {
+            "float64" or "double" or "real64" or "number" => typeof(double),
+            "float32" or "single" or "real32" or "real" or "float" => typeof(float),
+            "int16" or "short" or "integer16" or "signed16" => typeof(short),
+            "int32" or "int" or "integer" or "integer32" or "signed" => typeof(int),
+            "int64" or "long" or "integer64" or "signed64" => typeof(long),
+            "uint16" or "ushort" or "unsigned16" => typeof(ushort),
+            "uint32" or "uint" or "unsigned" => typeof(uint),
+            "uint64" or "ulong" or "unsigned64" => typeof(ulong),
+            "char" => typeof(char),
+            "byte" or "uint8" => typeof(byte),
+            "bool" or "boolean" => typeof(bool),
+            "string" or "text" => typeof(string),
+            "date" or "datetime" => typeof(DateTime),
+            _ => null
+         };
+      }
+   }
+}

src/DataStreamSuite/Bts.ColumnExpressions/ColumnExpressionGrammar.y

@@ -0,0 +1,49 @@
+%namespace Bts.ColumnExpressions
+%partial
+%visibility internal
+%tokentype ColumnExpressionToken
+%parsertype ColumnExpressionParser
+
+%union {
+   public int Integer;
+   public double Real;
+   public bool Boolean;
+   public string String;
+   public string Identifier;
+   public string TypeId;
+   public DateTime DateTime;
+   public Tuple<string, Type> ColumnDefinition;
+   public ColumnExpression ColumnExpression;
+   public ImmutableList<ColumnExpression> ColumnExpressions;
+}
+
+%token BOOLEAN_CONSTANT, INTEGER_CONSTANT, REAL_CONSTANT, DATE_TIME_CONSTANT, STRING_CONSTANT
+%token IDENTIFIER, EQUALS, TYPE_ID, OF_TYPE
+
+%nonassoc EQUALS
+
+%type <ColumnDefinition> ColumnDefinition
+%type <ColumnExpression> ColumnExpression
+%type <ColumnExpressions> ColumnExpressions
+
+%%
+
+ColumnExpressions :
+   ColumnExpression { $$ = ImmutableList.CreateRange(new[] { $1 }); }
+   | ColumnExpressions ColumnExpression { $$ = $1.Add($2); }
+   ;
+
+ColumnExpression :
+   ColumnDefinition EQUALS INTEGER_CONSTANT { $$ = ColumnExpression.Create($1.Item1, $3.Integer, $1.Item2); }
+   | ColumnDefinition EQUALS REAL_CONSTANT { $$ = ColumnExpression.Create($1.Item1, $3.Real, $1.Item2); }
+   | ColumnDefinition EQUALS DATE_TIME_CONSTANT { $$ = ColumnExpression.Create($1.Item1, $3.DateTime, $1.Item2); }
+   | ColumnDefinition EQUALS BOOLEAN_CONSTANT { $$ = ColumnExpression.Create($1.Item1, $3.Boolean, $1.Item2); }
+   | ColumnDefinition EQUALS STRING_CONSTANT { $$ = ColumnExpression.Create($1.Item1, $3.String, $1.Item2); }
+   | ColumnDefinition { $$ = new($1.Item1, $1.Item2); }
+   ;
+
+ColumnDefinition :
+   IDENTIFIER { $$ = new($1.Identifier, null); }
+   | IDENTIFIER OF_TYPE IDENTIFIER { $$ = new($1.Identifier, ColumnExpression.ParseType($3.Identifier)); }
+   | IDENTIFIER OF_TYPE TYPE_ID { $$ = new($1.Identifier, ColumnExpression.ParseType($3.TypeId)); }
+   ; 

src/DataStreamSuite/Bts.ColumnExpressions/ColumnExpressionInterpreter.cs

@@ -0,0 +1,18 @@
+namespace Bts.ColumnExpressions;
+
+using System.IO;
+using System.Text;
+
+public class ColumnExpressionInterpreter {
+   public static IList<ColumnExpression> Evaluate(Stream stream) {
+      var parser = new ColumnExpressionParser();
+      var res = parser.Parse(stream);
+      return res?.ColumnExpressions ?? ImmutableList<ColumnExpression>.Empty.Add(
+         res?.ColumnExpression ?? throw new Exception("Failed to parse column(s) expression"));
+   }
+
+   public static IList<ColumnExpression> Evaluate(string str) {
+      using var ms = new MemoryStream(Encoding.Default.GetBytes(str));
+      return Evaluate(ms);
+   }
+}

src/DataStreamSuite/Bts.ColumnExpressions/ColumnExpressionParser.cs

@@ -0,0 +1,18 @@
+namespace Bts.ColumnExpressions;
+
+using System.Text;
+
+partial class ColumnExpressionParser {
+   public ColumnExpressionParser() : base(null) { }
+
+   public ValueType? Parse(string s) {
+      using var ms = new MemoryStream(Encoding.Default.GetBytes(s));
+      return Parse(ms);
+   }
+
+   public ValueType? Parse(Stream stream) {
+      Scanner = new ColumnExpressionScanner(stream);
+      Parse();
+      return CurrentSemanticValue;
+   }
+}

src/DataStreamSuite/Bts.ColumnExpressions/ColumnExpressionScanner.cs

@@ -0,0 +1,9 @@
+namespace Bts.ColumnExpressions;
+
+partial class ColumnExpressionScanner {
+   public override void yyerror(string format, params object[] args) {
+      base.yyerror(format, args);
+      Console.WriteLine(format, args);
+      Console.WriteLine();
+   }
+}

src/DataStreamSuite/Bts.ColumnExpressions/ColumnExpressionTokens.lex

@@ -0,0 +1,85 @@
+%namespace Bts.ColumnExpressions
+%scannertype ColumnExpressionScanner
+%visibility internal
+%tokentype ColumnExpressionToken
+
+%option stack, minimize, parser, verbose, persistbuffer, noembedbuffers 
+
+/* Literal Constants */
+Letter                   [a-zA-Z]
+BooleanConstant          true|false
+StringConstant           '([^\'\\]*|\\.)*'
+DateTimeConstant         ([1-9]|'10'|'11'|'12')\/([1-9]|([1-2][0-9])|'30'|'31')\/[0-9][0-9][0-9]*
+IntegerConstant          -?[0-9]+
+NullConstant             'null'
+RealConstant             -?[0-9]+\.[0-9]+
+
+/* Relational Operators */
+Equals                   =
+OfType                   /
+
+Identifier               {Letter}({Letter}*[0-9]*_*)*
+NamespacePrefix          {Identifier}\.
+TypeId                   {NamespacePrefix}*{Identifier}
+
+/* Utility Tokens */
+OpenParenthesis          \(
+CloseParenthesis         \)
+Comma                    ,
+QuoteOpen                \[
+QuoteClose               \]
+
+/* Comments */
+LineComment \/\/[^\n\r]*(\n|\r|\r\n)
+
+%%
+
+{Equals} {
+   return (int)ColumnExpressionToken.EQUALS;
+}
+
+{OfType} {
+   return (int)ColumnExpressionToken.OF_TYPE;
+}
+
+{StringConstant} {
+   yylval.String = yytext.Substring(1, yytext.Length - 2).Replace(@"\'","'");
+   return (int)ColumnExpressionToken.STRING_CONSTANT;
+}
+
+{BooleanConstant} {
+   yylval.Boolean = yytext.ToLower() switch {
+      "true" => true,
+      "false" => false,
+      _ => throw new Exception(
+         string.Format("Expected yytext to be 'true' or 'false' (actually '{0}')", yytext))
+   };
+   return (int)ColumnExpressionToken.BOOLEAN_CONSTANT;
+}
+
+{DateTimeConstant} {
+   yylval.DateTime = DateTime.Parse(yytext);
+   return (int)ColumnExpressionToken.DATE_TIME_CONSTANT;
+}
+
+{IntegerConstant} {
+   yylval.Integer = int.Parse(yytext);
+   return (int)ColumnExpressionToken.INTEGER_CONSTANT;
+}
+
+{RealConstant} {
+   yylval.Real = double.Parse(yytext);
+   return (int)ColumnExpressionToken.REAL_CONSTANT;
+}
+
+{Identifier} {
+   yylval.Identifier = yytext;
+   return (int)ColumnExpressionToken.IDENTIFIER;
+}
+
+{TypeId} {
+   yylval.TypeId = yytext;   
+   return (int)ColumnExpressionToken.TYPE_ID;
+}
+
+%%

src/DataStreamSuite/Bts.ColumnExpressions/GplexBuffers.cs

@@ -0,0 +1,720 @@
+// ==============================================================
+// <auto-generated>
+// This code automatically produced from an embedded resource.
+// Do not edit this file, or it will become incompatible with 
+// the specification from which it was generated.
+// </auto-generated>
+// ==============================================================
+
+using System;
+using System.IO;
+using System.Text;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.Serialization;
+using System.Globalization;
+
+namespace QUT.GplexBuffers
+{
+// Code copied from GPLEX embedded resource
+    [Serializable]
+    internal class BufferException : Exception
+    {
+        public BufferException() { }
+        public BufferException(string message) : base(message) { }
+        public BufferException(string message, Exception innerException)
+            : base(message, innerException) { }
+        protected BufferException(SerializationInfo info, StreamingContext context)
+            : base(info, context) { }
+    }
+
+    internal abstract class ScanBuff
+    {
+        private string fileNm;
+
+        public const int EndOfFile = -1;
+        public const int UnicodeReplacementChar = 0xFFFD;
+
+        public bool IsFile { get { return (fileNm != null); } }
+        public string FileName { get { return fileNm; } set { fileNm = value; } }
+
+        public abstract int Pos { get; set; }
+        public abstract int Read();
+        public virtual void Mark() { }
+
+        public abstract string GetString(int begin, int limit);
+
+        public static ScanBuff GetBuffer(string source)
+        {
+            return new StringBuffer(source);
+        }
+
+        public static ScanBuff GetBuffer(IList<string> source)
+        {
+            return new LineBuffer(source);
+        }
+
+#if (!NOFILES)
+        public static ScanBuff GetBuffer(Stream source)
+        {
+            return new BuildBuffer(source);
+        }
+
+#if (!BYTEMODE)
+        public static ScanBuff GetBuffer(Stream source, int fallbackCodePage)
+        {
+            return new BuildBuffer(source, fallbackCodePage);
+        }
+#endif // !BYTEMODE
+#endif // !NOFILES
+    }
+
+    #region Buffer classes
+
+    // ==============================================================
+    // =====  Definitions for various ScanBuff derived classes   ====
+    // ==============================================================
+    // ===============         String input          ================
+    // ==============================================================
+
+    /// <summary>
+    /// This class reads characters from a single string as
+    /// required, for example, by Visual Studio language services
+    /// </summary>
+    sealed class StringBuffer : ScanBuff
+    {
+        string str;        // input buffer
+        int bPos;          // current position in buffer
+        int sLen;
+
+        public StringBuffer(string source)
+        {
+            this.str = source;
+            this.sLen = source.Length;
+            this.FileName = null;
+        }
+
+        public override int Read()
+        {
+            if (bPos < sLen) return str[bPos++];
+            else if (bPos == sLen) { bPos++; return '\n'; }   // one strike, see new line
+            else { bPos++; return EndOfFile; }                // two strikes and you're out!
+        }
+
+        public override string GetString(int begin, int limit)
+        {
+            //  "limit" can be greater than sLen with the BABEL
+            //  option set.  Read returns a "virtual" EOL if
+            //  an attempt is made to read past the end of the
+            //  string buffer.  Without the guard any attempt 
+            //  to fetch yytext for a token that includes the 
+            //  EOL will throw an index exception.
+            if (limit > sLen) limit = sLen;
+            if (limit <= begin) return "";
+            else return str.Substring(begin, limit - begin);
+        }
+
+        public override int Pos
+        {
+            get { return bPos; }
+            set { bPos = value; }
+        }
+
+        public override string ToString() { return "StringBuffer"; }
+    }
+
+    // ==============================================================
+    //  The LineBuff class contributed by Nigel Horspool, 
+    //  nigelh@cs.uvic.cs
+    // ==============================================================
+
+    sealed class LineBuffer : ScanBuff
+    {
+        IList<string> line;    // list of source lines from a file
+        int numLines;          // number of strings in line list
+        string curLine;        // current line in that list
+        int cLine;             // index of current line in the list
+        int curLen;            // length of current line
+        int curLineStart;      // position of line start in whole file
+        int curLineEnd;        // position of line end in whole file
+        int maxPos;            // max position ever visited in whole file
+        int cPos;              // ordinal number of code in source
+
+        // Constructed from a list of strings, one per source line.
+        // The lines have had trailing '\n' characters removed.
+        public LineBuffer(IList<string> lineList)
+        {
+            line = lineList;
+            numLines = line.Count;
+            cPos = curLineStart = 0;
+            curLine = (numLines > 0 ? line[0] : "");
+            maxPos = curLineEnd = curLen = curLine.Length;
+            cLine = 1;
+            FileName = null;
+        }
+
+        public override int Read()
+        {
+            if (cPos < curLineEnd)
+                return curLine[cPos++ - curLineStart];
+            if (cPos++ == curLineEnd)
+                return '\n';
+            if (cLine >= numLines)
+                return EndOfFile;
+            curLine = line[cLine];
+            curLen = curLine.Length;
+            curLineStart = curLineEnd + 1;
+            curLineEnd = curLineStart + curLen;
+            if (curLineEnd > maxPos)
+                maxPos = curLineEnd;
+            cLine++;
+            return curLen > 0 ? curLine[0] : '\n';
+        }
+
+        // To speed up searches for the line containing a position
+        private int cachedPosition;
+        private int cachedIxdex;
+        private int cachedLineStart;
+
+        // Given a position pos within the entire source, the results are
+        //   ix     -- the index of the containing line
+        //   lstart -- the position of the first character on that line
+        private void findIndex(int pos, out int ix, out int lstart)
+        {
+            if (pos >= cachedPosition)
+            {
+                ix = cachedIxdex; lstart = cachedLineStart;
+            }
+            else
+            {
+                ix = lstart = 0;
+            }
+            while (ix < numLines)
+            {
+                int len = line[ix].Length + 1;
+                if (pos < lstart + len) break;
+                lstart += len;
+                ix++;
+            }
+            cachedPosition = pos;
+            cachedIxdex = ix;
+            cachedLineStart = lstart;
+        }
+
+        public override string GetString(int begin, int limit)
+        {
+            if (begin >= maxPos || limit <= begin) return "";
+            int endIx, begIx, endLineStart, begLineStart;
+            findIndex(begin, out begIx, out begLineStart);
+            int begCol = begin - begLineStart;
+            findIndex(limit, out endIx, out endLineStart);
+            int endCol = limit - endLineStart;
+            string s = line[begIx];
+            if (begIx == endIx)
+            {
+                // the usual case, substring all on one line
+                return (endCol <= s.Length) ?
+                    s.Substring(begCol, endCol - begCol)
+                    : s.Substring(begCol) + "\n";
+            }
+            // the string spans multiple lines, yuk!
+            StringBuilder sb = new StringBuilder();
+            if (begCol < s.Length)
+                sb.Append(s.Substring(begCol));
+            for (; ; )
+            {
+                sb.Append("\n");
+                s = line[++begIx];
+                if (begIx >= endIx) break;
+                sb.Append(s);
+            }
+            if (endCol <= s.Length)
+            {
+                sb.Append(s.Substring(0, endCol));
+            }
+            else
+            {
+                sb.Append(s);
+                sb.Append("\n");
+            }
+            return sb.ToString();
+        }
+
+        public override int Pos
+        {
+            get { return cPos; }
+            set
+            {
+                cPos = value;
+                findIndex(cPos, out cLine, out curLineStart);
+                // cLine should be the *next* line after curLine.
+                curLine = (cLine < numLines ? line[cLine++] : "");
+                curLineEnd = curLineStart + curLine.Length;
+            }
+        }
+
+        public override string ToString() { return "LineBuffer"; }
+    }
+
+#if (!NOFILES)
+    // ==============================================================
+    // =====     class BuildBuff : for unicode text files    ========
+    // ==============================================================
+
+    class BuildBuffer : ScanBuff
+    {
+        // Double buffer for char stream.
+        class BufferElement
+        {
+            StringBuilder bldr = new StringBuilder();
+            StringBuilder next = new StringBuilder();
+            int minIx;
+            int maxIx;
+            int brkIx;
+            bool appendToNext;
+
+            internal BufferElement() { }
+
+            internal int MaxIndex { get { return maxIx; } }
+            // internal int MinIndex { get { return minIx; } }
+
+            internal char this[int index]
+            {
+                get
+                {
+                    if (index < minIx || index >= maxIx)
+                        throw new BufferException("Index was outside data buffer");
+                    else if (index < brkIx)
+                        return bldr[index - minIx];
+                    else
+                        return next[index - brkIx];
+                }
+            }
+
+            internal void Append(char[] block, int count)
+            {
+                maxIx += count;
+                if (appendToNext)
+                    this.next.Append(block, 0, count);
+                else
+                {
+                    this.bldr.Append(block, 0, count);
+                    brkIx = maxIx;
+                    appendToNext = true;
+                }
+            }
+
+            internal string GetString(int start, int limit)
+            {
+                if (limit <= start)
+                    return "";
+                if (start >= minIx && limit <= maxIx)
+                    if (limit < brkIx) // String entirely in bldr builder
+                        return bldr.ToString(start - minIx, limit - start);
+                    else if (start >= brkIx) // String entirely in next builder
+                        return next.ToString(start - brkIx, limit - start);
+                    else // Must do a string-concatenation
+                        return
+                            bldr.ToString(start - minIx, brkIx - start) +
+                            next.ToString(0, limit - brkIx);
+                else
+                    throw new BufferException("String was outside data buffer");
+            }
+
+            internal void Mark(int limit)
+            {
+                if (limit > brkIx + 16) // Rotate blocks
+                {
+                    StringBuilder temp = bldr;
+                    bldr = next;
+                    next = temp;
+                    next.Length = 0;
+                    minIx = brkIx;
+                    brkIx = maxIx;
+                }
+            }
+        }
+
+        BufferElement data = new BufferElement();
+
+        int bPos;            // Postion index in the StringBuilder
+        BlockReader NextBlk; // Delegate that serves char-arrays;
+
+        private string EncodingName
+        {
+            get
+            {
+                StreamReader rdr = NextBlk.Target as StreamReader;
+                return (rdr == null ? "raw-bytes" : rdr.CurrentEncoding.BodyName);
+            }
+        }
+
+        public BuildBuffer(Stream stream)
+        {
+            FileStream fStrm = (stream as FileStream);
+            if (fStrm != null) FileName = fStrm.Name;
+            NextBlk = BlockReaderFactory.Raw(stream);
+        }
+
+#if (!BYTEMODE)
+        public BuildBuffer(Stream stream, int fallbackCodePage)
+        {
+            FileStream fStrm = (stream as FileStream);
+            if (fStrm != null) FileName = fStrm.Name;
+            NextBlk = BlockReaderFactory.Get(stream, fallbackCodePage);
+        }
+#endif
+
+        /// <summary>
+        /// Marks a conservative lower bound for the buffer,
+        /// allowing space to be reclaimed.  If an application 
+        /// needs to call GetString at arbitrary past locations 
+        /// in the input stream, Mark() is not called.
+        /// </summary>
+        public override void Mark() { data.Mark(bPos - 2); }
+
+        public override int Pos
+        {
+            get { return bPos; }
+            set { bPos = value; }
+        }
+
+
+        /// <summary>
+        /// Read returns the ordinal number of the next char, or 
+        /// EOF (-1) for an end of stream.  Note that the next
+        /// code point may require *two* calls of Read().
+        /// </summary>
+        /// <returns></returns>
+        public override int Read()
+        {
+            //
+            //  Characters at positions 
+            //  [data.offset, data.offset + data.bldr.Length)
+            //  are available in data.bldr.
+            //
+            if (bPos < data.MaxIndex)
+            {
+                // ch0 cannot be EOF
+                return (int)data[bPos++];
+            }
+            else // Read from underlying stream
+            {
+                // Experimental code, blocks of page size
+                char[] chrs = new char[4096];
+                int count = NextBlk(chrs, 0, 4096);
+                if (count == 0)
+                    return EndOfFile;
+                else
+                {
+                    data.Append(chrs, count);
+                    return (int)data[bPos++];
+                }
+            }
+        }
+
+        public override string GetString(int begin, int limit)
+        {
+            return data.GetString(begin, limit);
+        }
+
+        public override string ToString()
+        {
+            return "StringBuilder buffer, encoding: " + this.EncodingName;
+        }
+    }
+
+    // =============== End ScanBuff-derived classes ==================
+
+    internal delegate int BlockReader(char[] block, int index, int number);
+
+    // A delegate factory, serving up a delegate that
+    // reads a block of characters from the underlying
+    // encoded stream, via a StreamReader object.
+    //
+    internal static class BlockReaderFactory
+    {
+        public static BlockReader Raw(Stream stream)
+        {
+            return delegate(char[] block, int index, int number)
+            {
+                byte[] b = new byte[number];
+                int count = stream.Read(b, 0, number);
+                int i = 0;
+                int j = index;
+                for (; i < count; i++, j++)
+                    block[j] = (char)b[i];
+                return count;
+            };
+        }
+
+#if (!BYTEMODE)
+        public static BlockReader Get(Stream stream, int fallbackCodePage)
+        {
+            Encoding encoding;
+            int preamble = Preamble(stream);
+
+            if (preamble != 0)  // There is a valid BOM here!
+                encoding = Encoding.GetEncoding(preamble);
+            else if (fallbackCodePage == -1) // Fallback is "raw" bytes
+                return Raw(stream);
+            else if (fallbackCodePage != -2) // Anything but "guess"
+                encoding = Encoding.GetEncoding(fallbackCodePage);
+            else // This is the "guess" option
+            {
+                int guess = new Guesser(stream).GuessCodePage();
+                stream.Seek(0, SeekOrigin.Begin);
+                if (guess == -1) // ==> this is a 7-bit file
+                    encoding = Encoding.ASCII;
+                else if (guess == 65001)
+                    encoding = Encoding.UTF8;
+                else             // ==> use the machine default
+                    encoding = Encoding.Default;
+            }
+            StreamReader reader = new StreamReader(stream, encoding);
+            return reader.Read;
+        }
+
+        static int Preamble(Stream stream)
+        {
+            int b0 = stream.ReadByte();
+            int b1 = stream.ReadByte();
+
+            if (b0 == 0xfe && b1 == 0xff)
+                return 1201; // UTF16BE
+            if (b0 == 0xff && b1 == 0xfe)
+                return 1200; // UTF16LE
+
+            int b2 = stream.ReadByte();
+            if (b0 == 0xef && b1 == 0xbb && b2 == 0xbf)
+                return 65001; // UTF8
+            //
+            // There is no unicode preamble, so we
+            // return denoter for the machine default.
+            //
+            stream.Seek(0, SeekOrigin.Begin);
+            return 0;
+        }
+#endif // !BYTEMODE
+    }
+#endif // !NOFILES
+    #endregion Buffer classes
+
+    // ==============================================================
+    // ============      class CodePageHandling         =============
+    // ==============================================================
+#if (!NOFILES)
+    public static class CodePageHandling
+    {
+        public static int GetCodePage(string option)
+        {
+            string command = option.ToUpperInvariant();
+            if (command.StartsWith("CodePage:", StringComparison.OrdinalIgnoreCase))
+                command = command.Substring(9);
+            try
+            {
+                if (command.Equals("RAW"))
+                    return -1;
+                else if (command.Equals("GUESS"))
+                    return -2;
+                else if (command.Equals("DEFAULT"))
+                    return 0;
+                else if (char.IsDigit(command[0]))
+                    return int.Parse(command, CultureInfo.InvariantCulture);
+                else
+                {
+                    Encoding enc = Encoding.GetEncoding(command);
+                    return enc.CodePage;
+                }
+            }
+            catch (FormatException)
+            {
+                Console.Error.WriteLine(
+                    "Invalid format \"{0}\", using machine default", option);
+            }
+            catch (ArgumentException)
+            {
+                Console.Error.WriteLine(
+                    "Unknown code page \"{0}\", using machine default", option);
+            }
+            return 0;
+        }
+    }
+#region guesser
+#if (!BYTEMODE)
+    // ==============================================================
+    // ============          Encoding Guesser           =============
+    // ==============================================================
+
+    /// <summary>
+    /// This class provides a simple finite state automaton that
+    /// scans the file looking for (1) valid UTF-8 byte patterns,
+    /// (2) bytes >= 0x80 which are not part of a UTF-8 sequence.
+    /// The method then guesses whether it is UTF-8 or maybe some 
+    /// local machine default encoding.  This works well for the
+    /// various Latin encodings.
+    /// </summary>
+    internal class Guesser
+    {
+        ScanBuff buffer;
+
+        public int GuessCodePage() { return Scan(); }
+
+        const int maxAccept = 10;
+        const int initial = 0;
+        const int eofNum = 0;
+        const int goStart = -1;
+        const int INITIAL = 0;
+        const int EndToken = 0;
+
+        #region user code
+        /* 
+         *  Reads the bytes of a file to determine if it is 
+         *  UTF-8 or a single-byte code page file.
+         */
+        public long utfX;
+        public long uppr;
+        #endregion user code
+
+        int state;
+        int currentStart = startState[0];
+        int code;
+
+        #region ScannerTables
+        static int[] startState = new int[] { 11, 0 };
+
+        #region CharacterMap
+        static sbyte[] map = new sbyte[256] {
+/*     '\0' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*   '\x10' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*   '\x20' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      '0' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      '@' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      'P' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      '`' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      'p' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*   '\x80' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\x90' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\xA0' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\xB0' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\xC0' */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+/*   '\xD0' */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+/*   '\xE0' */ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 
+/*   '\xF0' */ 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5 };
+        #endregion
+
+        static sbyte[][] nextState = new sbyte[][] {
+            new sbyte[] {0, 0, 0, 0, 0, 0},
+            new sbyte[] {-1, -1, 10, -1, -1, -1},
+            new sbyte[] {-1, -1, -1, -1, -1, -1},
+            new sbyte[] {-1, -1, 8, -1, -1, -1},
+            new sbyte[] {-1, -1, 5, -1, -1, -1},
+            new sbyte[] {-1, -1, 6, -1, -1, -1},
+            new sbyte[] {-1, -1, 7, -1, -1, -1},
+            null,
+            new sbyte[] {-1, -1, 9, -1, -1, -1},
+            null,
+            null,
+            new sbyte[] {-1, 1, 2, 3, 4, 2}
+        };
+
+
+        [SuppressMessage("Microsoft.Performance", "CA1810:InitializeReferenceTypeStaticFieldsInline")]
+        // Reason for suppression: cannot have self-reference in array initializer.
+        static Guesser()
+        {
+            nextState[7] = nextState[2];
+            nextState[9] = nextState[2];
+            nextState[10] = nextState[2];
+        }
+
+        int NextState()
+        {
+            if (code == ScanBuff.EndOfFile)
+                return eofNum;
+            else
+                return nextState[state][map[code]];
+        }
+        #endregion
+
+        public Guesser(System.IO.Stream file) { SetSource(file); }
+
+        public void SetSource(System.IO.Stream source)
+        {
+            this.buffer = new BuildBuffer(source);
+            code = buffer.Read();
+        }
+
+        int Scan()
+        {
+            for (; ; )
+            {
+                int next;
+                state = currentStart;
+                while ((next = NextState()) == goStart)
+                    code = buffer.Read();
+
+                state = next;
+                code = buffer.Read();
+
+                while ((next = NextState()) > eofNum)
+                {
+                    state = next;
+                    code = buffer.Read();
+                }
+                if (state <= maxAccept)
+                {
+                    #region ActionSwitch
+#pragma warning disable 162
+                    switch (state)
+                    {
+                        case eofNum:
+                            switch (currentStart)
+                            {
+                                case 11:
+                                    if (utfX == 0 && uppr == 0) return -1; /* raw ascii */
+                                    else if (uppr * 10 > utfX) return 0;   /* default code page */
+                                    else return 65001;                     /* UTF-8 encoding */
+                                    break;
+                            }
+                            return EndToken;
+                        case 1: // Recognized '{Upper128}',	Shortest string "\xC0"
+                        case 2: // Recognized '{Upper128}',	Shortest string "\x80"
+                        case 3: // Recognized '{Upper128}',	Shortest string "\xE0"
+                        case 4: // Recognized '{Upper128}',	Shortest string "\xF0"
+                            uppr++;
+                            break;
+                        case 5: // Recognized '{Utf8pfx4}{Utf8cont}',	Shortest string "\xF0\x80"
+                            uppr += 2;
+                            break;
+                        case 6: // Recognized '{Utf8pfx4}{Utf8cont}{2}',	Shortest string "\xF0\x80\x80"
+                            uppr += 3;
+                            break;
+                        case 7: // Recognized '{Utf8pfx4}{Utf8cont}{3}',	Shortest string "\xF0\x80\x80\x80"
+                            utfX += 3;
+                            break;
+                        case 8: // Recognized '{Utf8pfx3}{Utf8cont}',	Shortest string "\xE0\x80"
+                            uppr += 2;
+                            break;
+                        case 9: // Recognized '{Utf8pfx3}{Utf8cont}{2}',	Shortest string "\xE0\x80\x80"
+                            utfX += 2;
+                            break;
+                        case 10: // Recognized '{Utf8pfx2}{Utf8cont}',	Shortest string "\xC0\x80"
+                            utfX++;
+                            break;
+                        default:
+                            break;
+                    }
+#pragma warning restore 162
+                    #endregion
+                }
+            }
+        }
+    } // end class Guesser
+    
+#endif // !BYTEMODE
+#endregion
+#endif // !NOFILES
+
+// End of code copied from embedded resource
+}

