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

   1 //
   2 // Functions.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 class IifFunction : UnaryExpression {
  39                 IExpression trueExpr, falseExpr;
  40                 public IifFunction (IExpression e, IExpression trueExpr, IExpression falseExpr) : base (e)
  41                 {
  42                         this.trueExpr = trueExpr;
  43                         this.falseExpr = falseExpr;
  44                 }
  45
  46                 override public object Eval (DataRow row)
  47                 {
  48                         bool val = (bool)expr.Eval (row);
  49                         return (val ? trueExpr.Eval (row) : falseExpr.Eval (row));
  50                 }
  51         }
  52
  53         internal class IsNullFunction : UnaryExpression {
  54                 IExpression defaultExpr;
  55                 public IsNullFunction (IExpression e, IExpression defaultExpr) : base (e)
  56                 {
  57                         this.defaultExpr = defaultExpr;
  58                 }
  59
  60                 override public object Eval (DataRow row)
  61                 {
  62                         object val = expr.Eval (row);
  63                         return (val != null ? val : defaultExpr.Eval (row));
  64                 }
  65         }
  66
  67         internal class ConvertFunction : UnaryExpression {
  68                 Type targetType;
  69                 public ConvertFunction (IExpression e, string targetType) : base (e)
  70                 {
  71                         try {
  72                                 this.targetType = Type.GetType (targetType, true);
  73                         } catch (TypeLoadException) {
  74                                 throw new EvaluateException (String.Format ("Invalid type name '{0}'.", targetType));
  75                         }
  76                 }
  77
  78                 override public object Eval (DataRow row)
  79                 {
  80                         object val = expr.Eval (row);
  81
  82                         if (val.GetType () == targetType)
  83                                 return val;
  84
  85                         //--> String is always allowed
  86                         if (targetType == typeof (string))
  87                                 return val.ToString();
  88
  89                         //only TimeSpan <--> String is allowed
  90                         if (targetType == typeof (TimeSpan)) {
  91                                 if (val is string)
  92                                         return TimeSpan.Parse ((string)val);
  93                                 else
  94                                         ThrowInvalidCastException (val);
  95                         }
  96
  97                         if (val is TimeSpan)
  98                                 ThrowInvalidCastException (val);
  99
 100                         //only Char <--> String/Int32/UInt32 is allowed
 101                         if (val is Char && !(targetType == typeof (Int32) || targetType == typeof (UInt32)))
 102                                 ThrowInvalidCastException (val);
 103
 104                         if (targetType == typeof (Char) && !(val is Int32 || val is UInt32))
 105                                 ThrowInvalidCastException (val);
 106
 107                         //bool <--> Char/Single/Double/Decimal/TimeSpan/DateTime is not allowed
 108                         if (val is Boolean && (targetType == typeof (Single) || targetType == typeof (Double) || targetType == typeof (Decimal)))
 109                                 ThrowInvalidCastException (val);
 110
 111                         if (targetType == typeof(Boolean) && (val is Single || val is Double || val is Decimal))
 112                                 ThrowInvalidCastException (val);
 113
 114                         //Convert throws the remaining invalid casts
 115                         return Convert.ChangeType (val, targetType);
 116
 117                 }
 118
 119                 private void ThrowInvalidCastException (object val) {
 120                         throw new InvalidCastException (String.Format ("Type '{0}' cannot be converted to '{1}'.", val.GetType(), targetType));
 121                 }
 122         }
 123 }