mcs/class/System.Data/Mono.Data.SqlExpressions/ColumnReference.cs

   1 //
   2 // ColumnReference.cs
   3 //
   4 // Author:
   5 //   Juraj Skripsky (juraj@hotfeet.ch)
   6 //
   7 // (C) 2004 HotFeet GmbH (http://www.hotfeet.ch)
   8 //
   9
  10 //
  11 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 using System;
  34 using System.Collections;
  35 using System.Data;
  36
  37 namespace Mono.Data.SqlExpressions {
  38         internal enum ReferencedTable {
  39                 Self,
  40                 Parent,
  41                 Child
  42         }
  43
  44         internal class ColumnReference : IExpression {
  45                 ReferencedTable refTable;
  46                 string relationName, columnName;
  47
  48                 public ColumnReference (string columnName) : this (ReferencedTable.Self, null, columnName) {}
  49
  50                 public ColumnReference (ReferencedTable refTable, string relationName, string columnName)
  51                 {
  52                         this.refTable = refTable;
  53                         this.relationName = relationName;
  54                         this.columnName = columnName;
  55                 }
  56
  57                 public ReferencedTable ReferencedTable {
  58                         get { return refTable; }
  59                 }
  60
  61                 protected DataRelation GetRelation (DataRow row)
  62                 {
  63                         DataRelationCollection relations;
  64                         if (relationName != null) {
  65                                 relations = row.Table.DataSet.Relations;
  66                                 return relations[relations.IndexOf(relationName)];
  67                         }
  68
  69                         if (refTable == ReferencedTable.Parent)
  70                                 relations = row.Table.ParentRelations;
  71                         else
  72                                 relations = row.Table.ChildRelations;
  73
  74                         if (relations.Count > 1)
  75                                 throw new EvaluateException (String.Format (
  76                                         "The table [{0}] is involved in more than one relation." +
  77                                         "You must explicitly mention a relation name.",
  78                                         row.Table.TableName));
  79                         else
  80                                 return relations[0];
  81                 }
  82
  83                 public DataRow GetReferencedRow (DataRow row)
  84                 {
  85                         switch (refTable) {
  86                         case ReferencedTable.Self:
  87                         default:
  88                                 return row;
  89
  90                         case ReferencedTable.Parent:
  91                                 return row.GetParentRow (GetRelation (row));
  92
  93                         case ReferencedTable.Child:
  94                                 return row.GetChildRows (GetRelation (row)) [0];
  95                         }
  96                 }
  97
  98                 public DataRow[] GetReferencedRows (DataRow row)
  99                 {
 100                         switch (refTable) {
 101                         case ReferencedTable.Self:
 102                         default:
 103                                 DataRow[] rows = new DataRow [row.Table.Rows.Count];
 104                                 row.Table.Rows.CopyTo (rows, 0);
 105                                 return rows;
 106
 107                         case ReferencedTable.Parent:
 108                                 return row.GetParentRows (GetRelation (row));
 109
 110                         case ReferencedTable.Child:
 111                                 return row.GetChildRows (GetRelation (row));
 112                         }
 113                 }
 114
 115                 public object[] GetValues (DataRow[] rows)
 116                 {
 117                         object[] values = new object [rows.Length];
 118                         for (int i = 0; i < rows.Length; i++)
 119                                 values [i] = Unify (rows [i][columnName]);
 120
 121                         return values;
 122                 }
 123
 124                 private object Unify (object val) {
 125                         if (Numeric.IsNumeric (val))
 126                                 return Numeric.Unify ((IConvertible)val);
 127
 128                         if (val == null || val == DBNull.Value)
 129                                 return null;
 130
 131                         if (val is bool || val is string || val is DateTime)
 132                                 return val;
 133
 134                         if (val is Enum)
 135                                 return (int)val;
 136
 137                         throw new EvaluateException (String.Format ("Cannot handle data type found in column '{0}'.", columnName));
 138                 }
 139
 140                 public object Eval (DataRow row)
 141                 {
 142                         DataRow referencedRow = GetReferencedRow (row);
 143                         if (referencedRow == null)
 144                                 return null;
 145
 146                         object val;
 147                         try {
 148                                 referencedRow._inExpressionEvaluation = true;
 149                                 val = referencedRow [columnName];
 150                                 referencedRow._inExpressionEvaluation = false;
 151                         } catch (IndexOutOfRangeException) {
 152                                 throw new EvaluateException (String.Format ("Cannot find column [{0}].", columnName));
 153                         }
 154                         return Unify (val);
 155                 }
 156         }
 157 }