src/DataStreamSuite/Bts.ColumnExpressions/ShiftReduceParserCode.cs

@@ -0,0 +1,884 @@
+// ==============================================================
+// <auto-generated>
+// This code automatically produced from an embedded resource.
+// Do not edit this file, or it will become incompatible with 
+// the specification from which it was generated.
+// </auto-generated>
+// ==============================================================
+
+// Gardens Point Parser Generator
+// Copyright (c) Wayne Kelly, QUT 2005-2010
+// (see accompanying GPPGcopyright.rtf)
+
+using System;
+using System.Text;
+using System.Globalization;
+using System.Collections.Generic;
+using System.Runtime.Serialization;
+using System.Diagnostics.CodeAnalysis;
+
+namespace QUT.Gppg {
+    /// <summary>
+    /// Abstract class for GPPG shift-reduce parsers.
+    /// Parsers generated by GPPG derive from this base
+    /// class, overriding the abstract Initialize() and
+    /// DoAction() methods.
+    /// </summary>
+    /// <typeparam name="TValue">Semantic value type</typeparam>
+    /// <typeparam name="TSpan">Location type</typeparam>
+#if EXPORT_GPPG
+    public abstract class ShiftReduceParser<TValue, TSpan>
+#else
+    internal abstract class ShiftReduceParser<TValue, TSpan>
+#endif
+ where TSpan : IMerge<TSpan>, new() {
+        private AbstractScanner<TValue, TSpan> scanner;
+        /// <summary>
+        /// The abstract scanner for this parser.
+        /// </summary>
+        protected AbstractScanner<TValue, TSpan> Scanner {
+            get { return scanner; }
+            set { scanner = value; }
+        }
+
+        /// <summary>
+        /// Constructor for base class
+        /// </summary>
+        /// <param name="scanner">Scanner instance for this parser</param>
+        protected ShiftReduceParser( AbstractScanner<TValue, TSpan> scanner ) {
+            this.scanner = scanner;
+        }
+
+        // ==============================================================
+        //                    TECHNICAL EXPLANATION.
+        //   Why the next two fields are not exposed via properties.
+        // ==============================================================
+        // These fields are of the generic parameter types, and are
+        // frequently instantiated as struct types in derived classes.
+        // Semantic actions are defined in the derived classes and refer
+        // to instance fields of these structs.  In such cases the code
+        // "get_CurrentSemanticValue().myField = blah;" will fail since
+        // the getter pushes the value of the field, not the reference.
+        // So, in the presence of properties, gppg would need to encode
+        // such field accesses as ... 
+        //  "tmp = get_CurrentSemanticValue(); // Fetch value
+        //   tmp.myField = blah;               // update
+        //   set_CurrentSemanticValue(tmp); "  // Write update back.
+        // There is no issue if TValue is restricted to be a ref type.
+        // The same explanation applies to scanner.yylval.
+        // ==============================================================
+        /// <summary>
+        /// The current value of the "$$" symbolic variable in the parser
+        /// </summary>
+        [SuppressMessage( "Microsoft.Design", "CA1051:DoNotDeclareVisibleInstanceFields" )]
+        protected TValue CurrentSemanticValue;
+
+        /// <summary>
+        /// The current value of the "@$" symbolic variable in the parser
+        /// </summary>
+        [SuppressMessage( "Microsoft.Design", "CA1051:DoNotDeclareVisibleInstanceFields" )]
+        protected TSpan CurrentLocationSpan;
+        protected int NextToken;
+
+        private TSpan LastSpan;
+        private State FsaState;
+        private bool recovering;
+        private int tokensSinceLastError;
+
+        private PushdownPrefixState<State> StateStack = new PushdownPrefixState<State>();
+        private PushdownPrefixState<TValue> valueStack = new PushdownPrefixState<TValue>();
+        private PushdownPrefixState<TSpan> locationStack = new PushdownPrefixState<TSpan>();
+
+        /// <summary>
+        /// The stack of semantic value (YYSTYPE) values.
+        /// </summary>
+        protected PushdownPrefixState<TValue> ValueStack { get { return valueStack; } }
+
+        /// <summary>
+        /// The stack of location value (YYLTYPE) varlues.
+        /// </summary>
+        protected PushdownPrefixState<TSpan> LocationStack { get { return locationStack; } }
+
+        private int errorToken;
+        private int endOfFileToken;
+        private string[] nonTerminals;
+        private State[] states;
+        private Rule[] rules;
+
+        /// <summary>
+        /// Initialization method to allow derived classes
+        /// to insert the rule list into this base class.
+        /// </summary>
+        /// <param name="rules">The array of Rule objects</param>
+        protected void InitRules( Rule[] rules ) { this.rules = rules; }
+
+        /// <summary>
+        /// Initialization method to allow derived classes to
+        /// insert the states table into this base class.
+        /// </summary>
+        /// <param name="states">The pre-initialized states table</param>
+        protected void InitStates( State[] states ) { this.states = states; }
+
+        /// <summary>
+        /// OBSOLETE FOR VERSION 1.4.0
+        /// </summary>
+        /// <param name="size"></param>
+        protected void InitStateTable( int size ) { states = new State[size]; }
+
+        /// <summary>
+        /// Initialization method to allow derived classes
+        /// to insert the special value for the error and EOF tokens.
+        /// </summary>
+        /// <param name="err">The error state ordinal</param>
+        /// <param name="end">The EOF stat ordinal</param>
+        protected void InitSpecialTokens( int err, int end ) {
+            errorToken = err;
+            endOfFileToken = end;
+        }
+
+        /// <summary>
+        /// Initialization method to allow derived classes to
+        /// insert the non-terminal symbol names into this base class.
+        /// </summary>
+        /// <param name="names">Non-terminal symbol names</param>
+        protected void InitNonTerminals( string[] names ) { nonTerminals = names; }
+
+        #region YYAbort, YYAccept etcetera.
+        [Serializable]
+        [SuppressMessage( "Microsoft.Design", "CA1064:ExceptionsShouldBePublic" )]
+        // Reason for FxCop message suppression -
+        // This exception cannot escape from the local context
+        private class AcceptException : Exception {
+            internal AcceptException() { }
+            protected AcceptException( SerializationInfo i, StreamingContext c ) : base( i, c ) { }
+        }
+        [Serializable]
+        [SuppressMessage( "Microsoft.Design", "CA1064:ExceptionsShouldBePublic" )]
+        // Reason for FxCop message suppression -
+        // This exception cannot escape from the local context
+        private class AbortException : Exception {
+            internal AbortException() { }
+            protected AbortException( SerializationInfo i, StreamingContext c ) : base( i, c ) { }
+        }
+        [Serializable]
+        [SuppressMessage( "Microsoft.Design", "CA1064:ExceptionsShouldBePublic" )]
+        // Reason for FxCop message suppression -
+        // This exception cannot escape from the local context
+        private class ErrorException : Exception {
+            internal ErrorException() { }
+            protected ErrorException( SerializationInfo i, StreamingContext c ) : base( i, c ) { }
+        }
+
+        // The following methods are only called from within
+        // a semantic action. The thrown exceptions can never
+        // propagate outside the ShiftReduceParser class in 
+        // which they are nested.
+
+        /// <summary>
+        /// Force parser to terminate, returning "true"
+        /// </summary>
+        protected static void YYAccept() { throw new AcceptException(); }
+
+        /// <summary>
+        /// Force parser to terminate, returning "false"
+        /// </summary>
+        protected static void YYAbort() { throw new AbortException(); }
+
+        /// <summary>
+        /// Force parser to terminate, returning
+        /// "false" if error recovery fails.
+        /// </summary>
+        protected static void YYError() { throw new ErrorException(); }
+
+        /// <summary>
+        /// Check if parser in error recovery state.
+        /// </summary>
+        protected bool YYRecovering { get { return recovering; } }
+        #endregion
+
+        /// <summary>
+        /// Abstract base method. ShiftReduceParser calls this
+        /// to initialize the base class data structures.  Concrete
+        /// parser classes must override this method.
+        /// </summary>
+        protected abstract void Initialize();
+
+        /// <summary>
+        /// Main entry point of the Shift-Reduce Parser.
+        /// </summary>
+        /// <returns>True if parse succeeds, else false for
+        /// unrecoverable errors</returns>
+        public bool Parse() {
+            Initialize();	// allow derived classes to instantiate rules, states and nonTerminals
+
+            NextToken = 0;
+            FsaState = states[0];
+
+            StateStack.Push( FsaState );
+            valueStack.Push( CurrentSemanticValue );
+            LocationStack.Push( CurrentLocationSpan );
+
+            while (true) {
+#if TRACE_ACTIONS
+                Console.Error.WriteLine("Entering state {0} ", FsaState.number);
+                DisplayStack();
+#endif
+                int action = FsaState.defaultAction;
+
+                if (FsaState.ParserTable != null) {
+                    if (NextToken == 0) {
+                        // We save the last token span, so that the location span
+                        // of production right hand sides that begin or end with a
+                        // nullable production will be correct.
+                        LastSpan = scanner.yylloc;
+                        NextToken = scanner.yylex();
+#if TRACE_ACTIONS
+                       Console.Error.WriteLine( "Reading: Next token is {0}", TerminalToString( NextToken ) );
+#endif
+                    }
+#if TRACE_ACTIONS
+                    else 
+                        Console.Error.WriteLine( "Next token is still {0}", TerminalToString( NextToken ) );
+#endif
+                    if (FsaState.ParserTable.ContainsKey( NextToken ))
+                        action = FsaState.ParserTable[NextToken];
+                }
+
+                if (action > 0)         // shift
+                {
+                    Shift( action );
+                }
+                else if (action < 0)   // reduce
+                {
+                    try {
+                        Reduce( -action );
+                        if (action == -1)	// accept
+                            return true;
+                    }
+                    catch (AbortException) {
+                            return false;
+                    }
+                    catch (AcceptException) {
+                        return true;
+                    }
+                    catch (ErrorException) {
+                        if (!ErrorRecovery())
+                            return false;
+                        else
+                            throw;  // Rethrow x, preserving information.
+                    }
+                }
+                else if (action == 0 && !ErrorRecovery()) // error
+                    return false;
+            }
+        }
+
+        private void Shift( int stateIndex ) {
+#if TRACE_ACTIONS
+				Console.Error.Write("Shifting token {0}, ", TerminalToString(NextToken));
+#endif
+            FsaState = states[stateIndex];
+
+            valueStack.Push( scanner.yylval );
+            StateStack.Push( FsaState );
+            LocationStack.Push( scanner.yylloc );
+
+            if (recovering) {
+                if (NextToken != errorToken)
+                    tokensSinceLastError++;
+
+                if (tokensSinceLastError > 5)
+                    recovering = false;
+            }
+
+            if (NextToken != endOfFileToken)
+                NextToken = 0;
+        }
+
+        private void Reduce( int ruleNumber ) {
+#if TRACE_ACTIONS
+				DisplayRule(ruleNumber);
+#endif
+            Rule rule = rules[ruleNumber];
+            int rhLen = rule.RightHandSide.Length;
+            //
+            //  Default actions for unit productions.
+            //
+            if (rhLen == 1) {
+                CurrentSemanticValue = valueStack.TopElement();   // Default action: $$ = $1;
+                CurrentLocationSpan = LocationStack.TopElement(); // Default action "@$ = @1;
+            }
+            else if (rhLen == 0) {
+                // Create a new blank value.
+                // Explicit semantic action may mutate this value
+                CurrentSemanticValue = default( TValue );
+                // The location span for an empty production will start with the
+                // beginning of the next lexeme, and end with the finish of the
+                // previous lexeme.  This gives the correct behaviour when this
+                // nonsense value is used in later Merge operations.
+                CurrentLocationSpan = (scanner.yylloc != null && LastSpan != null ?
+                    scanner.yylloc.Merge( LastSpan ) :
+                    default( TSpan ));
+            }
+            else {
+                // Default action: $$ = $1;
+                CurrentSemanticValue = valueStack[LocationStack.Depth - rhLen];
+                //  Default action "@$ = @1.Merge(@N)" for location info.
+                TSpan at1 = LocationStack[LocationStack.Depth - rhLen];
+                TSpan atN = LocationStack[LocationStack.Depth - 1];
+                CurrentLocationSpan =
+                    ((at1 != null && atN != null) ? at1.Merge( atN ) : default( TSpan ));
+            }
+
+            DoAction( ruleNumber );
+
+            for (int i = 0; i < rule.RightHandSide.Length; i++) {
+                StateStack.Pop();
+                valueStack.Pop();
+                LocationStack.Pop();
+            }
+            FsaState = StateStack.TopElement();
+
+            if (FsaState.Goto.ContainsKey( rule.LeftHandSide ))
+                FsaState = states[FsaState.Goto[rule.LeftHandSide]];
+
+            StateStack.Push( FsaState );
+            valueStack.Push( CurrentSemanticValue );
+            LocationStack.Push( CurrentLocationSpan );
+        }
+
+        /// <summary>
+        /// Execute the selected action from array.
+        /// Must be overriden in derived classes.
+        /// </summary>
+        /// <param name="actionNumber">Index of the action to perform</param>
+        protected abstract void DoAction( int actionNumber );
+
+        private bool ErrorRecovery() {
+            bool discard;
+
+            if (!recovering) // if not recovering from previous error
+                ReportError();
+
+            if (!FindErrorRecoveryState())
+                return false;
+            //
+            //  The interim fix for the "looping in error recovery"
+            //  artifact involved moving the setting of the recovering 
+            //  bool until after invalid tokens have been discarded.
+            //
+            ShiftErrorToken();
+            discard = DiscardInvalidTokens();
+            recovering = true;
+            tokensSinceLastError = 0;
+            return discard;
+        }
+
+        private void ReportError() {
+            StringBuilder errorMsg = new StringBuilder();
+            errorMsg.AppendFormat( "Syntax error, unexpected {0}", TerminalToString( NextToken ) );
+
+            if (FsaState.ParserTable.Count < 7) {
+                bool first = true;
+                foreach (int terminal in FsaState.ParserTable.Keys) {
+                    if (first)
+                        errorMsg.Append( ", expecting " );
+                    else
+                        errorMsg.Append( ", or " );
+
+                    errorMsg.Append( TerminalToString( terminal ) );
+                    first = false;
+                }
+            }
+            scanner.yyerror( errorMsg.ToString() );
+        }
+
+        private void ShiftErrorToken() {
+            int old_next = NextToken;
+            NextToken = errorToken;
+
+            Shift( FsaState.ParserTable[NextToken] );
+
+#if TRACE_ACTIONS
+				Console.Error.WriteLine("Entering state {0} ", FsaState.number);
+#endif
+            NextToken = old_next;
+        }
+
+        private bool FindErrorRecoveryState() {
+            while (true)    // pop states until one found that accepts error token
+            {
+                if (FsaState.ParserTable != null &&
+                    FsaState.ParserTable.ContainsKey( errorToken ) &&
+                    FsaState.ParserTable[errorToken] > 0) // shift
+                    return true;
+
+#if TRACE_ACTIONS
+					Console.Error.WriteLine("Error: popping state {0}", StateStack.TopElement().number);
+#endif
+                StateStack.Pop();
+                valueStack.Pop();
+                LocationStack.Pop();
+
+#if TRACE_ACTIONS
+			    DisplayStack();
+#endif
+                if (StateStack.IsEmpty()) {
+#if TRACE_ACTIONS
+                        Console.Error.WriteLine("Aborting: didn't find a state that accepts error token");
+#endif
+                    return false;
+                }
+                else
+                    FsaState = StateStack.TopElement();
+            }
+        }
+
+        private bool DiscardInvalidTokens() {
+
+            int action = FsaState.defaultAction;
+
+            if (FsaState.ParserTable != null) {
+                // Discard tokens until find one that works ...
+                while (true) {
+                    if (NextToken == 0) {
+#if TRACE_ACTIONS
+                            Console.Error.Write("Reading a token: ");
+#endif
+                        NextToken = scanner.yylex();
+                    }
+#if TRACE_ACTIONS
+                        Console.Error.WriteLine("Next token is {0}", TerminalToString(NextToken));
+#endif
+                    if (NextToken == endOfFileToken)
+                        return false;
+
+                    if (FsaState.ParserTable.ContainsKey( NextToken ))
+                        action = FsaState.ParserTable[NextToken];
+
+                    if (action != 0)
+                        return true;
+                    else {
+#if TRACE_ACTIONS
+                            Console.Error.WriteLine("Error: Discarding {0}", TerminalToString(NextToken));
+#endif
+                        NextToken = 0;
+                    }
+                }
+            }
+            else if (recovering && tokensSinceLastError == 0) {
+                // 
+                //  Boolean recovering is not set until after the first
+                //  error token has been shifted.  Thus if we get back 
+                //  here with recovering set and no tokens read we are
+                //  looping on the same error recovery action.  This 
+                //  happens if current_state.ParserTable is null because
+                //  the state has an LR(0) reduction, but not all
+                //  lookahead tokens are valid.  This only occurs for
+                //  error productions that *end* on "error".
+                //
+                //  This action discards tokens one at a time until
+                //  the looping stops.  Another attack would be to always
+                //  use the LALR(1) table if a production ends on "error"
+                //
+#if TRACE_ACTIONS
+                    Console.Error.WriteLine("Error: panic discard of {0}", TerminalToString(NextToken));
+#endif
+                if (NextToken == endOfFileToken)
+                    return false;
+                NextToken = 0;
+                return true;
+            }
+            else
+                return true;
+        }
+
+        /// <summary>
+        /// Traditional YACC method.  Discards the next input token.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yyclearin" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yyclearin" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        protected void yyclearin() { NextToken = 0; }
+
+        /// <summary>
+        /// Tradional YACC method. Clear the "recovering" flag.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yyerrok" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yyerrok" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        protected void yyerrok() { recovering = false; }
+
+        /// <summary>
+        /// OBSOLETE FOR VERSION 1.4.0
+        /// Method used by derived types to insert new
+        /// state instances in the "states" array.
+        /// </summary>
+        /// <param name="stateNumber">index of the state</param>
+        /// <param name="state">data for the state</param>
+        protected void AddState( int stateNumber, State state ) {
+            states[stateNumber] = state;
+            state.number = stateNumber;
+        }
+
+        private void DisplayStack() {
+            Console.Error.Write( "State stack is now:" );
+            for (int i = 0; i < StateStack.Depth; i++)
+                Console.Error.Write( " {0}", StateStack[i].number );
+            Console.Error.WriteLine();
+        }
+
+        private void DisplayRule( int ruleNumber ) {
+            Console.Error.Write( "Reducing stack by rule {0}, ", ruleNumber );
+            DisplayProduction( rules[ruleNumber] );
+        }
+
+        private void DisplayProduction( Rule rule ) {
+            if (rule.RightHandSide.Length == 0)
+                Console.Error.Write( "/* empty */ " );
+            else
+                foreach (int symbol in rule.RightHandSide)
+                    Console.Error.Write( "{0} ", SymbolToString( symbol ) );
+
+            Console.Error.WriteLine( "-> {0}", SymbolToString( rule.LeftHandSide ) );
+        }
+
+        /// <summary>
+        /// Abstract state class naming terminal symbols.
+        /// This is overridden by derived classes with the
+        /// name (or alias) to be used in error messages.
+        /// </summary>
+        /// <param name="terminal">The terminal ordinal</param>
+        /// <returns></returns>
+        protected abstract string TerminalToString( int terminal );
+
+        private string SymbolToString( int symbol ) {
+            if (symbol < 0)
+                return nonTerminals[-symbol - 1];
+            else
+                return TerminalToString( symbol );
+        }
+
+        /// <summary>
+        /// Return text representation of argument character
+        /// </summary>
+        /// <param name="input">The character to convert</param>
+        /// <returns>String representation of the character</returns>
+        protected static string CharToString( char input ) {
+            switch (input) {
+                case '\a': return @"'\a'";
+                case '\b': return @"'\b'";
+                case '\f': return @"'\f'";
+                case '\n': return @"'\n'";
+                case '\r': return @"'\r'";
+                case '\t': return @"'\t'";
+                case '\v': return @"'\v'";
+                case '\0': return @"'\0'";
+                default: return string.Format( CultureInfo.InvariantCulture, "'{0}'", input );
+            }
+        }
+    }
+
+    /// <summary>
+    /// Classes implementing this interface must supply a
+    /// method that merges two location objects to return
+    /// a new object of the same type.
+    /// GPPG-generated parsers have the default location
+    /// action equivalent to "@$ = @1.Merge(@N);" where N
+    /// is the right-hand-side length of the production.
+    /// </summary>
+    /// <typeparam name="TSpan">The Location type</typeparam>
+#if EXPORT_GPPG
+    public interface IMerge<TSpan>
+#else
+    internal interface IMerge<TSpan>
+#endif
+ {
+        /// <summary>
+        /// Interface method that creates a location object from
+        /// the current and last object.  Typically used to create
+        /// a location object extending from the start of the @1
+        /// object to the end of the @N object.
+        /// </summary>
+        /// <param name="last">The lexically last object to merge</param>
+        /// <returns>The merged location object</returns>
+        TSpan Merge( TSpan last );
+    }
+
+    /// <summary>
+    /// This is the default class that carries location
+    /// information from the scanner to the parser.
+    /// If you don't declare "%YYLTYPE Foo" the parser
+    /// will expect to deal with this type.
+    /// </summary>
+#if EXPORT_GPPG
+    public class LexLocation : IMerge<LexLocation>
+#else
+    [SuppressMessage( "Microsoft.Performance", "CA1812:AvoidUninstantiatedInternalClasses" )]
+    internal class LexLocation : IMerge<LexLocation>
+#endif
+ {
+        private int startLine;   // start line
+        private int startColumn; // start column
+        private int endLine;     // end line
+        private int endColumn;   // end column
+
+        /// <summary>
+        /// The line at which the text span starts.
+        /// </summary>
+        public int StartLine { get { return startLine; } }
+
+        /// <summary>
+        /// The column at which the text span starts.
+        /// </summary>
+        public int StartColumn { get { return startColumn; } }
+
+        /// <summary>
+        /// The line on which the text span ends.
+        /// </summary>
+        public int EndLine { get { return endLine; } }
+
+        /// <summary>
+        /// The column of the first character
+        /// beyond the end of the text span.
+        /// </summary>
+        public int EndColumn { get { return endColumn; } }
+
+        /// <summary>
+        /// Default no-arg constructor.
+        /// </summary>
+        public LexLocation() { }
+
+        /// <summary>
+        /// Constructor for text-span with given start and end.
+        /// </summary>
+        /// <param name="sl">start line</param>
+        /// <param name="sc">start column</param>
+        /// <param name="el">end line </param>
+        /// <param name="ec">end column</param>
+        public LexLocation( int sl, int sc, int el, int ec ) { startLine = sl; startColumn = sc; endLine = el; endColumn = ec; }
+
+        /// <summary>
+        /// Create a text location which spans from the 
+        /// start of "this" to the end of the argument "last"
+        /// </summary>
+        /// <param name="last">The last location in the result span</param>
+        /// <returns>The merged span</returns>
+        public LexLocation Merge( LexLocation last ) { return new LexLocation( this.startLine, this.startColumn, last.endLine, last.endColumn ); }
+    }
+
+    /// <summary>
+    /// Abstract scanner class that GPPG expects its scanners to 
+    /// extend.
+    /// </summary>
+    /// <typeparam name="TValue">Semantic value type YYSTYPE</typeparam>
+    /// <typeparam name="TSpan">Source location type YYLTYPE</typeparam>
+#if EXPORT_GPPG
+    public abstract class AbstractScanner<TValue, TSpan>
+#else
+    internal abstract class AbstractScanner<TValue, TSpan>
+#endif
+ where TSpan : IMerge<TSpan> {
+        /// <summary>
+        /// Lexical value optionally set by the scanner. The value
+        /// is of the %YYSTYPE type declared in the parser spec.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Design", "CA1051:DoNotDeclareVisibleInstanceFields" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yylval" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yylval" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        // A field must be declared for this value of parametric type,
+        // since it may be instantiated by a value struct.  If it were 
+        // implemented as a property, machine generated code in derived
+        // types would not be able to select on the returned value.
+#pragma warning disable 649
+        public TValue yylval;                     // Lexical value: set by scanner
+#pragma warning restore 649
+
+        /// <summary>
+        /// Current scanner location property. The value is of the
+        /// type declared by %YYLTYPE in the parser specification.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yylloc" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yylloc" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        public virtual TSpan yylloc {
+            get { return default( TSpan ); }       // Empty implementation allowing
+            set { /* skip */ }                   // yylloc to be ignored entirely.
+        }
+
+        /// <summary>
+        /// Main call point for LEX-like scanners.  Returns an int
+        /// corresponding to the token recognized by the scanner.
+        /// </summary>
+        /// <returns>An int corresponding to the token</returns>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yylex" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yylex" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        public abstract int yylex();
+
+        /// <summary>
+        /// Traditional error reporting provided by LEX-like scanners
+        /// to their YACC-like clients.
+        /// </summary>
+        /// <param name="format">Message format string</param>
+        /// <param name="args">Optional array of args</param>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yyerror" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yyerror" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        public virtual void yyerror( string format, params object[] args ) { }
+    }
+
+    /// <summary>
+    /// Encapsulated state for the parser.
+    /// Opaque to users, visible to the tool-generated code.
+    /// </summary>
+#if EXPORT_GPPG
+    public class State
+    {
+        /// <summary>
+        /// The number of states in the automaton.
+        /// </summary>
+        public int number;
+#else
+    internal class State {
+        /// <summary>
+        /// The index of this state in the states array.
+        /// </summary>
+        internal int number;
+#endif
+        internal Dictionary<int, int> ParserTable;   // Terminal -> ParseAction
+        internal Dictionary<int, int> Goto;          // NonTerminal -> State;
+        internal int defaultAction; // = 0;		     // ParseAction
+
+        /// <summary>
+        /// State transition data for this state. Pairs of elements of the 
+        /// goto array associate symbol ordinals with next state indices.
+        /// The actions array is passed to another constructor. 
+        /// </summary>
+        /// <param name="actions">The action list</param>c
+        /// <param name="goToList">Next state data</param>
+        public State( int[] actions, int[] goToList )
+            : this( actions ) {
+            Goto = new Dictionary<int, int>();
+            for (int i = 0; i < goToList.Length; i += 2)
+                Goto.Add( goToList[i], goToList[i + 1] );
+        }
+
+        /// <summary>
+        /// Action data for this state. Pairs of elements of the 
+        /// action array associate action ordinals with each of
+        /// those symbols that have actions in the current state.
+        /// </summary>
+        /// <param name="actions">The action array</param>
+        public State( int[] actions ) {
+            ParserTable = new Dictionary<int, int>();
+            for (int i = 0; i < actions.Length; i += 2)
+                ParserTable.Add( actions[i], actions[i + 1] );
+        }
+
+        /// <summary>
+        /// Set the default action for this state.
+        /// </summary>
+        /// <param name="defaultAction">Ordinal of the default action</param>
+        public State( int defaultAction ) {
+            this.defaultAction = defaultAction;
+        }
+
+        /// <summary>
+        /// Set the default action and the state transition table.
+        /// </summary>
+        /// <param name="defaultAction">The default action</param>
+        /// <param name="goToList">Transitions from this state</param>
+        public State( int defaultAction, int[] goToList )
+            : this( defaultAction ) {
+            Goto = new Dictionary<int, int>();
+            for (int i = 0; i < goToList.Length; i += 2)
+                Goto.Add( goToList[i], goToList[i + 1] );
+        }
+    }
+
+    /// <summary>
+    /// Rule representation at runtime.
+    /// </summary>
+#if EXPORT_GPPG
+    public class Rule
+#else
+    internal class Rule
+#endif
+ {
+        internal int LeftHandSide; // symbol
+        internal int[] RightHandSide; // symbols
+
+        /// <summary>
+        /// Rule constructor.  This holds the ordinal of
+        /// the left hand side symbol, and the list of
+        /// right hand side symbols, in lexical order.
+        /// </summary>
+        /// <param name="left">The LHS non-terminal</param>
+        /// <param name="right">The RHS symbols, in lexical order</param>
+        public Rule( int left, int[] right ) {
+            this.LeftHandSide = left;
+            this.RightHandSide = right;
+        }
+    }
+
+    /// <summary>
+    /// Stack utility for the shift-reduce parser.
+    /// GPPG parsers have three instances:
+    /// (1) The parser state stack, T = QUT.Gppg.State,
+    /// (2) The semantic value stack, T = TValue,
+    /// (3) The location stack, T = TSpan.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+#if EXPORT_GPPG
+    public class PushdownPrefixState<T>
+#else
+    internal class PushdownPrefixState<T>
+#endif
+ {
+        //  Note that we cannot use the BCL Stack<T> class
+        //  here as derived types need to index into stacks.
+        //
+        private T[] array = new T[8];
+        private int tos = 0;
+
+        /// <summary>
+        /// Indexer for values of the stack below the top.
+        /// </summary>
+        /// <param name="index">index of the element, starting from the bottom</param>
+        /// <returns>the selected element</returns>
+        public T this[int index] { get { return array[index]; } }
+
+        /// <summary>
+        /// The current depth of the stack.
+        /// </summary>
+        public int Depth { get { return tos; } }
+
+        internal void Push( T value ) {
+            if (tos >= array.Length) {
+                T[] newarray = new T[array.Length * 2];
+                System.Array.Copy( array, newarray, tos );
+                array = newarray;
+            }
+            array[tos++] = value;
+        }
+
+        internal T Pop() {
+            T rslt = array[--tos];
+            array[tos] = default( T );
+            return rslt;
+        }
+
+        internal T TopElement() { return array[tos - 1]; }
+
+        internal bool IsEmpty() { return tos == 0; }
+    }
+}
+

