spark/src/DataStreamSuite/DataStream/Primitives/Join/JoinTableSchema.cs

using System;
using System.Collections;
using BCG.Utilities;

using bts;

namespace BCG
{
   /// <summary>
   /// Represents the schema of the Join Table. This schema is formed  by combining the respective
   /// schemas of the operands.
   /// </summary>
   public class JoinTableSchema : BlueTableSchema
   {
      private string myLeftJc = "", myRightJc = "", myLeftId = "", myRightId = "";
      private IDictionary myLeftNameToAlias = new Hashtable ();
      private IDictionary myRightNameToAlias = new Hashtable ();
      private IDictionary myAliasToLeftName = new Hashtable(),
                           myAliasToRightName = new Hashtable();
      /// <summary>
      /// Constructs the schema of the Jointable with the schema of the left and right tables. Incase of
      /// a name being there in both the shemas it prefixes the name with "L." or "R." accordingly. Column "id"
      /// is the last column in the schema
      /// </summary>
      /// <param name="leftSchema"></param>
      /// <param name="leftJc"></param>
      /// <param name="rightSchema"></param>
      /// <param name="rightJc"></param>
      public JoinTableSchema (IBlueTableSchema leftSchema, string leftJc, 
         IBlueTableSchema rightSchema, string rightJc)
      {
         myIndexByColOrder = new ColumnInfo[leftSchema.columnNames.Length + rightSchema.columnNames.Length + 1];
         myTableName = leftSchema.tableName + " J " + rightSchema.tableName;
         ColumnInfo[] cis = leftSchema.columnInfo;
         string assignedColName;
         bool renamed = false;
         foreach (ColumnInfo ci in cis)
         {
            assignedColName = ci.colName;
            while (rightSchema[assignedColName] != null)
            {
               assignedColName = "L." + assignedColName;
               renamed = true;
               while (leftSchema[assignedColName] != null)
                  assignedColName = "L." + assignedColName;
            }
            ColumnInfo newCi = new ColumnInfo (assignedColName, ci.colNo, ci.colType);
            Log.assert(myIndexByColName[newCi.colName] == null);
            Log.assert(myIndexByColOrder[newCi.colNo] == null);
            if (renamed)
               Log.assert(leftSchema[assignedColName] == null);
            Log.assert(rightSchema[assignedColName] == null);
            myIndexByColName [newCi.colName] = newCi;
            myIndexByColOrder [newCi.colNo] = newCi;
            myLeftNameToAlias[ci.colName] = newCi.colName;
            myLeftJc = ci.colName == leftJc ? assignedColName : myLeftJc;
            myLeftId = ci.colName == "id" ? assignedColName : myLeftId;
            renamed = false;
         }
         Log.assert(myLeftJc != "" && myLeftId != "");
         int n = leftSchema.columnNames.Length;
         cis = rightSchema.columnInfo;
         renamed = false;
         foreach (ColumnInfo ci in cis)
         {
            assignedColName = ci.colName;
            while (leftSchema[assignedColName] != null)
            {
               assignedColName = "R." + assignedColName;
               renamed = true;
               while(rightSchema[assignedColName] != null)
                  assignedColName = "R." + assignedColName;
            }
            ColumnInfo newCi = new ColumnInfo (assignedColName, ci.colNo + n, ci.colType);
            Log.assert(myIndexByColName[assignedColName] == null);
            Log.assert(myIndexByColOrder[newCi.colNo] == null);
            Log.assert(leftSchema[assignedColName] == null);
            if (renamed)
               Log.assert(rightSchema[assignedColName] == null);
            myIndexByColName [newCi.colName] = newCi;
            myIndexByColOrder [newCi.colNo] = newCi;
            myRightNameToAlias[ci.colName] = newCi.colName;
            myRightJc = ci.colName == rightJc ? assignedColName : myRightJc;
            myRightId = ci.colName == "id" ? assignedColName : myLeftJc;
            renamed = false;
         }
         myIndexByColName["id"] = new ColumnInfo("id", myIndexByColName.Count, typeof(int));
         myIndexByColOrder[myIndexByColOrder.Length - 1] = (ColumnInfo)myIndexByColName["id"];
         myAliasToLeftName = ProjectHelper.invertDic(myLeftNameToAlias);
         myAliasToRightName = ProjectHelper.invertDic(myRightNameToAlias);
      }

      public string leftJoinCol  {get{return myLeftJc;}}

      public string rightJoinCol {get{return myRightJc;}}

      public string getRenamedName (string origName, bool isLeft)
      {
         if (isLeft)
            return (string)myLeftNameToAlias[origName];
         return (string)myRightNameToAlias[origName];
      }

      public string getOriginalName(string rename, bool isLeft)
      {
         return isLeft ? myAliasToLeftName[rename].ToString() : myAliasToRightName[rename].ToString();
      }
   }
}