src/DataStreamSuite/Bts.ColumnExpressions/Usings.cs

@@ -0,0 +1,4 @@
+global using System;
+global using System.Linq;
+global using System.Collections.Generic;
+global using System.Collections.Immutable;

src/DataStreamSuite/Bts.ColumnSortExpressions/Bts.ColumnSortExpressions.csproj

@@ -0,0 +1,24 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="YaccLexTools" Version="1.2.2" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\DataStreamCore\DataStreamCore.csproj" />
+    <ProjectReference Include="..\ExpressionCore\ExpressionCore.csproj" />
+    <ProjectReference Include="..\..\client\spark_core\spark_core.csproj" />
+  </ItemGroup>
+
+  <ItemGroup Label="ColumnSortExpression">
+    <Scanner Include="ColumnSortExpressionTokens.lex" />
+    <Parser Include="ColumnSortExpressionGrammar.y" />
+  </ItemGroup>
+
+</Project>

src/DataStreamSuite/Bts.ColumnSortExpressions/ColumnSortExpression.cs

@@ -0,0 +1,11 @@
+namespace Bts.ColumnSortExpressions;
+
+public class ColumnSortExpression {
+   public ColumnSortExpression(string name, bool isAscending = true) {
+      Name = name;
+      IsAscending = isAscending;
+   }
+
+   public string Name { get; }
+   public bool IsAscending { get; }
+}

src/DataStreamSuite/Bts.ColumnSortExpressions/ColumnSortExpressionGrammar.y

@@ -0,0 +1,29 @@
+%namespace Bts.ColumnSortExpressions
+%partial
+%visibility internal
+%tokentype ColumnSortExpressionToken
+%parsertype ColumnSortExpressionParser
+
+%union {
+   public string Identifier;
+   public ColumnSortExpression Column;
+   public ImmutableList<ColumnSortExpression> Columns;
+}
+
+%token ASCENDING, DESCENDING, IDENTIFIER
+
+%type <Column> Column
+%type <Columns> Columns
+
+%%
+
+Columns :
+   Column { $$ = ImmutableList.CreateRange(new[] { $1 }); }
+   | Columns Column { $$ = $1.Add($2); }
+   ;
+
+Column :
+   IDENTIFIER { $$ = new($1.Identifier, true); }
+   | ASCENDING IDENTIFIER { $$ = new($2.Identifier, true); }
+   | DESCENDING IDENTIFIER { $$ = new($2.Identifier, false); }
+   ;

src/DataStreamSuite/Bts.ColumnSortExpressions/ColumnSortExpressionInterpreter.cs

@@ -0,0 +1,18 @@
+namespace Bts.ColumnSortExpressions;
+
+using System.IO;
+using System.Text;
+
+public class ColumnSortExpressionInterpreter {
+   public static IList<ColumnSortExpression> Evaluate(Stream stream) {
+      var parser = new ColumnSortExpressionParser();
+      var res = parser.Parse(stream);
+      return res?.Columns ?? ImmutableList<ColumnSortExpression>.Empty.Add(
+         res?.Column ?? throw new Exception("Failed to parse column(s) expression"));
+   }
+
+   public static IList<ColumnSortExpression> Evaluate(string str) {
+      using var ms = new MemoryStream(Encoding.Default.GetBytes(str));
+      return Evaluate(ms);
+   }
+}

src/DataStreamSuite/Bts.ColumnSortExpressions/ColumnSortExpressionParser.cs

@@ -0,0 +1,18 @@
+namespace Bts.ColumnSortExpressions;
+
+using System.Text;
+
+partial class ColumnSortExpressionParser {
+   public ColumnSortExpressionParser() : base(null) { }
+
+   public ValueType? Parse(string s) {
+      using var ms = new MemoryStream(Encoding.Default.GetBytes(s));
+      return Parse(ms);
+   }
+
+   public ValueType? Parse(Stream stream) {
+      Scanner = new ColumnSortExpressionScanner(stream);
+      Parse();
+      return CurrentSemanticValue;
+   }
+}

src/DataStreamSuite/Bts.ColumnSortExpressions/ColumnSortExpressionScanner.cs

@@ -0,0 +1,9 @@
+namespace Bts.ColumnSortExpressions;
+
+partial class ColumnSortExpressionScanner {
+   public override void yyerror(string format, params object[] args) {
+      base.yyerror(format, args);
+      Console.WriteLine(format, args);
+      Console.WriteLine();
+   }
+}

src/DataStreamSuite/Bts.ColumnSortExpressions/ColumnSortExpressionTokens.lex

@@ -0,0 +1,30 @@
+%namespace Bts.ColumnSortExpressions
+%scannertype ColumnSortExpressionScanner
+%visibility internal
+%tokentype ColumnSortExpressionToken
+
+%option stack, minimize, parser, verbose, persistbuffer, noembedbuffers 
+
+/* Literal Constants */
+Letter                   [a-zA-Z]
+
+Identifier               {Letter}({Letter}*[0-9]*_*)*
+Ascending                +
+Descending               -
+
+%%
+
+{Ascending} {
+   return (int)ColumnSortExpressionToken.ASCENDING;
+}
+
+{Descending} {
+   return (int)ColumnSortExpressionToken.DESCENDING;
+}
+
+{Identifier} {
+   yylval.Identifier = yytext;
+   return (int)ColumnSortExpressionToken.IDENTIFIER;
+}
+
+%%

src/DataStreamSuite/Bts.ColumnSortExpressions/GplexBuffers.cs

@@ -0,0 +1,720 @@
+// ==============================================================
+// <auto-generated>
+// This code automatically produced from an embedded resource.
+// Do not edit this file, or it will become incompatible with 
+// the specification from which it was generated.
+// </auto-generated>
+// ==============================================================
+
+using System;
+using System.IO;
+using System.Text;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.Serialization;
+using System.Globalization;
+
+namespace QUT.GplexBuffers
+{
+// Code copied from GPLEX embedded resource
+    [Serializable]
+    internal class BufferException : Exception
+    {
+        public BufferException() { }
+        public BufferException(string message) : base(message) { }
+        public BufferException(string message, Exception innerException)
+            : base(message, innerException) { }
+        protected BufferException(SerializationInfo info, StreamingContext context)
+            : base(info, context) { }
+    }
+
+    internal abstract class ScanBuff
+    {
+        private string fileNm;
+
+        public const int EndOfFile = -1;
+        public const int UnicodeReplacementChar = 0xFFFD;
+
+        public bool IsFile { get { return (fileNm != null); } }
+        public string FileName { get { return fileNm; } set { fileNm = value; } }
+
+        public abstract int Pos { get; set; }
+        public abstract int Read();
+        public virtual void Mark() { }
+
+        public abstract string GetString(int begin, int limit);
+
+        public static ScanBuff GetBuffer(string source)
+        {
+            return new StringBuffer(source);
+        }
+
+        public static ScanBuff GetBuffer(IList<string> source)
+        {
+            return new LineBuffer(source);
+        }
+
+#if (!NOFILES)
+        public static ScanBuff GetBuffer(Stream source)
+        {
+            return new BuildBuffer(source);
+        }
+
+#if (!BYTEMODE)
+        public static ScanBuff GetBuffer(Stream source, int fallbackCodePage)
+        {
+            return new BuildBuffer(source, fallbackCodePage);
+        }
+#endif // !BYTEMODE
+#endif // !NOFILES
+    }
+
+    #region Buffer classes
+
+    // ==============================================================
+    // =====  Definitions for various ScanBuff derived classes   ====
+    // ==============================================================
+    // ===============         String input          ================
+    // ==============================================================
+
+    /// <summary>
+    /// This class reads characters from a single string as
+    /// required, for example, by Visual Studio language services
+    /// </summary>
+    sealed class StringBuffer : ScanBuff
+    {
+        string str;        // input buffer
+        int bPos;          // current position in buffer
+        int sLen;
+
+        public StringBuffer(string source)
+        {
+            this.str = source;
+            this.sLen = source.Length;
+            this.FileName = null;
+        }
+
+        public override int Read()
+        {
+            if (bPos < sLen) return str[bPos++];
+            else if (bPos == sLen) { bPos++; return '\n'; }   // one strike, see new line
+            else { bPos++; return EndOfFile; }                // two strikes and you're out!
+        }
+
+        public override string GetString(int begin, int limit)
+        {
+            //  "limit" can be greater than sLen with the BABEL
+            //  option set.  Read returns a "virtual" EOL if
+            //  an attempt is made to read past the end of the
+            //  string buffer.  Without the guard any attempt 
+            //  to fetch yytext for a token that includes the 
+            //  EOL will throw an index exception.
+            if (limit > sLen) limit = sLen;
+            if (limit <= begin) return "";
+            else return str.Substring(begin, limit - begin);
+        }
+
+        public override int Pos
+        {
+            get { return bPos; }
+            set { bPos = value; }
+        }
+
+        public override string ToString() { return "StringBuffer"; }
+    }
+
+    // ==============================================================
+    //  The LineBuff class contributed by Nigel Horspool, 
+    //  nigelh@cs.uvic.cs
+    // ==============================================================
+
+    sealed class LineBuffer : ScanBuff
+    {
+        IList<string> line;    // list of source lines from a file
+        int numLines;          // number of strings in line list
+        string curLine;        // current line in that list
+        int cLine;             // index of current line in the list
+        int curLen;            // length of current line
+        int curLineStart;      // position of line start in whole file
+        int curLineEnd;        // position of line end in whole file
+        int maxPos;            // max position ever visited in whole file
+        int cPos;              // ordinal number of code in source
+
+        // Constructed from a list of strings, one per source line.
+        // The lines have had trailing '\n' characters removed.
+        public LineBuffer(IList<string> lineList)
+        {
+            line = lineList;
+            numLines = line.Count;
+            cPos = curLineStart = 0;
+            curLine = (numLines > 0 ? line[0] : "");
+            maxPos = curLineEnd = curLen = curLine.Length;
+            cLine = 1;
+            FileName = null;
+        }
+
+        public override int Read()
+        {
+            if (cPos < curLineEnd)
+                return curLine[cPos++ - curLineStart];
+            if (cPos++ == curLineEnd)
+                return '\n';
+            if (cLine >= numLines)
+                return EndOfFile;
+            curLine = line[cLine];
+            curLen = curLine.Length;
+            curLineStart = curLineEnd + 1;
+            curLineEnd = curLineStart + curLen;
+            if (curLineEnd > maxPos)
+                maxPos = curLineEnd;
+            cLine++;
+            return curLen > 0 ? curLine[0] : '\n';
+        }
+
+        // To speed up searches for the line containing a position
+        private int cachedPosition;
+        private int cachedIxdex;
+        private int cachedLineStart;
+
+        // Given a position pos within the entire source, the results are
+        //   ix     -- the index of the containing line
+        //   lstart -- the position of the first character on that line
+        private void findIndex(int pos, out int ix, out int lstart)
+        {
+            if (pos >= cachedPosition)
+            {
+                ix = cachedIxdex; lstart = cachedLineStart;
+            }
+            else
+            {
+                ix = lstart = 0;
+            }
+            while (ix < numLines)
+            {
+                int len = line[ix].Length + 1;
+                if (pos < lstart + len) break;
+                lstart += len;
+                ix++;
+            }
+            cachedPosition = pos;
+            cachedIxdex = ix;
+            cachedLineStart = lstart;
+        }
+
+        public override string GetString(int begin, int limit)
+        {
+            if (begin >= maxPos || limit <= begin) return "";
+            int endIx, begIx, endLineStart, begLineStart;
+            findIndex(begin, out begIx, out begLineStart);
+            int begCol = begin - begLineStart;
+            findIndex(limit, out endIx, out endLineStart);
+            int endCol = limit - endLineStart;
+            string s = line[begIx];
+            if (begIx == endIx)
+            {
+                // the usual case, substring all on one line
+                return (endCol <= s.Length) ?
+                    s.Substring(begCol, endCol - begCol)
+                    : s.Substring(begCol) + "\n";
+            }
+            // the string spans multiple lines, yuk!
+            StringBuilder sb = new StringBuilder();
+            if (begCol < s.Length)
+                sb.Append(s.Substring(begCol));
+            for (; ; )
+            {
+                sb.Append("\n");
+                s = line[++begIx];
+                if (begIx >= endIx) break;
+                sb.Append(s);
+            }
+            if (endCol <= s.Length)
+            {
+                sb.Append(s.Substring(0, endCol));
+            }
+            else
+            {
+                sb.Append(s);
+                sb.Append("\n");
+            }
+            return sb.ToString();
+        }
+
+        public override int Pos
+        {
+            get { return cPos; }
+            set
+            {
+                cPos = value;
+                findIndex(cPos, out cLine, out curLineStart);
+                // cLine should be the *next* line after curLine.
+                curLine = (cLine < numLines ? line[cLine++] : "");
+                curLineEnd = curLineStart + curLine.Length;
+            }
+        }
+
+        public override string ToString() { return "LineBuffer"; }
+    }
+
+#if (!NOFILES)
+    // ==============================================================
+    // =====     class BuildBuff : for unicode text files    ========
+    // ==============================================================
+
+    class BuildBuffer : ScanBuff
+    {
+        // Double buffer for char stream.
+        class BufferElement
+        {
+            StringBuilder bldr = new StringBuilder();
+            StringBuilder next = new StringBuilder();
+            int minIx;
+            int maxIx;
+            int brkIx;
+            bool appendToNext;
+
+            internal BufferElement() { }
+
+            internal int MaxIndex { get { return maxIx; } }
+            // internal int MinIndex { get { return minIx; } }
+
+            internal char this[int index]
+            {
+                get
+                {
+                    if (index < minIx || index >= maxIx)
+                        throw new BufferException("Index was outside data buffer");
+                    else if (index < brkIx)
+                        return bldr[index - minIx];
+                    else
+                        return next[index - brkIx];
+                }
+            }
+
+            internal void Append(char[] block, int count)
+            {
+                maxIx += count;
+                if (appendToNext)
+                    this.next.Append(block, 0, count);
+                else
+                {
+                    this.bldr.Append(block, 0, count);
+                    brkIx = maxIx;
+                    appendToNext = true;
+                }
+            }
+
+            internal string GetString(int start, int limit)
+            {
+                if (limit <= start)
+                    return "";
+                if (start >= minIx && limit <= maxIx)
+                    if (limit < brkIx) // String entirely in bldr builder
+                        return bldr.ToString(start - minIx, limit - start);
+                    else if (start >= brkIx) // String entirely in next builder
+                        return next.ToString(start - brkIx, limit - start);
+                    else // Must do a string-concatenation
+                        return
+                            bldr.ToString(start - minIx, brkIx - start) +
+                            next.ToString(0, limit - brkIx);
+                else
+                    throw new BufferException("String was outside data buffer");
+            }
+
+            internal void Mark(int limit)
+            {
+                if (limit > brkIx + 16) // Rotate blocks
+                {
+                    StringBuilder temp = bldr;
+                    bldr = next;
+                    next = temp;
+                    next.Length = 0;
+                    minIx = brkIx;
+                    brkIx = maxIx;
+                }
+            }
+        }
+
+        BufferElement data = new BufferElement();
+
+        int bPos;            // Postion index in the StringBuilder
+        BlockReader NextBlk; // Delegate that serves char-arrays;
+
+        private string EncodingName
+        {
+            get
+            {
+                StreamReader rdr = NextBlk.Target as StreamReader;
+                return (rdr == null ? "raw-bytes" : rdr.CurrentEncoding.BodyName);
+            }
+        }
+
+        public BuildBuffer(Stream stream)
+        {
+            FileStream fStrm = (stream as FileStream);
+            if (fStrm != null) FileName = fStrm.Name;
+            NextBlk = BlockReaderFactory.Raw(stream);
+        }
+
+#if (!BYTEMODE)
+        public BuildBuffer(Stream stream, int fallbackCodePage)
+        {
+            FileStream fStrm = (stream as FileStream);
+            if (fStrm != null) FileName = fStrm.Name;
+            NextBlk = BlockReaderFactory.Get(stream, fallbackCodePage);
+        }
+#endif
+
+        /// <summary>
+        /// Marks a conservative lower bound for the buffer,
+        /// allowing space to be reclaimed.  If an application 
+        /// needs to call GetString at arbitrary past locations 
+        /// in the input stream, Mark() is not called.
+        /// </summary>
+        public override void Mark() { data.Mark(bPos - 2); }
+
+        public override int Pos
+        {
+            get { return bPos; }
+            set { bPos = value; }
+        }
+
+
+        /// <summary>
+        /// Read returns the ordinal number of the next char, or 
+        /// EOF (-1) for an end of stream.  Note that the next
+        /// code point may require *two* calls of Read().
+        /// </summary>
+        /// <returns></returns>
+        public override int Read()
+        {
+            //
+            //  Characters at positions 
+            //  [data.offset, data.offset + data.bldr.Length)
+            //  are available in data.bldr.
+            //
+            if (bPos < data.MaxIndex)
+            {
+                // ch0 cannot be EOF
+                return (int)data[bPos++];
+            }
+            else // Read from underlying stream
+            {
+                // Experimental code, blocks of page size
+                char[] chrs = new char[4096];
+                int count = NextBlk(chrs, 0, 4096);
+                if (count == 0)
+                    return EndOfFile;
+                else
+                {
+                    data.Append(chrs, count);
+                    return (int)data[bPos++];
+                }
+            }
+        }
+
+        public override string GetString(int begin, int limit)
+        {
+            return data.GetString(begin, limit);
+        }
+
+        public override string ToString()
+        {
+            return "StringBuilder buffer, encoding: " + this.EncodingName;
+        }
+    }
+
+    // =============== End ScanBuff-derived classes ==================
+
+    internal delegate int BlockReader(char[] block, int index, int number);
+
+    // A delegate factory, serving up a delegate that
+    // reads a block of characters from the underlying
+    // encoded stream, via a StreamReader object.
+    //
+    internal static class BlockReaderFactory
+    {
+        public static BlockReader Raw(Stream stream)
+        {
+            return delegate(char[] block, int index, int number)
+            {
+                byte[] b = new byte[number];
+                int count = stream.Read(b, 0, number);
+                int i = 0;
+                int j = index;
+                for (; i < count; i++, j++)
+                    block[j] = (char)b[i];
+                return count;
+            };
+        }
+
+#if (!BYTEMODE)
+        public static BlockReader Get(Stream stream, int fallbackCodePage)
+        {
+            Encoding encoding;
+            int preamble = Preamble(stream);
+
+            if (preamble != 0)  // There is a valid BOM here!
+                encoding = Encoding.GetEncoding(preamble);
+            else if (fallbackCodePage == -1) // Fallback is "raw" bytes
+                return Raw(stream);
+            else if (fallbackCodePage != -2) // Anything but "guess"
+                encoding = Encoding.GetEncoding(fallbackCodePage);
+            else // This is the "guess" option
+            {
+                int guess = new Guesser(stream).GuessCodePage();
+                stream.Seek(0, SeekOrigin.Begin);
+                if (guess == -1) // ==> this is a 7-bit file
+                    encoding = Encoding.ASCII;
+                else if (guess == 65001)
+                    encoding = Encoding.UTF8;
+                else             // ==> use the machine default
+                    encoding = Encoding.Default;
+            }
+            StreamReader reader = new StreamReader(stream, encoding);
+            return reader.Read;
+        }
+
+        static int Preamble(Stream stream)
+        {
+            int b0 = stream.ReadByte();
+            int b1 = stream.ReadByte();
+
+            if (b0 == 0xfe && b1 == 0xff)
+                return 1201; // UTF16BE
+            if (b0 == 0xff && b1 == 0xfe)
+                return 1200; // UTF16LE
+
+            int b2 = stream.ReadByte();
+            if (b0 == 0xef && b1 == 0xbb && b2 == 0xbf)
+                return 65001; // UTF8
+            //
+            // There is no unicode preamble, so we
+            // return denoter for the machine default.
+            //
+            stream.Seek(0, SeekOrigin.Begin);
+            return 0;
+        }
+#endif // !BYTEMODE
+    }
+#endif // !NOFILES
+    #endregion Buffer classes
+
+    // ==============================================================
+    // ============      class CodePageHandling         =============
+    // ==============================================================
+#if (!NOFILES)
+    public static class CodePageHandling
+    {
+        public static int GetCodePage(string option)
+        {
+            string command = option.ToUpperInvariant();
+            if (command.StartsWith("CodePage:", StringComparison.OrdinalIgnoreCase))
+                command = command.Substring(9);
+            try
+            {
+                if (command.Equals("RAW"))
+                    return -1;
+                else if (command.Equals("GUESS"))
+                    return -2;
+                else if (command.Equals("DEFAULT"))
+                    return 0;
+                else if (char.IsDigit(command[0]))
+                    return int.Parse(command, CultureInfo.InvariantCulture);
+                else
+                {
+                    Encoding enc = Encoding.GetEncoding(command);
+                    return enc.CodePage;
+                }
+            }
+            catch (FormatException)
+            {
+                Console.Error.WriteLine(
+                    "Invalid format \"{0}\", using machine default", option);
+            }
+            catch (ArgumentException)
+            {
+                Console.Error.WriteLine(
+                    "Unknown code page \"{0}\", using machine default", option);
+            }
+            return 0;
+        }
+    }
+#region guesser
+#if (!BYTEMODE)
+    // ==============================================================
+    // ============          Encoding Guesser           =============
+    // ==============================================================
+
+    /// <summary>
+    /// This class provides a simple finite state automaton that
+    /// scans the file looking for (1) valid UTF-8 byte patterns,
+    /// (2) bytes >= 0x80 which are not part of a UTF-8 sequence.
+    /// The method then guesses whether it is UTF-8 or maybe some 
+    /// local machine default encoding.  This works well for the
+    /// various Latin encodings.
+    /// </summary>
+    internal class Guesser
+    {
+        ScanBuff buffer;
+
+        public int GuessCodePage() { return Scan(); }
+
+        const int maxAccept = 10;
+        const int initial = 0;
+        const int eofNum = 0;
+        const int goStart = -1;
+        const int INITIAL = 0;
+        const int EndToken = 0;
+
+        #region user code
+        /* 
+         *  Reads the bytes of a file to determine if it is 
+         *  UTF-8 or a single-byte code page file.
+         */
+        public long utfX;
+        public long uppr;
+        #endregion user code
+
+        int state;
+        int currentStart = startState[0];
+        int code;
+
+        #region ScannerTables
+        static int[] startState = new int[] { 11, 0 };
+
+        #region CharacterMap
+        static sbyte[] map = new sbyte[256] {
+/*     '\0' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*   '\x10' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*   '\x20' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      '0' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      '@' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      'P' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      '`' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*      'p' */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+/*   '\x80' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\x90' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\xA0' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\xB0' */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
+/*   '\xC0' */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+/*   '\xD0' */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+/*   '\xE0' */ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 
+/*   '\xF0' */ 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5 };
+        #endregion
+
+        static sbyte[][] nextState = new sbyte[][] {
+            new sbyte[] {0, 0, 0, 0, 0, 0},
+            new sbyte[] {-1, -1, 10, -1, -1, -1},
+            new sbyte[] {-1, -1, -1, -1, -1, -1},
+            new sbyte[] {-1, -1, 8, -1, -1, -1},
+            new sbyte[] {-1, -1, 5, -1, -1, -1},
+            new sbyte[] {-1, -1, 6, -1, -1, -1},
+            new sbyte[] {-1, -1, 7, -1, -1, -1},
+            null,
+            new sbyte[] {-1, -1, 9, -1, -1, -1},
+            null,
+            null,
+            new sbyte[] {-1, 1, 2, 3, 4, 2}
+        };
+
+
+        [SuppressMessage("Microsoft.Performance", "CA1810:InitializeReferenceTypeStaticFieldsInline")]
+        // Reason for suppression: cannot have self-reference in array initializer.
+        static Guesser()
+        {
+            nextState[7] = nextState[2];
+            nextState[9] = nextState[2];
+            nextState[10] = nextState[2];
+        }
+
+        int NextState()
+        {
+            if (code == ScanBuff.EndOfFile)
+                return eofNum;
+            else
+                return nextState[state][map[code]];
+        }
+        #endregion
+
+        public Guesser(System.IO.Stream file) { SetSource(file); }
+
+        public void SetSource(System.IO.Stream source)
+        {
+            this.buffer = new BuildBuffer(source);
+            code = buffer.Read();
+        }
+
+        int Scan()
+        {
+            for (; ; )
+            {
+                int next;
+                state = currentStart;
+                while ((next = NextState()) == goStart)
+                    code = buffer.Read();
+
+                state = next;
+                code = buffer.Read();
+
+                while ((next = NextState()) > eofNum)
+                {
+                    state = next;
+                    code = buffer.Read();
+                }
+                if (state <= maxAccept)
+                {
+                    #region ActionSwitch
+#pragma warning disable 162
+                    switch (state)
+                    {
+                        case eofNum:
+                            switch (currentStart)
+                            {
+                                case 11:
+                                    if (utfX == 0 && uppr == 0) return -1; /* raw ascii */
+                                    else if (uppr * 10 > utfX) return 0;   /* default code page */
+                                    else return 65001;                     /* UTF-8 encoding */
+                                    break;
+                            }
+                            return EndToken;
+                        case 1: // Recognized '{Upper128}',	Shortest string "\xC0"
+                        case 2: // Recognized '{Upper128}',	Shortest string "\x80"
+                        case 3: // Recognized '{Upper128}',	Shortest string "\xE0"
+                        case 4: // Recognized '{Upper128}',	Shortest string "\xF0"
+                            uppr++;
+                            break;
+                        case 5: // Recognized '{Utf8pfx4}{Utf8cont}',	Shortest string "\xF0\x80"
+                            uppr += 2;
+                            break;
+                        case 6: // Recognized '{Utf8pfx4}{Utf8cont}{2}',	Shortest string "\xF0\x80\x80"
+                            uppr += 3;
+                            break;
+                        case 7: // Recognized '{Utf8pfx4}{Utf8cont}{3}',	Shortest string "\xF0\x80\x80\x80"
+                            utfX += 3;
+                            break;
+                        case 8: // Recognized '{Utf8pfx3}{Utf8cont}',	Shortest string "\xE0\x80"
+                            uppr += 2;
+                            break;
+                        case 9: // Recognized '{Utf8pfx3}{Utf8cont}{2}',	Shortest string "\xE0\x80\x80"
+                            utfX += 2;
+                            break;
+                        case 10: // Recognized '{Utf8pfx2}{Utf8cont}',	Shortest string "\xC0\x80"
+                            utfX++;
+                            break;
+                        default:
+                            break;
+                    }
+#pragma warning restore 162
+                    #endregion
+                }
+            }
+        }
+    } // end class Guesser
+    
+#endif // !BYTEMODE
+#endregion
+#endif // !NOFILES
+
+// End of code copied from embedded resource
+}

src/DataStreamSuite/Bts.ColumnSortExpressions/ShiftReduceParserCode.cs

@@ -0,0 +1,884 @@
+// ==============================================================
+// <auto-generated>
+// This code automatically produced from an embedded resource.
+// Do not edit this file, or it will become incompatible with 
+// the specification from which it was generated.
+// </auto-generated>
+// ==============================================================
+
+// Gardens Point Parser Generator
+// Copyright (c) Wayne Kelly, QUT 2005-2010
+// (see accompanying GPPGcopyright.rtf)
+
+using System;
+using System.Text;
+using System.Globalization;
+using System.Collections.Generic;
+using System.Runtime.Serialization;
+using System.Diagnostics.CodeAnalysis;
+
+namespace QUT.Gppg {
+    /// <summary>
+    /// Abstract class for GPPG shift-reduce parsers.
+    /// Parsers generated by GPPG derive from this base
+    /// class, overriding the abstract Initialize() and
+    /// DoAction() methods.
+    /// </summary>
+    /// <typeparam name="TValue">Semantic value type</typeparam>
+    /// <typeparam name="TSpan">Location type</typeparam>
+#if EXPORT_GPPG
+    public abstract class ShiftReduceParser<TValue, TSpan>
+#else
+    internal abstract class ShiftReduceParser<TValue, TSpan>
+#endif
+ where TSpan : IMerge<TSpan>, new() {
+        private AbstractScanner<TValue, TSpan> scanner;
+        /// <summary>
+        /// The abstract scanner for this parser.
+        /// </summary>
+        protected AbstractScanner<TValue, TSpan> Scanner {
+            get { return scanner; }
+            set { scanner = value; }
+        }
+
+        /// <summary>
+        /// Constructor for base class
+        /// </summary>
+        /// <param name="scanner">Scanner instance for this parser</param>
+        protected ShiftReduceParser( AbstractScanner<TValue, TSpan> scanner ) {
+            this.scanner = scanner;
+        }
+
+        // ==============================================================
+        //                    TECHNICAL EXPLANATION.
+        //   Why the next two fields are not exposed via properties.
+        // ==============================================================
+        // These fields are of the generic parameter types, and are
+        // frequently instantiated as struct types in derived classes.
+        // Semantic actions are defined in the derived classes and refer
+        // to instance fields of these structs.  In such cases the code
+        // "get_CurrentSemanticValue().myField = blah;" will fail since
+        // the getter pushes the value of the field, not the reference.
+        // So, in the presence of properties, gppg would need to encode
+        // such field accesses as ... 
+        //  "tmp = get_CurrentSemanticValue(); // Fetch value
+        //   tmp.myField = blah;               // update
+        //   set_CurrentSemanticValue(tmp); "  // Write update back.
+        // There is no issue if TValue is restricted to be a ref type.
+        // The same explanation applies to scanner.yylval.
+        // ==============================================================
+        /// <summary>
+        /// The current value of the "$$" symbolic variable in the parser
+        /// </summary>
+        [SuppressMessage( "Microsoft.Design", "CA1051:DoNotDeclareVisibleInstanceFields" )]
+        protected TValue CurrentSemanticValue;
+
+        /// <summary>
+        /// The current value of the "@$" symbolic variable in the parser
+        /// </summary>
+        [SuppressMessage( "Microsoft.Design", "CA1051:DoNotDeclareVisibleInstanceFields" )]
+        protected TSpan CurrentLocationSpan;
+        protected int NextToken;
+
+        private TSpan LastSpan;
+        private State FsaState;
+        private bool recovering;
+        private int tokensSinceLastError;
+
+        private PushdownPrefixState<State> StateStack = new PushdownPrefixState<State>();
+        private PushdownPrefixState<TValue> valueStack = new PushdownPrefixState<TValue>();
+        private PushdownPrefixState<TSpan> locationStack = new PushdownPrefixState<TSpan>();
+
+        /// <summary>
+        /// The stack of semantic value (YYSTYPE) values.
+        /// </summary>
+        protected PushdownPrefixState<TValue> ValueStack { get { return valueStack; } }
+
+        /// <summary>
+        /// The stack of location value (YYLTYPE) varlues.
+        /// </summary>
+        protected PushdownPrefixState<TSpan> LocationStack { get { return locationStack; } }
+
+        private int errorToken;
+        private int endOfFileToken;
+        private string[] nonTerminals;
+        private State[] states;
+        private Rule[] rules;
+
+        /// <summary>
+        /// Initialization method to allow derived classes
+        /// to insert the rule list into this base class.
+        /// </summary>
+        /// <param name="rules">The array of Rule objects</param>
+        protected void InitRules( Rule[] rules ) { this.rules = rules; }
+
+        /// <summary>
+        /// Initialization method to allow derived classes to
+        /// insert the states table into this base class.
+        /// </summary>
+        /// <param name="states">The pre-initialized states table</param>
+        protected void InitStates( State[] states ) { this.states = states; }
+
+        /// <summary>
+        /// OBSOLETE FOR VERSION 1.4.0
+        /// </summary>
+        /// <param name="size"></param>
+        protected void InitStateTable( int size ) { states = new State[size]; }
+
+        /// <summary>
+        /// Initialization method to allow derived classes
+        /// to insert the special value for the error and EOF tokens.
+        /// </summary>
+        /// <param name="err">The error state ordinal</param>
+        /// <param name="end">The EOF stat ordinal</param>
+        protected void InitSpecialTokens( int err, int end ) {
+            errorToken = err;
+            endOfFileToken = end;
+        }
+
+        /// <summary>
+        /// Initialization method to allow derived classes to
+        /// insert the non-terminal symbol names into this base class.
+        /// </summary>
+        /// <param name="names">Non-terminal symbol names</param>
+        protected void InitNonTerminals( string[] names ) { nonTerminals = names; }
+
+        #region YYAbort, YYAccept etcetera.
+        [Serializable]
+        [SuppressMessage( "Microsoft.Design", "CA1064:ExceptionsShouldBePublic" )]
+        // Reason for FxCop message suppression -
+        // This exception cannot escape from the local context
+        private class AcceptException : Exception {
+            internal AcceptException() { }
+            protected AcceptException( SerializationInfo i, StreamingContext c ) : base( i, c ) { }
+        }
+        [Serializable]
+        [SuppressMessage( "Microsoft.Design", "CA1064:ExceptionsShouldBePublic" )]
+        // Reason for FxCop message suppression -
+        // This exception cannot escape from the local context
+        private class AbortException : Exception {
+            internal AbortException() { }
+            protected AbortException( SerializationInfo i, StreamingContext c ) : base( i, c ) { }
+        }
+        [Serializable]
+        [SuppressMessage( "Microsoft.Design", "CA1064:ExceptionsShouldBePublic" )]
+        // Reason for FxCop message suppression -
+        // This exception cannot escape from the local context
+        private class ErrorException : Exception {
+            internal ErrorException() { }
+            protected ErrorException( SerializationInfo i, StreamingContext c ) : base( i, c ) { }
+        }
+
+        // The following methods are only called from within
+        // a semantic action. The thrown exceptions can never
+        // propagate outside the ShiftReduceParser class in 
+        // which they are nested.
+
+        /// <summary>
+        /// Force parser to terminate, returning "true"
+        /// </summary>
+        protected static void YYAccept() { throw new AcceptException(); }
+
+        /// <summary>
+        /// Force parser to terminate, returning "false"
+        /// </summary>
+        protected static void YYAbort() { throw new AbortException(); }
+
+        /// <summary>
+        /// Force parser to terminate, returning
+        /// "false" if error recovery fails.
+        /// </summary>
+        protected static void YYError() { throw new ErrorException(); }
+
+        /// <summary>
+        /// Check if parser in error recovery state.
+        /// </summary>
+        protected bool YYRecovering { get { return recovering; } }
+        #endregion
+
+        /// <summary>
+        /// Abstract base method. ShiftReduceParser calls this
+        /// to initialize the base class data structures.  Concrete
+        /// parser classes must override this method.
+        /// </summary>
+        protected abstract void Initialize();
+
+        /// <summary>
+        /// Main entry point of the Shift-Reduce Parser.
+        /// </summary>
+        /// <returns>True if parse succeeds, else false for
+        /// unrecoverable errors</returns>
+        public bool Parse() {
+            Initialize();	// allow derived classes to instantiate rules, states and nonTerminals
+
+            NextToken = 0;
+            FsaState = states[0];
+
+            StateStack.Push( FsaState );
+            valueStack.Push( CurrentSemanticValue );
+            LocationStack.Push( CurrentLocationSpan );
+
+            while (true) {
+#if TRACE_ACTIONS
+                Console.Error.WriteLine("Entering state {0} ", FsaState.number);
+                DisplayStack();
+#endif
+                int action = FsaState.defaultAction;
+
+                if (FsaState.ParserTable != null) {
+                    if (NextToken == 0) {
+                        // We save the last token span, so that the location span
+                        // of production right hand sides that begin or end with a
+                        // nullable production will be correct.
+                        LastSpan = scanner.yylloc;
+                        NextToken = scanner.yylex();
+#if TRACE_ACTIONS
+                       Console.Error.WriteLine( "Reading: Next token is {0}", TerminalToString( NextToken ) );
+#endif
+                    }
+#if TRACE_ACTIONS
+                    else 
+                        Console.Error.WriteLine( "Next token is still {0}", TerminalToString( NextToken ) );
+#endif
+                    if (FsaState.ParserTable.ContainsKey( NextToken ))
+                        action = FsaState.ParserTable[NextToken];
+                }
+
+                if (action > 0)         // shift
+                {
+                    Shift( action );
+                }
+                else if (action < 0)   // reduce
+                {
+                    try {
+                        Reduce( -action );
+                        if (action == -1)	// accept
+                            return true;
+                    }
+                    catch (AbortException) {
+                            return false;
+                    }
+                    catch (AcceptException) {
+                        return true;
+                    }
+                    catch (ErrorException) {
+                        if (!ErrorRecovery())
+                            return false;
+                        else
+                            throw;  // Rethrow x, preserving information.
+                    }
+                }
+                else if (action == 0 && !ErrorRecovery()) // error
+                    return false;
+            }
+        }
+
+        private void Shift( int stateIndex ) {
+#if TRACE_ACTIONS
+				Console.Error.Write("Shifting token {0}, ", TerminalToString(NextToken));
+#endif
+            FsaState = states[stateIndex];
+
+            valueStack.Push( scanner.yylval );
+            StateStack.Push( FsaState );
+            LocationStack.Push( scanner.yylloc );
+
+            if (recovering) {
+                if (NextToken != errorToken)
+                    tokensSinceLastError++;
+
+                if (tokensSinceLastError > 5)
+                    recovering = false;
+            }
+
+            if (NextToken != endOfFileToken)
+                NextToken = 0;
+        }
+
+        private void Reduce( int ruleNumber ) {
+#if TRACE_ACTIONS
+				DisplayRule(ruleNumber);
+#endif
+            Rule rule = rules[ruleNumber];
+            int rhLen = rule.RightHandSide.Length;
+            //
+            //  Default actions for unit productions.
+            //
+            if (rhLen == 1) {
+                CurrentSemanticValue = valueStack.TopElement();   // Default action: $$ = $1;
+                CurrentLocationSpan = LocationStack.TopElement(); // Default action "@$ = @1;
+            }
+            else if (rhLen == 0) {
+                // Create a new blank value.
+                // Explicit semantic action may mutate this value
+                CurrentSemanticValue = default( TValue );
+                // The location span for an empty production will start with the
+                // beginning of the next lexeme, and end with the finish of the
+                // previous lexeme.  This gives the correct behaviour when this
+                // nonsense value is used in later Merge operations.
+                CurrentLocationSpan = (scanner.yylloc != null && LastSpan != null ?
+                    scanner.yylloc.Merge( LastSpan ) :
+                    default( TSpan ));
+            }
+            else {
+                // Default action: $$ = $1;
+                CurrentSemanticValue = valueStack[LocationStack.Depth - rhLen];
+                //  Default action "@$ = @1.Merge(@N)" for location info.
+                TSpan at1 = LocationStack[LocationStack.Depth - rhLen];
+                TSpan atN = LocationStack[LocationStack.Depth - 1];
+                CurrentLocationSpan =
+                    ((at1 != null && atN != null) ? at1.Merge( atN ) : default( TSpan ));
+            }
+
+            DoAction( ruleNumber );
+
+            for (int i = 0; i < rule.RightHandSide.Length; i++) {
+                StateStack.Pop();
+                valueStack.Pop();
+                LocationStack.Pop();
+            }
+            FsaState = StateStack.TopElement();
+
+            if (FsaState.Goto.ContainsKey( rule.LeftHandSide ))
+                FsaState = states[FsaState.Goto[rule.LeftHandSide]];
+
+            StateStack.Push( FsaState );
+            valueStack.Push( CurrentSemanticValue );
+            LocationStack.Push( CurrentLocationSpan );
+        }
+
+        /// <summary>
+        /// Execute the selected action from array.
+        /// Must be overriden in derived classes.
+        /// </summary>
+        /// <param name="actionNumber">Index of the action to perform</param>
+        protected abstract void DoAction( int actionNumber );
+
+        private bool ErrorRecovery() {
+            bool discard;
+
+            if (!recovering) // if not recovering from previous error
+                ReportError();
+
+            if (!FindErrorRecoveryState())
+                return false;
+            //
+            //  The interim fix for the "looping in error recovery"
+            //  artifact involved moving the setting of the recovering 
+            //  bool until after invalid tokens have been discarded.
+            //
+            ShiftErrorToken();
+            discard = DiscardInvalidTokens();
+            recovering = true;
+            tokensSinceLastError = 0;
+            return discard;
+        }
+
+        private void ReportError() {
+            StringBuilder errorMsg = new StringBuilder();
+            errorMsg.AppendFormat( "Syntax error, unexpected {0}", TerminalToString( NextToken ) );
+
+            if (FsaState.ParserTable.Count < 7) {
+                bool first = true;
+                foreach (int terminal in FsaState.ParserTable.Keys) {
+                    if (first)
+                        errorMsg.Append( ", expecting " );
+                    else
+                        errorMsg.Append( ", or " );
+
+                    errorMsg.Append( TerminalToString( terminal ) );
+                    first = false;
+                }
+            }
+            scanner.yyerror( errorMsg.ToString() );
+        }
+
+        private void ShiftErrorToken() {
+            int old_next = NextToken;
+            NextToken = errorToken;
+
+            Shift( FsaState.ParserTable[NextToken] );
+
+#if TRACE_ACTIONS
+				Console.Error.WriteLine("Entering state {0} ", FsaState.number);
+#endif
+            NextToken = old_next;
+        }
+
+        private bool FindErrorRecoveryState() {
+            while (true)    // pop states until one found that accepts error token
+            {
+                if (FsaState.ParserTable != null &&
+                    FsaState.ParserTable.ContainsKey( errorToken ) &&
+                    FsaState.ParserTable[errorToken] > 0) // shift
+                    return true;
+
+#if TRACE_ACTIONS
+					Console.Error.WriteLine("Error: popping state {0}", StateStack.TopElement().number);
+#endif
+                StateStack.Pop();
+                valueStack.Pop();
+                LocationStack.Pop();
+
+#if TRACE_ACTIONS
+			    DisplayStack();
+#endif
+                if (StateStack.IsEmpty()) {
+#if TRACE_ACTIONS
+                        Console.Error.WriteLine("Aborting: didn't find a state that accepts error token");
+#endif
+                    return false;
+                }
+                else
+                    FsaState = StateStack.TopElement();
+            }
+        }
+
+        private bool DiscardInvalidTokens() {
+
+            int action = FsaState.defaultAction;
+
+            if (FsaState.ParserTable != null) {
+                // Discard tokens until find one that works ...
+                while (true) {
+                    if (NextToken == 0) {
+#if TRACE_ACTIONS
+                            Console.Error.Write("Reading a token: ");
+#endif
+                        NextToken = scanner.yylex();
+                    }
+#if TRACE_ACTIONS
+                        Console.Error.WriteLine("Next token is {0}", TerminalToString(NextToken));
+#endif
+                    if (NextToken == endOfFileToken)
+                        return false;
+
+                    if (FsaState.ParserTable.ContainsKey( NextToken ))
+                        action = FsaState.ParserTable[NextToken];
+
+                    if (action != 0)
+                        return true;
+                    else {
+#if TRACE_ACTIONS
+                            Console.Error.WriteLine("Error: Discarding {0}", TerminalToString(NextToken));
+#endif
+                        NextToken = 0;
+                    }
+                }
+            }
+            else if (recovering && tokensSinceLastError == 0) {
+                // 
+                //  Boolean recovering is not set until after the first
+                //  error token has been shifted.  Thus if we get back 
+                //  here with recovering set and no tokens read we are
+                //  looping on the same error recovery action.  This 
+                //  happens if current_state.ParserTable is null because
+                //  the state has an LR(0) reduction, but not all
+                //  lookahead tokens are valid.  This only occurs for
+                //  error productions that *end* on "error".
+                //
+                //  This action discards tokens one at a time until
+                //  the looping stops.  Another attack would be to always
+                //  use the LALR(1) table if a production ends on "error"
+                //
+#if TRACE_ACTIONS
+                    Console.Error.WriteLine("Error: panic discard of {0}", TerminalToString(NextToken));
+#endif
+                if (NextToken == endOfFileToken)
+                    return false;
+                NextToken = 0;
+                return true;
+            }
+            else
+                return true;
+        }
+
+        /// <summary>
+        /// Traditional YACC method.  Discards the next input token.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yyclearin" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yyclearin" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        protected void yyclearin() { NextToken = 0; }
+
+        /// <summary>
+        /// Tradional YACC method. Clear the "recovering" flag.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yyerrok" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yyerrok" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        protected void yyerrok() { recovering = false; }
+
+        /// <summary>
+        /// OBSOLETE FOR VERSION 1.4.0
+        /// Method used by derived types to insert new
+        /// state instances in the "states" array.
+        /// </summary>
+        /// <param name="stateNumber">index of the state</param>
+        /// <param name="state">data for the state</param>
+        protected void AddState( int stateNumber, State state ) {
+            states[stateNumber] = state;
+            state.number = stateNumber;
+        }
+
+        private void DisplayStack() {
+            Console.Error.Write( "State stack is now:" );
+            for (int i = 0; i < StateStack.Depth; i++)
+                Console.Error.Write( " {0}", StateStack[i].number );
+            Console.Error.WriteLine();
+        }
+
+        private void DisplayRule( int ruleNumber ) {
+            Console.Error.Write( "Reducing stack by rule {0}, ", ruleNumber );
+            DisplayProduction( rules[ruleNumber] );
+        }
+
+        private void DisplayProduction( Rule rule ) {
+            if (rule.RightHandSide.Length == 0)
+                Console.Error.Write( "/* empty */ " );
+            else
+                foreach (int symbol in rule.RightHandSide)
+                    Console.Error.Write( "{0} ", SymbolToString( symbol ) );
+
+            Console.Error.WriteLine( "-> {0}", SymbolToString( rule.LeftHandSide ) );
+        }
+
+        /// <summary>
+        /// Abstract state class naming terminal symbols.
+        /// This is overridden by derived classes with the
+        /// name (or alias) to be used in error messages.
+        /// </summary>
+        /// <param name="terminal">The terminal ordinal</param>
+        /// <returns></returns>
+        protected abstract string TerminalToString( int terminal );
+
+        private string SymbolToString( int symbol ) {
+            if (symbol < 0)
+                return nonTerminals[-symbol - 1];
+            else
+                return TerminalToString( symbol );
+        }
+
+        /// <summary>
+        /// Return text representation of argument character
+        /// </summary>
+        /// <param name="input">The character to convert</param>
+        /// <returns>String representation of the character</returns>
+        protected static string CharToString( char input ) {
+            switch (input) {
+                case '\a': return @"'\a'";
+                case '\b': return @"'\b'";
+                case '\f': return @"'\f'";
+                case '\n': return @"'\n'";
+                case '\r': return @"'\r'";
+                case '\t': return @"'\t'";
+                case '\v': return @"'\v'";
+                case '\0': return @"'\0'";
+                default: return string.Format( CultureInfo.InvariantCulture, "'{0}'", input );
+            }
+        }
+    }
+
+    /// <summary>
+    /// Classes implementing this interface must supply a
+    /// method that merges two location objects to return
+    /// a new object of the same type.
+    /// GPPG-generated parsers have the default location
+    /// action equivalent to "@$ = @1.Merge(@N);" where N
+    /// is the right-hand-side length of the production.
+    /// </summary>
+    /// <typeparam name="TSpan">The Location type</typeparam>
+#if EXPORT_GPPG
+    public interface IMerge<TSpan>
+#else
+    internal interface IMerge<TSpan>
+#endif
+ {
+        /// <summary>
+        /// Interface method that creates a location object from
+        /// the current and last object.  Typically used to create
+        /// a location object extending from the start of the @1
+        /// object to the end of the @N object.
+        /// </summary>
+        /// <param name="last">The lexically last object to merge</param>
+        /// <returns>The merged location object</returns>
+        TSpan Merge( TSpan last );
+    }
+
+    /// <summary>
+    /// This is the default class that carries location
+    /// information from the scanner to the parser.
+    /// If you don't declare "%YYLTYPE Foo" the parser
+    /// will expect to deal with this type.
+    /// </summary>
+#if EXPORT_GPPG
+    public class LexLocation : IMerge<LexLocation>
+#else
+    [SuppressMessage( "Microsoft.Performance", "CA1812:AvoidUninstantiatedInternalClasses" )]
+    internal class LexLocation : IMerge<LexLocation>
+#endif
+ {
+        private int startLine;   // start line
+        private int startColumn; // start column
+        private int endLine;     // end line
+        private int endColumn;   // end column
+
+        /// <summary>
+        /// The line at which the text span starts.
+        /// </summary>
+        public int StartLine { get { return startLine; } }
+
+        /// <summary>
+        /// The column at which the text span starts.
+        /// </summary>
+        public int StartColumn { get { return startColumn; } }
+
+        /// <summary>
+        /// The line on which the text span ends.
+        /// </summary>
+        public int EndLine { get { return endLine; } }
+
+        /// <summary>
+        /// The column of the first character
+        /// beyond the end of the text span.
+        /// </summary>
+        public int EndColumn { get { return endColumn; } }
+
+        /// <summary>
+        /// Default no-arg constructor.
+        /// </summary>
+        public LexLocation() { }
+
+        /// <summary>
+        /// Constructor for text-span with given start and end.
+        /// </summary>
+        /// <param name="sl">start line</param>
+        /// <param name="sc">start column</param>
+        /// <param name="el">end line </param>
+        /// <param name="ec">end column</param>
+        public LexLocation( int sl, int sc, int el, int ec ) { startLine = sl; startColumn = sc; endLine = el; endColumn = ec; }
+
+        /// <summary>
+        /// Create a text location which spans from the 
+        /// start of "this" to the end of the argument "last"
+        /// </summary>
+        /// <param name="last">The last location in the result span</param>
+        /// <returns>The merged span</returns>
+        public LexLocation Merge( LexLocation last ) { return new LexLocation( this.startLine, this.startColumn, last.endLine, last.endColumn ); }
+    }
+
+    /// <summary>
+    /// Abstract scanner class that GPPG expects its scanners to 
+    /// extend.
+    /// </summary>
+    /// <typeparam name="TValue">Semantic value type YYSTYPE</typeparam>
+    /// <typeparam name="TSpan">Source location type YYLTYPE</typeparam>
+#if EXPORT_GPPG
+    public abstract class AbstractScanner<TValue, TSpan>
+#else
+    internal abstract class AbstractScanner<TValue, TSpan>
+#endif
+ where TSpan : IMerge<TSpan> {
+        /// <summary>
+        /// Lexical value optionally set by the scanner. The value
+        /// is of the %YYSTYPE type declared in the parser spec.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Design", "CA1051:DoNotDeclareVisibleInstanceFields" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yylval" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yylval" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        // A field must be declared for this value of parametric type,
+        // since it may be instantiated by a value struct.  If it were 
+        // implemented as a property, machine generated code in derived
+        // types would not be able to select on the returned value.
+#pragma warning disable 649
+        public TValue yylval;                     // Lexical value: set by scanner
+#pragma warning restore 649
+
+        /// <summary>
+        /// Current scanner location property. The value is of the
+        /// type declared by %YYLTYPE in the parser specification.
+        /// </summary>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yylloc" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yylloc" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        public virtual TSpan yylloc {
+            get { return default( TSpan ); }       // Empty implementation allowing
+            set { /* skip */ }                   // yylloc to be ignored entirely.
+        }
+
+        /// <summary>
+        /// Main call point for LEX-like scanners.  Returns an int
+        /// corresponding to the token recognized by the scanner.
+        /// </summary>
+        /// <returns>An int corresponding to the token</returns>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yylex" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yylex" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        public abstract int yylex();
+
+        /// <summary>
+        /// Traditional error reporting provided by LEX-like scanners
+        /// to their YACC-like clients.
+        /// </summary>
+        /// <param name="format">Message format string</param>
+        /// <param name="args">Optional array of args</param>
+        [SuppressMessage( "Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "yyerror" )]
+        [SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "yyerror" )]
+        // Reason for FxCop message suppression -
+        // This is a traditional name for YACC-like functionality
+        public virtual void yyerror( string format, params object[] args ) { }
+    }
+
+    /// <summary>
+    /// Encapsulated state for the parser.
+    /// Opaque to users, visible to the tool-generated code.
+    /// </summary>
+#if EXPORT_GPPG
+    public class State
+    {
+        /// <summary>
+        /// The number of states in the automaton.
+        /// </summary>
+        public int number;
+#else
+    internal class State {
+        /// <summary>
+        /// The index of this state in the states array.
+        /// </summary>
+        internal int number;
+#endif
+        internal Dictionary<int, int> ParserTable;   // Terminal -> ParseAction
+        internal Dictionary<int, int> Goto;          // NonTerminal -> State;
+        internal int defaultAction; // = 0;		     // ParseAction
+
+        /// <summary>
+        /// State transition data for this state. Pairs of elements of the 
+        /// goto array associate symbol ordinals with next state indices.
+        /// The actions array is passed to another constructor. 
+        /// </summary>
+        /// <param name="actions">The action list</param>c
+        /// <param name="goToList">Next state data</param>
+        public State( int[] actions, int[] goToList )
+            : this( actions ) {
+            Goto = new Dictionary<int, int>();
+            for (int i = 0; i < goToList.Length; i += 2)
+                Goto.Add( goToList[i], goToList[i + 1] );
+        }
+
+        /// <summary>
+        /// Action data for this state. Pairs of elements of the 
+        /// action array associate action ordinals with each of
+        /// those symbols that have actions in the current state.
+        /// </summary>
+        /// <param name="actions">The action array</param>
+        public State( int[] actions ) {
+            ParserTable = new Dictionary<int, int>();
+            for (int i = 0; i < actions.Length; i += 2)
+                ParserTable.Add( actions[i], actions[i + 1] );
+        }
+
+        /// <summary>
+        /// Set the default action for this state.
+        /// </summary>
+        /// <param name="defaultAction">Ordinal of the default action</param>
+        public State( int defaultAction ) {
+            this.defaultAction = defaultAction;
+        }
+
+        /// <summary>
+        /// Set the default action and the state transition table.
+        /// </summary>
+        /// <param name="defaultAction">The default action</param>
+        /// <param name="goToList">Transitions from this state</param>
+        public State( int defaultAction, int[] goToList )
+            : this( defaultAction ) {
+            Goto = new Dictionary<int, int>();
+            for (int i = 0; i < goToList.Length; i += 2)
+                Goto.Add( goToList[i], goToList[i + 1] );
+        }
+    }
+
+    /// <summary>
+    /// Rule representation at runtime.
+    /// </summary>
+#if EXPORT_GPPG
+    public class Rule
+#else
+    internal class Rule
+#endif
+ {
+        internal int LeftHandSide; // symbol
+        internal int[] RightHandSide; // symbols
+
+        /// <summary>
+        /// Rule constructor.  This holds the ordinal of
+        /// the left hand side symbol, and the list of
+        /// right hand side symbols, in lexical order.
+        /// </summary>
+        /// <param name="left">The LHS non-terminal</param>
+        /// <param name="right">The RHS symbols, in lexical order</param>
+        public Rule( int left, int[] right ) {
+            this.LeftHandSide = left;
+            this.RightHandSide = right;
+        }
+    }
+
+    /// <summary>
+    /// Stack utility for the shift-reduce parser.
+    /// GPPG parsers have three instances:
+    /// (1) The parser state stack, T = QUT.Gppg.State,
+    /// (2) The semantic value stack, T = TValue,
+    /// (3) The location stack, T = TSpan.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+#if EXPORT_GPPG
+    public class PushdownPrefixState<T>
+#else
+    internal class PushdownPrefixState<T>
+#endif
+ {
+        //  Note that we cannot use the BCL Stack<T> class
+        //  here as derived types need to index into stacks.
+        //
+        private T[] array = new T[8];
+        private int tos = 0;
+
+        /// <summary>
+        /// Indexer for values of the stack below the top.
+        /// </summary>
+        /// <param name="index">index of the element, starting from the bottom</param>
+        /// <returns>the selected element</returns>
+        public T this[int index] { get { return array[index]; } }
+
+        /// <summary>
+        /// The current depth of the stack.
+        /// </summary>
+        public int Depth { get { return tos; } }
+
+        internal void Push( T value ) {
+            if (tos >= array.Length) {
+                T[] newarray = new T[array.Length * 2];
+                System.Array.Copy( array, newarray, tos );
+                array = newarray;
+            }
+            array[tos++] = value;
+        }
+
+        internal T Pop() {
+            T rslt = array[--tos];
+            array[tos] = default( T );
+            return rslt;
+        }
+
+        internal T TopElement() { return array[tos - 1]; }
+
+        internal bool IsEmpty() { return tos == 0; }
+    }
+}
+

src/DataStreamSuite/Bts.ColumnSortExpressions/Usings.cs

@@ -0,0 +1,4 @@
+global using System;
+global using System.Linq;
+global using System.Collections.Generic;
+global using System.Collections.Immutable;

src/DataStreamSuite/Bts.DataStream.Websocket/Bts.DataStream.Websocket.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\client\spark_websocket\spark_websocket.csproj" />
+    <ProjectReference Include="..\DataStreamExpressions\DataStreamExpressions.csproj" />
+    <ProjectReference Include="..\..\client\spark_core\spark_core.csproj" />
+  </ItemGroup>
+
+</Project>

src/DataStreamSuite/Bts.DataStream.Websocket/ClientSubscription.cs

@@ -0,0 +1,9 @@
+namespace Bts.DataStream.Websocket;
+
+class ClientSubscription(WebsocketClientID id, SubscriptionParams @params, IDisposable dispose) : IDisposable {
+   public SubscriptionParams Params => @params;
+   public WebsocketClientID Id => id;
+
+   public void Dispose() =>
+      dispose.Dispose();
+}

src/DataStreamSuite/Bts.DataStream.Websocket/DataSync.cs

@@ -0,0 +1,301 @@
+namespace Bts.DataStream.Websocket;
+
+using BCG;
+
+using bts;
+using bts.api.core;
+using bts.collections;
+
+using Bts.DataStreamExpressions;
+using Bts.Websocket;
+
+using mbts.utils;
+
+using Spark.Core.Disposables;
+using Spark.Core.Json;
+
+using System.Buffers;
+using System.Reactive.Subjects;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Nodes;
+
+/// <summary>
+/// Represents an I/O model (<see cref="ISubject{TSource, TResult}"/>), that accepts websocket
+/// requests (from clients) as input, and emits data/notifications (to clients) as output.
+/// This class's chief role is managing data subscriptions to sparkd on the clients' behalf.
+/// </summary>
+public class DataSync(JsonSerializerOptions? serializerOpts = null) :
+   ISubject<WebsocketConnectionUpdate, IEnumerable<WebsocketOutgoingMessage>> {
+   protected readonly object lockObj = new();
+   readonly JsonSerializerOptions serializerOpts = serializerOpts ?? JsonSerializerOptions.Default;
+   readonly Dictionary<WebsocketClientID, List<ClientSubscription>> clients = [];
+
+   event Action<IEnumerable<WebsocketOutgoingMessage>>? requestSend;
+
+   public void OnCompleted() =>
+      Log.Api.info("DataSync incoming request stream has completed.");
+
+   public void OnError(Exception error) =>
+      Log.Api.error($"DataSync error: {error}");
+
+   public void OnNext(WebsocketConnectionUpdate value) {
+      switch (value.Type) {
+         case WebsocketConnectionUpdateType.IncomingMessage:
+            onIncomingMessage(value.IncomingMessage);
+            break;
+         case WebsocketConnectionUpdateType.Connect:
+            onConnect(value.Connect);
+            break;
+         case WebsocketConnectionUpdateType.Disconnect:
+            onDisconnect(value.Disconnect);
+            break;
+         default:
+            Log.assert(false, $"Unexpected WebsocketConnectionUpdate type: {value.Type}");
+            break;
+      }
+   }
+
+   public IDisposable Subscribe(IObserver<IEnumerable<WebsocketOutgoingMessage>> observer) {
+      lock (lockObj) {
+         requestSend += observer.OnNext;
+         return Disposable.Create(Dispose);
+      }
+      void Dispose() {
+         lock (lockObj) {
+            requestSend -= observer.OnNext;
+         }
+      }
+   }
+
+   static JsonRpcId? extractRpcId(string messageBody) {
+      try {
+         return JsonNode.Parse(messageBody)
+            ?.AsObject()
+            ?.GetValueOrDefault("id")
+            ?.Deserialize<JsonRpcId>();
+      } catch {
+         return null;
+      }
+   }
+
+   static string getRpcNotification(DataPacket dp) {
+      using (var buffer = new MemoryStream())
+      using (var writer = new Utf8JsonWriter(buffer))
+      using (writer.WriteObject()) {
+         writer.WriteString("method", "subscription");
+         using (writer.WriteObject("params")) {
+            writer.Write("tableName", dp.schema.tableName);
+            writer.Write("columns", dp.schema.columnInfo);
+            var cellJsonFactories = dp.schema.columnInfo.Select(getCellJsonFactory).ToList();
+            using (writer.WriteArray("added")) {
+               foreach (IBlueRow row in (dp.addedRows?.Cast<IBlueRow>()).empty_if_null()) {
+                  using (writer.WriteObject()) {
+                     for (int i = 0; i < cellJsonFactories.Count; i++) {
+                        writer.Write(dp.schema.columnInfo[i].colName, cellJsonFactories[i](row));
+                     }
+                  }
+               }
+            }
+            using (writer.WriteArray("deleted")) {
+               foreach (IBlueRow row in (dp.deletedRows?.Cast<IBlueRow>()).empty_if_null()) {
+                  using (writer.WriteObject()) {
+                     for (int i = 0; i < cellJsonFactories.Count; i++) {
+                        writer.Write(dp.schema.columnInfo[i].colName, cellJsonFactories[i](row));
+                     }
+                  }
+               }
+            }
+         }
+         writer.WriteString("jsonrpc", "2.0");
+         writer.Flush();
+         return Encoding.UTF8.GetString(buffer.ToArray());
+      }
+   }
+
+   static Func<IBlueRow, JsonNode?> getCellJsonFactory(ColumnInfo colInfo) {
+      var t = colInfo.colType;
+      if (t == typeof(int)) {
+         return NullCheckWrapper(v => (int)v);
+      }
+      if (t == typeof(uint)) {
+         return NullCheckWrapper(v => (uint)v);
+      }
+      if (t == typeof(long)) {
+         return NullCheckWrapper(v => (long)v);
+      }
+      if (t == typeof(ulong)) {
+         return NullCheckWrapper(v => (ulong)v);
+      }
+      if (t == typeof(short)) {
+         return NullCheckWrapper(v => (short)v);
+      }
+      if (t == typeof(ushort)) {
+         return NullCheckWrapper(v => (ushort)v);
+      }
+      if (t == typeof(double)) {
+         return NullCheckWrapper(v => (double)v);
+      }
+      if (t == typeof(float)) {
+         return NullCheckWrapper(v => (float)v);
+      }
+      if (t == typeof(bool)) {
+         return NullCheckWrapper(v => (bool)v);
+      }
+      return NullCheckWrapper(v => (string)v);
+
+      Func<IBlueRow, JsonNode?> NullCheckWrapper(Func<object, JsonNode> toJson) =>
+         r => {
+            var obj = r[colInfo.colNo];
+            if (obj is null) {
+               return null;
+            }
+            return toJson(obj);
+         };
+   }
+
+   void onConnect(WebsocketConnectNotification notification) {
+      var id = notification.Id;
+      lock (lockObj) {
+         clients.Add(id, []);
+      }
+      Log.Api.info($"DataStreamWebsocketDataSync client connected. clientId: {notification.Id}");
+      if (notification.Message is not null) {
+         onIncomingMessage(notification.Message);
+      }
+   }
+
+   void onDisconnect(WebsocketDisconnectNotification notification) {
+      Log.Api.warn($"DataStreamWebsocketDataSync client disconnected. clientId: {notification.Id}");
+      unsubscribeAll(notification.Id);
+      clients.Remove(notification.Id);
+   }
+
+   void onIncomingMessage(WebsocketIncomingMessage message) {
+      var id = message.sender_client_id;
+      if (!JsonRpcRequest.TryDeserialize(message, out var req, out var err)) {
+         onBadRequest(message, err);
+         return;
+      }
+      switch (req.Method!.ToLower()) {
+         case "subscribe":
+            subscribe(id, req);
+            break;
+         case "publish":
+            Log.Api.error("DataStreamWebsocket api 'publish' not implemented.");
+            // TODO
+            break;
+         case "unsubscribe":
+            unsubscribe(id, req);
+            break;
+         case "unsubscribe_all":
+            unsubscribeAll(id);
+            break;
+         default:
+            Log.Api.error($"Received request of unknown type: {req}");
+            break;
+      }
+   }
+
+   void sendResponse<T>(WebsocketClientID id, JsonRpcId rpcId, T rpcParams) {
+      var rpcRes = JsonRpcResponse.Create(rpcId, rpcParams);
+      var rpcResStr = JsonSerializer.Serialize(rpcRes, serializerOpts);
+      send([new(id, rpcResStr)]);
+   }
+
+   void sendError<T>(WebsocketClientID id, JsonRpcId rpcId, JsonRpcError<T> error) {
+      var rpcRes = JsonRpcResponse.CreateError(rpcId, error);
+      var rpcResStr = JsonSerializer.Serialize(rpcRes, serializerOpts);
+      send([new(id, rpcResStr)]);
+   }
+
+   bool send(IEnumerable<WebsocketOutgoingMessage> messages) {
+      lock (lockObj) {
+         if (requestSend is null) {
+            Log.Api.warn(
+               $"Unable to send message(s) because '{nameof(requestSend)}' handler is null");
+            return false;
+         }
+         requestSend(messages);
+         return true;
+      }
+   }
+
+   void subscribe(WebsocketClientID id, JsonRpcRequest<JsonObject?> req) {
+      var subParams = req.Params!.Deserialize<SubscriptionParams>()!;
+      var exp = DataStreamExpressionsInterpreter.Evaluate(subParams.Query!);
+      var stream = exp.getView(new Dictionary<string, StatementExpression>(0));
+      var sub = new ClientSubscription(id, subParams, Disposable.Create(Dispose));
+      lock (lockObj) {
+         clients[id].Add(sub);
+         sendResponse(id, req.Id!.Value, req.Params);
+         stream.onChange += OnChange;
+      }
+
+      void OnChange(object? newValue) {
+         var dp = ExceptionAssert.of_type<DataPacket>(newValue);
+         var notif = getRpcNotification(dp);
+         send([new(id, notif)]);
+      }
+
+      void Dispose() =>
+         stream.onChange -= OnChange;
+   }
+
+   void unsubscribe(WebsocketClientID id, JsonRpcRequest<JsonObject?> req) {
+      var subParams = req.Params!.Deserialize<SubscriptionParams>();
+      var subParamsStr = JsonSerializer.Serialize(subParams, serializerOpts);
+      // Minimize amount of code inside lock (just need it to find/remove the subscription)
+      List<ClientSubscription>? subs = null;
+      ClientSubscription? sub = null;
+      lock (lockObj) {
+         subs = clients.GetValueOrDefault(id);
+         subs?.TryRemoveFirst(s => s!.Params.Equals(subParams), out sub);
+      }
+      if (subs is null) {
+         // Didn't find client (log/throw).
+         var msg = $"Unable to unsubscribe: did not find client. Id: {id}.\nParams:\n{subParamsStr}";
+         Log.Api.error(msg);
+         throw new Exception(msg);
+      }
+      if (sub is null) {
+         // Found client, but didn't find subscription (log/throw).
+         var msg = $"Unable to unsubscribe: did not find the specified subscription. " +
+            $"Id: {id}. Request:\n{subParams}";
+         Log.Api.error(msg);
+         throw new Exception(msg);
+      }
+      // Found client and subscription (dispose/remove subscription).
+      Log.Api.info($"Unsubscribing client. Id: {id}.\nParams:\n{subParamsStr}");
+      sub.Dispose();
+   }
+
+   void unsubscribeAll(WebsocketClientID id) {
+      lock (lockObj) {
+         if (!clients.TryGetValue(id, out var subs)) {
+            throw new Exception(
+               $"Unable to unsubscribe: did not find client with id {id}");
+         }
+         subs.DisposeAll();
+         subs.Clear();
+      }
+   }
+
+   void onBadRequest(WebsocketIncomingMessage req, string? errorMsg) {
+      var rpcId = extractRpcId(req.message_body);
+      var logMsg = $"Recieved invalid request:\n{req.message_body}";
+      if (errorMsg is not null) {
+         logMsg += $"\n\n**Exception**\n{errorMsg}";
+      }
+      Log.Api.error(logMsg);
+      if (rpcId is null) {
+         return;
+      }
+      // Send error back to client
+      var rpcErr = JsonRpcError.Create(
+         (long)JsonRpcErrorCode.InvalidRequest,
+         $"Received invalid request: {errorMsg ?? "unknown error"}",
+         req.message_body);
+      sendError(req.sender_client_id, rpcId.Value, rpcErr);
+   }
+}

src/DataStreamSuite/Bts.DataStream.Websocket/JObjectExtensions.cs

@@ -0,0 +1,34 @@
+namespace Bts.DataStream.Websocket;
+
+using Newtonsoft.Json.Linq;
+
+using System.Diagnostics.CodeAnalysis;
+
+public static class JObjectExtensions {
+   public static bool TryParse<T>(
+      this JObject filter, string key, [MaybeNull] out T obj, [NotNullWhen(false)] out string? error) {
+      obj = default;
+      var value = filter.GetValueOrDefault(key)?.ToString();
+      if (value == null) {
+         error = $"{key} not present";
+         return true;
+      }
+      return WebsocketJsonParsers.TryParse(value, key, out obj, out error);
+   }
+
+   public static bool TryParse<T>(
+     this JObject filter, string key, out T result, [NotNullWhen(false)] out string? error, T defaultValue) {
+      var value = filter.GetValueOrDefault(key)?.ToString();
+      if (value == null) {
+         result = defaultValue;
+         error = $"{key} not present";
+         return true;
+      }
+      if (WebsocketJsonParsers.TryParse<T>(value, key, out var maybeRes, out error)) {
+         result = maybeRes ?? defaultValue;
+         return true;
+      }
+      result = defaultValue;
+      return false;
+   }
+}

src/DataStreamSuite/Bts.DataStream.Websocket/JsonParseResult.cs

@@ -0,0 +1,24 @@
+namespace Bts.DataStream.Websocket;
+
+using Newtonsoft.Json.Linq;
+
+class JsonParseResult {
+   public string? MessageId { get; init; }
+   public RequestType Type { get; init; }
+   public JObject? Parameters { get; init; }
+   public string? Error { get; init; }
+   public bool Successful => Error is not null;
+
+   public static JsonParseResult CreateError(string error) =>
+      new() {
+         Error = error,
+         MessageId = "missing"
+      };
+
+   public static JsonParseResult Create(string messageId, RequestType type, JObject parameters) =>
+      new() {
+         MessageId = messageId,
+         Parameters = parameters,
+         Type = type
+      };
+}

src/DataStreamSuite/Bts.DataStream.Websocket/JsonRpcErrorCode.cs

@@ -0,0 +1,6 @@
+namespace Bts.DataStream.Websocket;
+
+public enum JsonRpcErrorCode {
+   None = 0,
+   InvalidRequest = 1,
+}

src/DataStreamSuite/Bts.DataStream.Websocket/MultilineStringJsonConverter.cs

@@ -0,0 +1,48 @@
+namespace Bts.DataStream.Websocket;
+
+using Spark.Core;
+
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+class MultilineStringJsonConverter : JsonConverter<string> {
+   public override string? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) {
+      if (typeToConvert != typeof(string)) {
+         throw new ArgumentException($"Unable to parse {typeToConvert}", nameof(typeToConvert));
+      }
+      return reader.TokenType switch {
+         JsonTokenType.String => StringImpl(ref reader),
+         JsonTokenType.StartArray => ArrayImpl(ref reader),
+         _ => throw new ArgumentException(
+            $"Unable to parse {typeof(SubscriptionParams)} from {reader.TokenType}"),
+      };
+
+      static string? StringImpl(ref Utf8JsonReader reader) =>
+         new(reader.GetString()!);
+
+      static string? ArrayImpl(ref Utf8JsonReader reader) {
+         var lines = new List<string>(2);
+         while (reader.Read()) {
+            switch (reader.TokenType) {
+               case JsonTokenType.String:
+                  lines.Add(reader.GetString()!);
+                  break;
+               case JsonTokenType.EndArray:
+                  return string.Join("\n", lines);
+            }
+         }
+         throw new JsonException(
+            $"Failed to parse {typeof(SubscriptionParams)} (did not reach end of array)");
+      }
+   }
+
+   public override void Write(Utf8JsonWriter writer, string value, JsonSerializerOptions options) {
+      var lines = value.Split("\n");
+      if (lines.Length < 2) {
+         writer.WriteRawValue(value);
+         return;
+      }
+      writer.WriteRawValue($"[{", ".join(lines)}]");
+   }
+}

src/DataStreamSuite/Bts.DataStream.Websocket/RequestType.cs

@@ -0,0 +1,8 @@
+namespace Bts.DataStream.Websocket;
+
+public enum RequestType {
+   Unspecified,
+   Subscribe,
+   Unsubscribe,
+   UnsubscribeAll,
+}

src/DataStreamSuite/Bts.DataStream.Websocket/Session.cs

@@ -0,0 +1,27 @@
+namespace Bts.DataStream.Websocket;
+
+using bts;
+
+using Bts.Websocket;
+
+using Google.Protobuf;
+
+using System.Text.Json;
+
+public static class Session {
+   static int sessionIdCounter;
+
+   public static async Task Start(
+      WebsocketServerConfig config, JsonSerializerOptions? opts) {
+      opts ??= JsonSerializerOptions.Default;
+      var sessionId = Interlocked.Increment(ref sessionIdCounter);
+      var gateway = new WebsocketGatewayObservable(config);
+      var sync = new DataSync(opts);
+      using (gateway.Subscribe(sync))
+      using (sync.Subscribe(gateway)) {
+         Log.Api.info($"Starting DataStream Websocket Session {sessionId}");
+         Log.Api.info($"DataStream Websocket Session {sessionId} config:\n{JsonFormatter.Default.Format(config)}");
+         await gateway.ConnectAsync();
+      }
+   }
+}

src/DataStreamSuite/Bts.DataStream.Websocket/SubscriptionParams.cs

@@ -0,0 +1,110 @@
+namespace Bts.DataStream.Websocket;
+
+using Spark.Core;
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+public class SubscriptionParams : IEquatable<SubscriptionParams> {
+   static class PropNames {
+      public const string QUERY = "query";
+   }
+
+   public SubscriptionParams(string? query) {
+      Query = query;
+   }
+
+   // Serializer supports plain string, or an array of lines for convenience
+   [MaybeNull]
+   [JsonPropertyName(PropNames.QUERY)]
+   [JsonConverter(typeof(MultilineStringJsonConverter))]
+   public string? Query { get; set; }
+
+   public bool Equals(SubscriptionParams? other) =>
+      other is not null &&
+      Query == other.Query;
+
+   class SubscriptionParamsConverter : JsonConverter<SubscriptionParams> {
+      public override bool CanConvert(Type typeToConvert) =>
+         typeToConvert == typeof(SubscriptionParams);
+
+      public override SubscriptionParams Read(
+         ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) {
+         if (typeToConvert != typeof(SubscriptionParams)) {
+            throw new ArgumentException($"Unable to parse {typeToConvert}", nameof(typeToConvert));
+         }
+         return read(ref reader);
+      }
+
+      SubscriptionParams read(ref Utf8JsonReader reader) {
+         return reader.TokenType switch {
+            JsonTokenType.String => stringImpl(ref reader),
+            JsonTokenType.StartArray => arrayImpl(ref reader),
+            JsonTokenType.StartObject => objectImpl(ref reader),
+            _ => throw new ArgumentException(
+               $"Unable to parse {typeof(SubscriptionParams)} from {reader.TokenType}"),
+         };
+
+         static SubscriptionParams stringImpl(ref Utf8JsonReader reader) =>
+            new(reader.GetString()!);
+
+         static SubscriptionParams arrayImpl(ref Utf8JsonReader reader) {
+            var lines = new List<string>(2);
+            while (reader.Read()) {
+               switch (reader.TokenType) {
+                  case JsonTokenType.String:
+                     lines.Add(reader.GetString()!);
+                     break;
+                  case JsonTokenType.EndArray:
+                     return new("\n".join(lines));
+               }
+            }
+            throw new JsonException(
+               $"Failed to parse {typeof(SubscriptionParams)} (did not reach end of array)");
+         }
+
+         static SubscriptionParams objectImpl(ref Utf8JsonReader reader) {
+            var lines = new List<string>(2);
+            while (reader.Read()) {
+               switch (reader.TokenType) {
+                  case JsonTokenType.PropertyName:
+                     var propName = reader.GetString()!;
+                     if (propName == PropNames.QUERY) {
+                        switch (reader.TokenType) {
+                           case JsonTokenType.StartArray:
+                              return arrayImpl(ref reader);
+                           case JsonTokenType.String:
+                              return stringImpl(ref reader);
+                        }
+                     }
+                     break;
+                  case JsonTokenType.String:
+                     lines.Add(reader.GetString()!);
+                     break;
+                  case JsonTokenType.EndArray:
+                     return new("\n".join(lines));
+               }
+            }
+            throw new JsonException(
+               $"Failed to parse {typeof(SubscriptionParams)} (did not reach end of array)");
+         }
+      }
+
+      public override void Write(
+         Utf8JsonWriter writer, SubscriptionParams value, JsonSerializerOptions options) {
+         var q = value.Query;
+         var lines = q?.Split("\n");
+         if (lines is null || lines.Length < 2) {
+            writer.WriteString(PropNames.QUERY, value.Query);
+            return;
+         }
+         writer.WriteStartArray(PropNames.QUERY);
+         foreach (var l in lines) {
+            writer.WriteStringValue(l);
+         }
+         writer.WriteEndArray();
+      }
+   }
+}

src/DataStreamSuite/Bts.DataStream.Websocket/Usings.cs

@@ -0,0 +1,5 @@
+global using bts.websocket_core;
+
+global using System;
+
+global using System.Collections.Immutable;

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Bts.DataStream.WebsocketClient.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net7.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <EnableDefaultContentItems>True</EnableDefaultContentItems>
+  </PropertyGroup>
+
+</Project>

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Error.cshtml

@@ -0,0 +1,26 @@
+@page
+@model ErrorModel
+@{
+    ViewData["Title"] = "Error";
+}
+
+<h1 class="text-danger">Error.</h1>
+<h2 class="text-danger">An error occurred while processing your request.</h2>
+
+@if (Model.ShowRequestId)
+{
+    <p>
+        <strong>Request ID:</strong> <code>@Model.RequestId</code>
+    </p>
+}
+
+<h3>Development Mode</h3>
+<p>
+    Swapping to the <strong>Development</strong> environment displays detailed information about the error that occurred.
+</p>
+<p>
+    <strong>The Development environment shouldn't be enabled for deployed applications.</strong>
+    It can result in displaying sensitive information from exceptions to end users.
+    For local debugging, enable the <strong>Development</strong> environment by setting the <strong>ASPNETCORE_ENVIRONMENT</strong> environment variable to <strong>Development</strong>
+    and restarting the app.
+</p>

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Error.cshtml.cs

@@ -0,0 +1,27 @@
+using System.Diagnostics;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace Bts.DataStream.WebsocketClient.Pages;
+
+[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
+[IgnoreAntiforgeryToken]
+public class ErrorModel : PageModel
+{
+    public string? RequestId { get; set; }
+
+    public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
+
+    private readonly ILogger<ErrorModel> _logger;
+
+    public ErrorModel(ILogger<ErrorModel> logger)
+    {
+        _logger = logger;
+    }
+
+    public void OnGet()
+    {
+        RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier;
+    }
+}
+

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Index.cshtml

@@ -0,0 +1,15 @@
+@page
+@model IndexModel
+@{
+  ViewData["Title"] = "Home page";
+}
+
+<div class="text-center">
+  <h1 class="display-4">Welcome</h1>
+  <p>Learn about <a href="https://docs.microsoft.com/aspnet/core">building Web apps with ASP.NET Core</a>.</p>
+  <button id="connectButton">Connect to Websocket</button>
+  <div id="output"></div>
+  <input type="text" id="methodInput" placeholder="Enter method name" />
+  <input type="text" id="paramsInput" placeholder="Enter method parameters (if any)" />
+  <button id="sendMessageButton">Send JSON-RPC Request</button>
+</div>

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Index.cshtml.cs

@@ -0,0 +1,16 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace Bts.DataStream.WebsocketClient.Pages;
+
+public class IndexModel : PageModel {
+   private readonly ILogger<IndexModel> _logger;
+
+   public IndexModel(ILogger<IndexModel> logger) {
+      _logger = logger;
+   }
+
+   public void OnGet() {
+
+   }
+}

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Privacy.cshtml

@@ -0,0 +1,8 @@
+@page
+@model PrivacyModel
+@{
+    ViewData["Title"] = "Privacy Policy";
+}
+<h1>@ViewData["Title"]</h1>
+
+<p>Use this page to detail your site's privacy policy.</p>

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Privacy.cshtml.cs

@@ -0,0 +1,19 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace Bts.DataStream.WebsocketClient.Pages;
+
+public class PrivacyModel : PageModel
+{
+    private readonly ILogger<PrivacyModel> _logger;
+
+    public PrivacyModel(ILogger<PrivacyModel> logger)
+    {
+        _logger = logger;
+    }
+
+    public void OnGet()
+    {
+    }
+}
+

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Shared/_Layout.cshtml

@@ -0,0 +1,51 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>@ViewData["Title"] - Bts.DataStream.WebsocketClient</title>
+    <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.min.css" />
+    <link rel="stylesheet" href="~/css/site.css" asp-append-version="true" />
+    <link rel="stylesheet" href="~/Bts.DataStream.WebsocketClient.styles.css" asp-append-version="true" />
+</head>
+<body>
+    <header>
+        <nav class="navbar navbar-expand-sm navbar-toggleable-sm navbar-light bg-white border-bottom box-shadow mb-3">
+            <div class="container">
+                <a class="navbar-brand" asp-area="" asp-page="/Index">Bts.DataStream.WebsocketClient</a>
+                <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target=".navbar-collapse" aria-controls="navbarSupportedContent"
+                        aria-expanded="false" aria-label="Toggle navigation">
+                    <span class="navbar-toggler-icon"></span>
+                </button>
+                <div class="navbar-collapse collapse d-sm-inline-flex justify-content-between">
+                    <ul class="navbar-nav flex-grow-1">
+                        <li class="nav-item">
+                            <a class="nav-link text-dark" asp-area="" asp-page="/Index">Home</a>
+                        </li>
+                        <li class="nav-item">
+                            <a class="nav-link text-dark" asp-area="" asp-page="/Privacy">Privacy</a>
+                        </li>
+                    </ul>
+                </div>
+            </div>
+        </nav>
+    </header>
+    <div class="container">
+        <main role="main" class="pb-3">
+            @RenderBody()
+        </main>
+    </div>
+
+    <footer class="border-top footer text-muted">
+        <div class="container">
+            &copy; 2023 - Bts.DataStream.WebsocketClient - <a asp-area="" asp-page="/Privacy">Privacy</a>
+        </div>
+    </footer>
+
+    <script src="~/lib/jquery/dist/jquery.min.js"></script>
+    <script src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js"></script>
+    <script src="~/js/site.js" asp-append-version="true"></script>
+
+    @await RenderSectionAsync("Scripts", required: false)
+</body>
+</html>

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Shared/_Layout.cshtml.css

@@ -0,0 +1,48 @@
+/* Please see documentation at https://docs.microsoft.com/aspnet/core/client-side/bundling-and-minification
+for details on configuring this project to bundle and minify static web assets. */
+
+a.navbar-brand {
+  white-space: normal;
+  text-align: center;
+  word-break: break-all;
+}
+
+a {
+  color: #0077cc;
+}
+
+.btn-primary {
+  color: #fff;
+  background-color: #1b6ec2;
+  border-color: #1861ac;
+}
+
+.nav-pills .nav-link.active, .nav-pills .show > .nav-link {
+  color: #fff;
+  background-color: #1b6ec2;
+  border-color: #1861ac;
+}
+
+.border-top {
+  border-top: 1px solid #e5e5e5;
+}
+.border-bottom {
+  border-bottom: 1px solid #e5e5e5;
+}
+
+.box-shadow {
+  box-shadow: 0 .25rem .75rem rgba(0, 0, 0, .05);
+}
+
+button.accept-policy {
+  font-size: 1rem;
+  line-height: inherit;
+}
+
+.footer {
+  position: absolute;
+  bottom: 0;
+  width: 100%;
+  white-space: nowrap;
+  line-height: 60px;
+}

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/Shared/_ValidationScriptsPartial.cshtml

@@ -0,0 +1,2 @@
+<script src="~/lib/jquery-validation/dist/jquery.validate.min.js"></script>
+<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.min.js"></script>

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/_ViewImports.cshtml

@@ -0,0 +1,3 @@
+@using Bts.DataStream.WebsocketClient
+@namespace Bts.DataStream.WebsocketClient.Pages
+@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Pages/_ViewStart.cshtml

@@ -0,0 +1,3 @@
+@{
+    Layout = "_Layout";
+}

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Program.cs

@@ -0,0 +1,26 @@
+using Microsoft.AspNetCore.Mvc;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Add services to the container.
+builder.Services.AddRazorPages();
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline.
+if (!app.Environment.IsDevelopment()) {
+   app.UseExceptionHandler("/Error");
+   // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
+   app.UseHsts();
+}
+
+app.UseHttpsRedirection();
+app.UseStaticFiles();
+
+app.UseRouting();
+
+app.UseAuthorization();
+
+app.MapRazorPages();
+
+app.Run();

src/DataStreamSuite/Bts.DataStream.WebsocketClient/Properties/launchSettings.json

@@ -0,0 +1,37 @@
+{
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:29312",
+      "sslPort": 44390
+    }
+  },
+  "profiles": {
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "http://localhost:5214",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "https://localhost:7176;http://localhost:5214",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

src/DataStreamSuite/Bts.DataStream.WebsocketClient/appsettings.Development.json

@@ -0,0 +1,9 @@
+{
+  "DetailedErrors": true,
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

src/DataStreamSuite/Bts.DataStream.WebsocketClient/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}

src/DataStreamSuite/Bts.DataStream.WebsocketClient/wwwroot/css/site.css

@@ -0,0 +1,22 @@
+html {
+  font-size: 14px;
+}
+
+@media (min-width: 768px) {
+  html {
+    font-size: 16px;
+  }
+}
+
+.btn:focus, .btn:active:focus, .btn-link.nav-link:focus, .form-control:focus, .form-check-input:focus {
+  box-shadow: 0 0 0 0.1rem white, 0 0 0 0.25rem #258cfb;
+}
+
+html {
+  position: relative;
+  min-height: 100%;
+}
+
+body {
+  margin-bottom: 60px;
+}

src/DataStreamSuite/Bts.DataStream.WebsocketClient/wwwroot/js/site.js

@@ -0,0 +1,67 @@
+// Please see documentation at https://docs.microsoft.com/aspnet/core/client-side/bundling-and-minification
+// for details on configuring this project to bundle and minify static web assets.
+
+// Write your JavaScript code.
+const connectButton = document.getElementById('connectButton');
+const output = document.getElementById('output');
+const methodInput = document.getElementById('methodInput');
+const paramsInput = document.getElementById('paramsInput');
+const sendMessageButton = document.getElementById('sendMessageButton');
+
+let socket;
+
+connectButton.addEventListener('click', () => {
+    if (socket && socket.readyState === WebSocket.OPEN) {
+        return;
+    }
+
+    socket = new WebSocket('ws://localhost:8080'); // Replace with your WebSocket server URL
+
+    socket.onopen = (event) => {
+        output.innerHTML += 'Connected to WebSocket server<br>';
+    };
+
+    socket.onmessage = (event) => {
+        const message = JSON.parse(event.data);
+        output.innerHTML += `Received JSON-RPC response: ${JSON.stringify(message)}<br>`;
+    };
+
+    socket.onclose = (event) => {
+        if (event.wasClean) {
+            output.innerHTML += `Connection closed cleanly, code=${event.code}, reason=${event.reason}<br>`;
+        } else {
+            output.innerHTML += 'Connection abruptly closed<br>';
+        }
+    };
+
+    socket.onerror = (error) => {
+        output.innerHTML += `WebSocket Error: ${error.message}<br>`;
+    };
+});
+
+sendMessageButton.addEventListener('click', () => {
+    // const method = methodInput.value;
+    // const params = paramsInput.value;
+    const method = 'subscribe';
+    const params = `{
+"expression": "literal("n", "2.0")"
+}'
+`
+    if (socket && socket.readyState === WebSocket.OPEN && method) {
+        // const reqParams = {
+        //   'expression': message
+        // }
+        const request = {
+            jsonrpc: '2.0',
+            method: method,
+            params: {
+              query: `literal("n", "2.0")`
+            },
+            id: 1, // You can set a unique ID for each request
+        };
+
+        socket.send(JSON.stringify(request));
+        methodInput.value = ''; // Clear the input fields
+        paramsInput.value = '';
+    }
+});

src/DataStreamSuite/Bts.DataStream.WebsocketServer/Bts.DataStream.WebsocketServer.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net7.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Bts.DataStream.Websocket\Bts.DataStream.Websocket.csproj" />
+  </ItemGroup>
+
+</Project>

src/DataStreamSuite/Bts.DataStream.WebsocketServer/DataStreamWebsocketServer.conf

@@ -0,0 +1,7 @@
+{
+  "host": "localhost",
+  "port": 8080,
+  "scheme": "ws",
+  "default_end_point": "/",
+  "keep_alive_interval_secs": 1
+}

src/DataStreamSuite/Bts.DataStream.WebsocketServer/Program.cs

@@ -0,0 +1,76 @@
+using bts.api.core;
+
+using Bts.DataStream.Websocket;
+
+using Google.Protobuf;
+
+using System.CommandLine.Parsing;
+using System.Text.Json;
+
+static WebsocketServerConfig readConfigFile(string path) {
+   using var fs = File.OpenRead(path);
+   using var sr = new StreamReader(fs);
+   return JsonParser.Default.Parse<WebsocketServerConfig>(sr);
+}
+
+static WebsocketServerConfig? readConfigArg(ArgumentResult result) {
+   var path = result.Tokens.Select(t => t.Value).FirstOrDefault() ?? string.Empty;
+   return readConfigFile(path);
+}
+
+static WebsocketServerConfig getDefaultConfig() {
+   const string defaultCfgPath = "DataStreamWebsocketServer.conf";
+   if (File.Exists(defaultCfgPath)) {
+      return readConfigFile(defaultCfgPath);
+   }
+   return new() {
+      Scheme = "http",
+      Host = "localhost",
+      Port = 8080,
+      DefaultEndPoint = "/",
+      KeepAliveIntervalSecs = 1
+   };
+}
+   
+static async Task run(
+   WebsocketServerConfig? wssConfig, string user, string password, string? sparkdConfigSource) {
+   var opts = new JsonSerializerOptions(JsonSerializerDefaults.Web);
+   wssConfig ??= getDefaultConfig();
+   Console.WriteLine("Starting DataStreamWebsocketServer...");
+   var serviceCtx = ServiceContext.create(sparkdConfigSource);
+   await serviceCtx.login(user, password);
+   await Session.Start(wssConfig, opts);
+   // if (sparkdConfigSource is not null && sparkdConfigSource.Length > 9999) {
+   // } else {
+   //    await ChatGptSession.Start();
+   // }
+}
+
+var userOpt = new Option<string>("--user", () => "bts");
+var passOpt = new Option<string>("--password", () => string.Empty);
+var sparkdConfigSourceOpt = new Option<string>(
+   "--sparkd", description: "The sparkd config server url");
+// var bling = new ParseArgument<WebsocketServerConfig?>(parseWsConfig);
+
+// WebsocketServerConfig? parseWsConfig(ArgumentResult result) {
+//    Token t;
+//    TokenType tt;
+//    Symbol s;
+//    throw new NotImplementedException();
+// }
+
+var configOpt = new Option<WebsocketServerConfig?>(
+   "--config", readConfigArg, description: "WebsocketServerConfig file path");
+configOpt.SetDefaultValue(new());
+var rootCommand = new RootCommand("Starts a DataStream Websocket Server");
+rootCommand.AddOption(configOpt);
+rootCommand.AddOption(userOpt);
+rootCommand.AddOption(passOpt);
+rootCommand.SetHandler(run, configOpt, userOpt, passOpt, sparkdConfigSourceOpt);
+
+try {
+   return await rootCommand.InvokeAsync(args);
+} catch (Exception ex) {
+   Console.WriteLine($"Error: {ex}");
+}
+return 1;

src/DataStreamSuite/Bts.DataStream.WebsocketServer/Usings.cs

@@ -0,0 +1,7 @@
+global using Bts.Websocket;
+
+global using bts.websocket_core;
+
+global using System.CommandLine;
+
+global using System.Collections.Immutable;

src/DataStreamSuite/Bts.DataStreamWebApp.Client/.eslintrc.cjs

@@ -0,0 +1,20 @@
+module.exports = {
+  root: true,
+  env: { browser: true, es2020: true },
+  extends: [
+    'eslint:recommended',
+    'plugin:react/recommended',
+    'plugin:react/jsx-runtime',
+    'plugin:react-hooks/recommended',
+  ],
+  ignorePatterns: ['dist', '.eslintrc.cjs'],
+  parserOptions: { ecmaVersion: 'latest', sourceType: 'module' },
+  settings: { react: { version: '18.2' } },
+  plugins: ['react-refresh'],
+  rules: {
+    'react-refresh/only-export-components': [
+      'warn',
+      { allowConstantExport: true },
+    ],
+  },
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Client/.gitignore

@@ -0,0 +1,24 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?

src/DataStreamSuite/Bts.DataStreamWebApp.Client/Bts.DataStreamWebApp.Client.esproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.VisualStudio.JavaScript.Sdk/0.5.128-alpha">
+  <PropertyGroup>
+    <StartupCommand>npm run dev</StartupCommand>
+    <JavaScriptTestRoot>src\</JavaScriptTestRoot>
+    <JavaScriptTestFramework>Jest</JavaScriptTestFramework>
+    <!-- Allows the build (or compile) script located on package.json to run on Build -->
+    <ShouldRunBuildScript>false</ShouldRunBuildScript>
+    <!-- Folder where production build objects will be placed -->
+    <PublishAssetsDirectory>$(MSBuildProjectDirectory)\dist</PublishAssetsDirectory>
+  </PropertyGroup>
+</Project>

src/DataStreamSuite/Bts.DataStreamWebApp.Client/README.md

@@ -0,0 +1,8 @@
+# React + Vite
+
+This template provides a minimal setup to get React working in Vite with HMR and some ESLint rules.
+
+Currently, two official plugins are available:
+
+- [@vitejs/plugin-react](https://github.com/vitejs/vite-plugin-react/blob/main/packages/plugin-react/README.md) uses [Babel](https://babeljs.io/) for Fast Refresh
+- [@vitejs/plugin-react-swc](https://github.com/vitejs/vite-plugin-react-swc) uses [SWC](https://swc.rs/) for Fast Refresh

src/DataStreamSuite/Bts.DataStreamWebApp.Client/index.html

@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <link rel="icon" type="image/svg+xml" href="/vite.svg" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Vite + React</title>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="/src/main.jsx"></script>
+  </body>
+</html>

src/DataStreamSuite/Bts.DataStreamWebApp.Client/nuget.config

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <clear />
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
+  </packageSources>
+  <disabledPackageSources>
+    <clear />
+  </disabledPackageSources>
+</configuration>

src/DataStreamSuite/Bts.DataStreamWebApp.Client/package.json

@@ -0,0 +1,27 @@
+{
+  "name": "bts.datastreamwebapp.client",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "lint": "eslint . --ext js,jsx --report-unused-disable-directives --max-warnings 0",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0",
+    "react-use-websocket": "^4.5.0"
+  },
+  "devDependencies": {
+    "@types/react": "^18.2.43",
+    "@types/react-dom": "^18.2.17",
+    "@vitejs/plugin-react": "^4.2.1",
+    "eslint": "^8.55.0",
+    "eslint-plugin-react": "^7.33.2",
+    "eslint-plugin-react-hooks": "^4.6.0",
+    "eslint-plugin-react-refresh": "^0.4.5",
+    "vite": "^5.0.8"
+  }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Client/public/vite.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--logos" width="31.88" height="32" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 257"><defs><linearGradient id="IconifyId1813088fe1fbc01fb466" x1="-.828%" x2="57.636%" y1="7.652%" y2="78.411%"><stop offset="0%" stop-color="#41D1FF"></stop><stop offset="100%" stop-color="#BD34FE"></stop></linearGradient><linearGradient id="IconifyId1813088fe1fbc01fb467" x1="43.376%" x2="50.316%" y1="2.242%" y2="89.03%"><stop offset="0%" stop-color="#FFEA83"></stop><stop offset="8.333%" stop-color="#FFDD35"></stop><stop offset="100%" stop-color="#FFA800"></stop></linearGradient></defs><path fill="url(#IconifyId1813088fe1fbc01fb466)" d="M255.153 37.938L134.897 252.976c-2.483 4.44-8.862 4.466-11.382.048L.875 37.958c-2.746-4.814 1.371-10.646 6.827-9.67l120.385 21.517a6.537 6.537 0 0 0 2.322-.004l117.867-21.483c5.438-.991 9.574 4.796 6.877 9.62Z"></path><path fill="url(#IconifyId1813088fe1fbc01fb467)" d="M185.432.063L96.44 17.501a3.268 3.268 0 0 0-2.634 3.014l-5.474 92.456a3.268 3.268 0 0 0 3.997 3.378l24.777-5.718c2.318-.535 4.413 1.507 3.936 3.838l-7.361 36.047c-.495 2.426 1.782 4.5 4.151 3.78l15.304-4.649c2.372-.72 4.652 1.36 4.15 3.788l-11.698 56.621c-.732 3.542 3.979 5.473 5.943 2.437l1.313-2.028l72.516-144.72c1.215-2.423-.88-5.186-3.54-4.672l-25.505 4.922c-2.396.462-4.435-1.77-3.759-4.114l16.646-57.705c.677-2.35-1.37-4.583-3.769-4.113Z"></path></svg>

src/DataStreamSuite/Bts.DataStreamWebApp.Client/src/App.css

@@ -0,0 +1,44 @@
+#root {
+    max-width: 1280px;
+    margin: 0 auto;
+    padding: 2rem;
+    text-align: center;
+    --cell-background-color: #293136;
+    --cell-color: #cbe3ef;
+}
+
+tr:nth-child(even) {
+    background: #F2F2F2;
+}
+
+tr:nth-child(odd) {
+    background: #FFF;
+}
+
+th, td {
+    padding-left: 1rem;
+    padding-right: 1rem;
+    background-color: var(--cell-background-color);
+    color: var(--cell-color);
+}
+
+textarea#query-input {
+  height: 5em;
+  width: 50em;
+}
+
+button#query-button {
+  height: 5em;
+  vertical-align: top;
+}
+
+table#query-output {
+  float: none;
+  clear: both;
+}
+
+p#footer {
+  float: none;
+  clear: both;
+  vertical-align: bottom;
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Client/src/App.jsx

@@ -0,0 +1,88 @@
+import { Component } from "react";
+import "./App.css";
+
+export class Home extends Component {
+  static displayName = Home.name;
+  static sparkdHost = "localhost";
+
+  render() {
+    let socket = null;
+    const wsUrl = `ws://localhost:5268/ws`;
+
+    function connectToSparkd() {
+      if (socket == null) {
+        socket = new WebSocket(wsUrl);
+      }
+      if (socket && socket.readyState === WebSocket.OPEN) {
+        return;
+      }
+
+      const output = document.getElementById("query-output");
+      socket.onopen = (event) => {
+        console.log(`Connected to ${wsUrl}`);
+      };
+
+      socket.onmessage = (event) => {
+        console.log(`Received message: ${event.data}`);
+        output.innerHTML = event.data;
+      };
+
+      socket.onerror = (error) => {
+        console.log(`Error on websocket ${wsUrl}: ${error}`);
+      };
+
+      socket.onclose = (event) => {
+        if (event.wasClean) {
+          const msg = `Connection to ${wsUrl} closed cleanly, code=${event.code}, reason=${event.reason}`;
+          console.log(msg);
+        } else {
+          const msg = `Connection to ${wsUrl} abruptly closed`;
+          console.log(msg);
+        }
+      };
+    }
+
+    function executeQuery() {
+      if (socket == null || !socket) {
+        connectToSparkd();
+      }
+      if (socket == null || !socket) {
+        console.log("Failed to connect to websocket server");
+        return;
+      }
+      if (socket.readyState === WebSocket.OPEN) {
+        const queryInput = document.getElementById("query-input");
+        const rpcReq = {
+          jsonrpc: "2.0",
+          method: "subscribe",
+          params: {
+            query: queryInput.value,
+          },
+          id: 1,
+        };
+        socket.send(JSON.stringify(rpcReq));
+      }
+    }
+
+    return (
+      <div>
+        <h1>Data Stream Query Analyzer</h1>
+        <p>Run queries against the BTS Cloud</p>
+        <div>
+          <textarea id="query-input" placeholder="Enter Query"></textarea>
+          <button id="query-button" onClick={executeQuery}>
+            Execute
+          </button>
+        </div>
+        <table id="query-output"></table>
+        <p id="footer">
+          The <code>ClientApp</code> subdirectory is a standard React
+          application based on the <code>create-react-app</code> template. If
+          you open a command prompt in that directory, you can run{" "}
+          <code>npm</code> commands such as <code>npm test</code> or{" "}
+          <code>npm install</code>.
+        </p>
+      </div>
+    );
+  }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Client/src/assets/react.svg

@@ -0,0 +1 @@
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src/DataStreamSuite/Bts.DataStreamWebApp.Client/src/index.css

@@ -0,0 +1,68 @@
+:root {
+  font-family: Inter, system-ui, Avenir, Helvetica, Arial, sans-serif;
+  line-height: 1.5;
+  font-weight: 400;
+
+  color-scheme: light dark;
+  color: rgba(255, 255, 255, 0.87);
+  background-color: #242424;
+
+  font-synthesis: none;
+  text-rendering: optimizeLegibility;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+a {
+  font-weight: 500;
+  color: #646cff;
+  text-decoration: inherit;
+}
+a:hover {
+  color: #535bf2;
+}
+
+body {
+  margin: 0;
+  display: flex;
+  place-items: center;
+  min-width: 320px;
+  min-height: 100vh;
+}
+
+h1 {
+  font-size: 3.2em;
+  line-height: 1.1;
+}
+
+button {
+  border-radius: 8px;
+  border: 1px solid transparent;
+  padding: 0.6em 1.2em;
+  font-size: 1em;
+  font-weight: 500;
+  font-family: inherit;
+  background-color: #1a1a1a;
+  cursor: pointer;
+  transition: border-color 0.25s;
+}
+button:hover {
+  border-color: #646cff;
+}
+button:focus,
+button:focus-visible {
+  outline: 4px auto -webkit-focus-ring-color;
+}
+
+@media (prefers-color-scheme: light) {
+  :root {
+    color: #213547;
+    background-color: #ffffff;
+  }
+  a:hover {
+    color: #747bff;
+  }
+  button {
+    background-color: #f9f9f9;
+  }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Client/src/main.jsx

@@ -0,0 +1,10 @@
+import React from 'react'
+import ReactDOM from 'react-dom/client'
+import {Home} from './App.jsx'
+import './index.css'
+
+ReactDOM.createRoot(document.getElementById('root')).render(
+  <React.StrictMode>
+    <Home />
+  </React.StrictMode>,
+)

src/DataStreamSuite/Bts.DataStreamWebApp.Client/vite.config.js

@@ -0,0 +1,60 @@
+import { fileURLToPath, URL } from 'node:url';
+
+import { defineConfig } from 'vite';
+import plugin from '@vitejs/plugin-react';
+import fs from 'fs';
+import path from 'path';
+import child_process from 'child_process';
+
+const baseFolder =
+    process.env.APPDATA !== undefined && process.env.APPDATA !== ''
+        ? `${process.env.APPDATA}/ASP.NET/https`
+        : `${process.env.HOME}/.aspnet/https`;
+
+const certificateArg = process.argv.map(arg => arg.match(/--name=(?<value>.+)/i)).filter(Boolean)[0];
+const certificateName = certificateArg ? certificateArg.groups.value : "bts.datastreamwebapp.client";
+
+if (!certificateName) {
+    console.error('Invalid certificate name. Run this script in the context of an npm/yarn script or pass --name=<<app>> explicitly.')
+    process.exit(-1);
+}
+
+const certFilePath = path.join(baseFolder, `${certificateName}.pem`);
+const keyFilePath = path.join(baseFolder, `${certificateName}.key`);
+
+if (!fs.existsSync(certFilePath) || !fs.existsSync(keyFilePath)) {
+    if (0 !== child_process.spawnSync('dotnet', [
+        'dev-certs',
+        'https',
+        '--export-path',
+        certFilePath,
+        '--format',
+        'Pem',
+        '--no-password',
+    ], { stdio: 'inherit', }).status) {
+        throw new Error("Could not create certificate.");
+    }
+}
+
+// https://vitejs.dev/config/
+export default defineConfig({
+    plugins: [plugin()],
+    resolve: {
+        alias: {
+            '@': fileURLToPath(new URL('./src', import.meta.url))
+        }
+    },
+    server: {
+        proxy: {
+            '^/weatherforecast': {
+                target: 'https://localhost:7128/',
+                secure: false
+            }
+        },
+        port: 5173,
+        https: {
+            key: fs.readFileSync(keyFilePath),
+            cert: fs.readFileSync(certFilePath),
+        }
+    }
+})

src/DataStreamSuite/Bts.DataStreamWebApp.Server/Bts.DataStreamWebApp.Server.csproj

@@ -0,0 +1,35 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <InvariantGlobalization>true</InvariantGlobalization>
+    <SpaRoot>..\Bts.DataStreamWebApp.Client</SpaRoot>
+    <SpaProxyLaunchCommand>npm run dev</SpaProxyLaunchCommand>
+    <SpaProxyServerUrl>https://localhost:5173</SpaProxyServerUrl>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="CommandLineParser" Version="2.9.1" />
+    <PackageReference Include="Microsoft.AspNetCore.SpaProxy">
+      <Version>8.*-*</Version>
+    </PackageReference>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.4.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Bts.DataStreamWebApp.Client\Bts.DataStreamWebApp.Client.esproj">
+      <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
+    </ProjectReference>
+    <ProjectReference Include="..\DataStream\DataStream.csproj" />
+    <ProjectReference Include="..\SharedStreams\SharedStreams.csproj" />
+    <ProjectReference Include="..\..\client\spark_api\spark_api.csproj" />
+    <ProjectReference Include="..\..\client\spark_websocket\spark_websocket.csproj" />
+  </ItemGroup>
+
+  <!-- <ItemGroup>
+    <Content Update="wwwroot\alt-index.html" CopyToPublishDirectory="Never" />
+  </ItemGroup> -->
+</Project>

src/DataStreamSuite/Bts.DataStreamWebApp.Server/Bts.DataStreamWebApp.Server.http

@@ -0,0 +1,6 @@
+@Bts.DataStreamWebApp.Server_HostAddress = http://localhost:5268
+
+GET {{Bts.DataStreamWebApp.Server_HostAddress}}/weatherforecast/
+Accept: application/json
+
+###

src/DataStreamSuite/Bts.DataStreamWebApp.Server/Controllers/DataStreamSubscriptionController.cs

@@ -0,0 +1,106 @@
+namespace Bts.DataStreamWebApp.Server.Controllers;
+
+using BCG;
+
+using bts.api.core;
+
+using Bts.DataStreamExpressions;
+using Bts.Websocket;
+
+using Microsoft.AspNetCore.Mvc;
+
+using Spark.Core.Disposables;
+
+using System.Net.WebSockets;
+using System.Text;
+using System.Text.Json;
+
+[Route("/ws")]
+public class DataStreamSubscriptionController(ILogger<DataStreamSubscriptionController> logger) : ControllerBase {
+   readonly ILogger<DataStreamSubscriptionController> _logger = logger;
+   IDisposable? streamSubscription;
+
+   [Route("/ws")]
+   public async Task Get() {
+      if (!HttpContext.WebSockets.IsWebSocketRequest) {
+         _logger.LogError("Expected websocket request on path '{}'", HttpContext.Request.Path);
+         return;
+      }
+      Console.WriteLine("Establishing websocket connection...");
+      using var webSocket = await HttpContext.WebSockets.AcceptWebSocketAsync();
+      Console.WriteLine($"Websocket connection established.");
+      await runWebSocketServer(null, "bts", string.Empty, webSocket);
+   }
+
+   public static async Task Echo(WebSocket webSocket) {
+      var buffer = new byte[1024 * 4];
+      var receiveResult = await webSocket.ReceiveAsync(
+          new ArraySegment<byte>(buffer), CancellationToken.None);
+
+      while (!receiveResult.CloseStatus.HasValue) {
+         await webSocket.SendAsync(
+             new ArraySegment<byte>(buffer, 0, receiveResult.Count),
+             receiveResult.MessageType,
+             receiveResult.EndOfMessage,
+             CancellationToken.None);
+
+         receiveResult = await webSocket.ReceiveAsync(
+             new ArraySegment<byte>(buffer), CancellationToken.None);
+      }
+
+      await webSocket.CloseAsync(
+          receiveResult.CloseStatus.Value,
+          receiveResult.CloseStatusDescription,
+          CancellationToken.None);
+   }
+
+   async Task<int> runWebSocketServer(string? sparkd, string user, string password, WebSocket webSocket) {
+      var context = ServiceContext.create(sparkd);
+      await context.login(user, password);
+      var buffer = new byte[1024 * 4];
+      var receiveResult = await webSocket.ReceiveAsync(
+          new ArraySegment<byte>(buffer), CancellationToken.None);
+
+      try {
+         while (!receiveResult.CloseStatus.HasValue) {
+            receiveResult = await webSocket.ReceiveAsync(
+                new ArraySegment<byte>(buffer), CancellationToken.None);
+            var msg = Encoding.UTF8.GetString(buffer, 0, receiveResult.Count);
+            var rpcReq = JsonSerializer.Deserialize<JsonRpcRequest<DataStreamSubscription>>(msg);
+            var queryArgs = rpcReq!.Params;
+            var exp = DataStreamExpressionsInterpreter.Evaluate(queryArgs.Query!);
+            if (exp is null) {
+               Console.WriteLine($"Invalid query expression: {queryArgs.Query}.");
+               continue;
+            }
+            var vs = exp.getView(new Dictionary<string, StatementExpression>(0));
+            Disposable.dispose(ref streamSubscription);
+            vs.onChange += onStreamChanged;
+            streamSubscription = Disposable.Create(() => vs.onChange -= onStreamChanged);
+         }
+      } catch (Exception ex) {
+         Console.WriteLine($"Exception on WebsocketServer thread: {ex}");
+         return 1;
+      }
+
+      return 0;
+
+      async void onStreamChanged(object newValue) {
+         if (newValue is not DataPacket dp) {
+            Console.WriteLine(
+               $"OnStreamChanged delegate expected DataPacket (actually received {newValue?.GetType()}.");
+            return;
+         }
+         Console.WriteLine("Received stream update.");
+         var added_rows_str = dp.addedRows.get_printed_rows(val => val.Length);
+         var msg = $"Received new rows:\n{added_rows_str}";
+         var encoded = Encoding.UTF8.GetBytes(msg);
+         var payload = new ArraySegment<byte>(encoded, 0, encoded.Length);
+         await webSocket.SendAsync(
+             payload,
+             receiveResult.MessageType,
+             receiveResult.EndOfMessage,
+             CancellationToken.None);
+      }
+   }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/Controllers/WeatherForecastController.cs

@@ -0,0 +1,22 @@
+namespace Bts.DataStreamWebApp.Server.Controllers;
+using Microsoft.AspNetCore.Mvc;
+
+[ApiController]
+[Route("[controller]")]
+public class WeatherForecastController(ILogger<WeatherForecastController> logger) : ControllerBase {
+   static readonly string[] Summaries = [
+      "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
+   ];
+
+   readonly ILogger<WeatherForecastController> _logger = logger;
+
+   [HttpGet(Name = "GetWeatherForecast")]
+   public IEnumerable<WeatherForecast> Get() {
+      return Enumerable.Range(1, 5).Select(index => new WeatherForecast {
+         Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
+         TemperatureC = Random.Shared.Next(-20, 55),
+         Summary = Summaries[Random.Shared.Next(Summaries.Length)]
+      })
+      .ToArray();
+   }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/DataStreamSubscription.cs

@@ -0,0 +1,8 @@
+namespace Bts.DataStreamWebApp.Server;
+
+using System.Text.Json.Serialization;
+
+public class DataStreamSubscription {
+   [JsonPropertyName("query")]
+   public string? Query { get; set; }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/DataStreamUpdate.cs

@@ -0,0 +1,8 @@
+namespace Bts.DataStreamWebApp.Server;
+
+using BCG;
+
+class DataStreamUpdate {
+   public List<IBlueRow> addedRows { get; set; } = new(0);
+   public List<IBlueRow> deletedRows { get; set; } = new(0);
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/DataStreamWebAppServerOptions.cs

@@ -0,0 +1,14 @@
+namespace Bts.DataStreamWebApp.Server;
+
+using CommandLine;
+
+class DataStreamWebAppServerOptions {
+   [Option("sparkd")]
+   public string? sparkd { get; set; }
+
+   [Option("user", Default = "bts")]
+   public string? user { get; set; }
+
+   [Option("password", Default = "")]
+   public string? password { get; set; }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/DataStreamWebsocketHandler.cs

@@ -0,0 +1,58 @@
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+
+using System;
+using System.Net.WebSockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Bts.DataStreamWebApp.Server {
+   // public class DataStreamWebSocketHandler {
+   //    readonly WebSocketConnectionManager _connectionManager = new();
+   //    readonly ILogger<DataStreamWebSocketHandler> _logger;
+
+   //    public DataStreamWebSocketHandler(
+   //       WebSocketConnectionManager connectionManager,
+   //       ILogger<DataStreamWebSocketHandler> logger
+   //    ) {
+   //       _connectionManager = connectionManager;
+   //       _logger = logger;
+   //    }
+
+   //    public async Task HandleWebSocket(HttpContext context, WebSocket webSocket) {
+   //       var socketId = _connectionManager.AddSocket(webSocket);
+
+   //       _logger.LogInformation($"WebSocket connection established with ID {socketId}");
+
+   //       while (webSocket.State == WebSocketState.Open) {
+   //          var message = await ReceiveMessageAsync(webSocket);
+   //          if (message != null) {
+   //             _logger.LogInformation($"Received message from ID {socketId}: {message}");
+   //             await BroadcastMessageAsync(message);
+   //          }
+   //       }
+
+   //       _connectionManager.RemoveSocket(socketId);
+   //       _logger.LogInformation($"WebSocket connection closed with ID {socketId}");
+   //    }
+
+   //    async Task<string?> ReceiveMessageAsync(WebSocket webSocket) {
+   //       var buffer = new byte[1024];
+   //       var result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
+
+   //       if (result.CloseStatus.HasValue) {
+   //          return null;
+   //       }
+
+   //       return System.Text.Encoding.UTF8.GetString(buffer, 0, result.Count);
+   //    }
+
+   //    async Task BroadcastMessageAsync(string message) {
+   //       foreach (var socket in _connectionManager.GetAllSockets()) {
+   //          if (socket.Value.State == WebSocketState.Open) {
+   //             await socket.Value.SendAsync(System.Text.Encoding.UTF8.GetBytes(message), WebSocketMessageType.Text, true, CancellationToken.None);
+   //          }
+   //       }
+   //    }
+   // }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/Program.cs

@@ -0,0 +1,158 @@
+using BCG;
+
+using bts;
+using bts.api.core;
+using bts.utils;
+
+using Bts.DataStreamExpressions;
+using Bts.DataStreamWebApp.Server;
+using Bts.DataStreamWebApp.Server.Controllers;
+
+using CommandLine;
+
+using mbts.config;
+
+using System.Net.WebSockets;
+using System.Reactive.Disposables;
+using System.Reactive.Linq;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+static string fmtReq(HttpRequest req) =>
+   $"{req.Protocol}://{req.Host}/{req.Path}?{req.QueryString}";
+
+static string fmtDataPacket(DataPacket dp) {
+   var sb = new StringBuilder();
+   var rows = dp.addedRows.Cast<IBlueRow>().ToList();
+   var colWidths = dp.schema.columnInfo.Select(c => rows.Max(r => r[c.colNo]?.ToString()?.Length ?? 0)).ToArray();
+   foreach (IBlueRow r in dp.addedRows) {
+      for (int i = 0; i < colWidths.Length; i++) {
+         var str = r[i]?.ToString() ?? string.Empty;
+         if (i > 0) {
+            sb.Append(" | ");
+         }
+         sb.Append(str);
+         var width = colWidths[i];
+         if (str.Length < width) {
+            sb.Append(new string(' ', width - str.Length));
+         }
+      }
+      sb.AppendLine();
+   }
+   return sb.ToString();
+}
+
+var parser = new Parser(ps => {
+   ps.CaseInsensitiveEnumValues = true;
+   ps.HelpWriter = Console.Out;
+});
+
+await parser.ParseArguments<DataStreamWebAppServerOptions>(args).
+   MapResult(run, errors => Task.FromResult(1));
+
+async Task<int> run(DataStreamWebAppServerOptions opts) {
+   BTSNativeMethods.provide_command_line(args, args.Length);
+   Configuration.initialize();
+   var context = ServiceContext.create(opts.sparkd);
+   await context.login(opts.user!, opts.password!);
+   var vsWorkLoop = Observable.Interval(TimeSpan.FromMilliseconds(200)).Subscribe(_ => {
+      ViewStreamDatabase.instance.doWork();
+      MasterWorker.getInstance(false).doWork();
+   });
+   var builder = WebApplication.CreateBuilder(args);
+   builder.Services.AddDirectoryBrowser();
+   var app = builder.Build();
+   var wsOpts = new WebSocketOptions {
+      KeepAliveInterval = TimeSpan.FromMinutes(2)
+   };
+   app.UseWebSockets(wsOpts);
+   app.UseDefaultFiles();
+   app.UseStaticFiles();
+   app.MapFallbackToFile("/index.html");
+
+   app.Use(async (context, next) => {
+      var reqDesc = fmtReq(context.Request);
+      Console.WriteLine($"Webserver received: {reqDesc}");
+      if (context.Request.Path == "/ws") {
+         if (context.WebSockets.IsWebSocketRequest) {
+            Console.WriteLine("Accepting websocket connection...");
+            using var webSocket = await context.WebSockets.AcceptWebSocketAsync();
+            Console.WriteLine("Websocket connection accepted.");
+            await runWebSocketServer(
+               opts.sparkd, opts.user!, opts.password!, webSocket);
+         } else {
+            context.Response.StatusCode = StatusCodes.Status400BadRequest;
+         }
+      } else {
+         Console.WriteLine($"Webserver ignoring req: {reqDesc}");
+         await next(context);
+      }
+   });
+
+   try {
+      await app.RunAsync();
+   } catch (Exception ex) {
+      Console.WriteLine($"Exception on DataStreamWebsocketServer thread: {ex}");
+      return 1;
+   }
+   Spark.Core.Disposables.Disposable.dispose(ref vsWorkLoop);
+   return 0;
+}
+
+async Task<int> runWebSocketServer(string? sparkd, string user, string password, WebSocket webSocket) {
+   var buffer = new byte[1024 * 4];
+   var receiveResult = await webSocket.ReceiveAsync(
+       new ArraySegment<byte>(buffer), CancellationToken.None);
+
+   try {
+      while (!receiveResult.CloseStatus.HasValue) {
+         Console.WriteLine("Awaiting websocket message from client");
+         receiveResult = await webSocket.ReceiveAsync(
+             new ArraySegment<byte>(buffer), CancellationToken.None);
+         var msg = Encoding.UTF8.GetString(buffer, 0, receiveResult.Count);
+         var rpcReq = JsonSerializer.Deserialize<Bts.Websocket.JsonRpcRequest<DataStreamSubscription>>(msg);
+         var queryArgs = rpcReq!.Params!;
+         // var queryArgs = new DataStreamSubscription { Query = msg };
+         var exp = DataStreamExpressionsInterpreter.Evaluate(queryArgs.Query!);
+         if (exp is null) {
+            Console.WriteLine($"Invalid query expression: {queryArgs.Query}.");
+            continue;
+         }
+         var vs = exp.getView(new Dictionary<string, StatementExpression>(0));
+         Console.WriteLine("Subscribing to stream...");
+         vs.onChange += onStreamChanged;
+
+         await webSocket.SendAsync(
+             new ArraySegment<byte>(buffer, 0, receiveResult.Count),
+             receiveResult.MessageType,
+             receiveResult.EndOfMessage,
+             CancellationToken.None);
+      }
+   } catch (Exception ex) {
+      Console.WriteLine($"Exception on WebsocketServer thread: {ex}");
+      return 1;
+   }
+
+   return 0;
+
+   async void onStreamChanged(object newValue) {
+      if (newValue is not DataPacket dp) {
+         Console.WriteLine(
+            $"OnStreamChanged delegate expected DataPacket (actually received {newValue?.GetType()}.");
+         return;
+      }
+      Console.WriteLine("Received stream update.");
+      var sb = new StringBuilder();
+      var updateDesc = fmtDataPacket(dp);
+      var msg = $"Received new rows:\n{updateDesc}";
+      // var payload = new ReadOnlyMemory<byte>([.. msg]);
+      var encoded = Encoding.UTF8.GetBytes(msg);
+      var payload = new ArraySegment<byte>(encoded, 0, encoded.Length);
+      await webSocket.SendAsync(
+          payload,
+          receiveResult.MessageType,
+          receiveResult.EndOfMessage,
+          CancellationToken.None);
+   }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/Properties/launchSettings.json

@@ -0,0 +1,48 @@
+{
+  "profiles": {
+    "default": {
+      "commandName": "Project",
+      "launchBrowser": true,
+      "applicationUrl": "http://localhost:5400"
+    },
+    "http": {
+      "commandName": "Project",
+      "launchBrowser": true,
+      "launchUrl": "swagger",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+        "ASPNETCORE_HOSTINGSTARTUPASSEMBLIES": "Microsoft.AspNetCore.SpaProxy"
+      },
+      "dotnetRunMessages": true,
+      "applicationUrl": "http://localhost:5268"
+    },
+    "https": {
+      "commandName": "Project",
+      "launchUrl": "swagger",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+        "ASPNETCORE_HOSTINGSTARTUPASSEMBLIES": "Microsoft.AspNetCore.SpaProxy"
+      },
+      "dotnetRunMessages": true,
+      "applicationUrl": "https://localhost:7128;http://localhost:5268"
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "launchUrl": "swagger",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+        "ASPNETCORE_HOSTINGSTARTUPASSEMBLIES": "Microsoft.AspNetCore.SpaProxy"
+      }
+    }
+  },
+  "$schema": "http://json.schemastore.org/launchsettings.json",
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:2083",
+      "sslPort": 44383
+    }
+  }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/WeatherForecast.cs

@@ -0,0 +1,12 @@
+namespace Bts.DataStreamWebApp.Server;
+
+public class WeatherForecast
+{
+   public DateOnly Date { get; set; }
+
+   public int TemperatureC { get; set; }
+
+   public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
+
+   public string? Summary { get; set; }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/WebsocketConnectionManager.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Concurrent;
+using System.Net.WebSockets;
+
+namespace Bts.DataStreamWebApp.Server {
+   // public class WebSocketConnectionManager {
+   //    private readonly ConcurrentDictionary<Guid, WebSocket> _sockets = new ConcurrentDictionary<Guid, WebSocket>();
+
+   //    public Guid AddSocket(WebSocket socket) {
+   //       var socketId = Guid.NewGuid();
+   //       _sockets.TryAdd(socketId, socket);
+   //       return socketId;
+   //    }
+
+   //    public WebSocket? GetSocket(Guid socketId) {
+   //       _sockets.TryGetValue(socketId, out var socket);
+   //       return socket;
+   //    }
+
+   //    public ConcurrentDictionary<Guid, WebSocket>.ValueCollection GetAllSockets() {
+   //       return _sockets.Values;
+   //    }
+
+   //    public Guid? GetSocketId(WebSocket socket) {
+   //       foreach (var (key, value) in _sockets) {
+   //          if (value == socket) {
+   //             return key;
+   //          }
+   //       }
+   //       return null;
+   //    }
+
+   //    public void RemoveSocket(Guid socketId) {
+   //       _sockets.TryRemove(socketId, out _);
+   //    }
+   // }
+}

src/DataStreamSuite/Bts.DataStreamWebApp.Server/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}