src/Boo.Lang/Runtime/CandidateMethod.cs

   1 #region license
   2 // Copyright (c) 2003, 2004, 2005 Rodrigo B. de Oliveira (rbo@acm.org)
   3 // All rights reserved.
   4 //
   5 // Redistribution and use in source and binary forms, with or without modification,
   6 // are permitted provided that the following conditions are met:
   7 //
   8 //     * Redistributions of source code must retain the above copyright notice,
   9 //     this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above copyright notice,
  11 //     this list of conditions and the following disclaimer in the documentation
  12 //     and/or other materials provided with the distribution.
  13 //     * Neither the name of Rodrigo B. de Oliveira nor the names of its
  14 //     contributors may be used to endorse or promote products derived from this
  15 //     software without specific prior written permission.
  16 //
  17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  18 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
  21 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  23 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  24 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  25 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27 #endregion
  28
  29
  30 using System;
  31 using System.Reflection;
  32
  33 namespace Boo.Lang.Runtime
  34 {
  35         public class CandidateMethod
  36         {
  37                 public const int ExactMatchScore = 7;
  38                 public const int UpCastScore = 6;
  39                 public const int WideningPromotion = 5;
  40                 public const int ImplicitConversionScore = 4;
  41                 public const int NarrowingPromotion = 3;
  42                 public const int DowncastScore = 2;
  43
  44                 public static int CalculateArgumentScore(Type paramType, Type argType)
  45                 {
  46                         if (null == argType)
  47                         {
  48                                 if (paramType.IsValueType) return -1;
  49                                 return CandidateMethod.ExactMatchScore;
  50                         }
  51                         else
  52                         {
  53                                 if (paramType == argType) return CandidateMethod.ExactMatchScore;
  54
  55                                 if (paramType.IsAssignableFrom(argType)) return CandidateMethod.UpCastScore;
  56
  57                                 if (argType.IsAssignableFrom(paramType)) return CandidateMethod.DowncastScore;
  58
  59                                 if (IsNumericPromotion(paramType, argType))
  60                                 {
  61                                         if (NumericTypes.IsWideningPromotion(paramType, argType)) return WideningPromotion;
  62                                         return CandidateMethod.NarrowingPromotion;
  63                                 }
  64
  65                                 MethodInfo conversion = RuntimeServices.FindImplicitConversionOperator(argType, paramType);
  66                                 if (null != conversion) return CandidateMethod.ImplicitConversionScore;
  67                         }
  68                         return -1;
  69                 }
  70
  71                 private readonly MethodInfo _method;
  72                 private readonly int[] _argumentScores;
  73                 private readonly bool _varArgs;
  74
  75                 public CandidateMethod(MethodInfo method, int argumentCount, bool varArgs)
  76                 {
  77                         _method = method;
  78                         _argumentScores = new int[argumentCount];
  79                         _varArgs = varArgs;
  80                 }
  81
  82                 public MethodInfo Method
  83                 {
  84                         get { return _method;  }
  85                 }
  86
  87                 public int[] ArgumentScores
  88                 {
  89                         get { return _argumentScores;  }
  90                 }
  91
  92                 public bool VarArgs
  93                 {
  94                         get { return _varArgs;  }
  95                 }
  96
  97                 public int MinimumArgumentCount
  98                 {
  99                         get { return _varArgs ? Parameters.Length - 1 : Parameters.Length; }
 100                 }
 101
 102                 public ParameterInfo[] Parameters
 103                 {
 104                         get { return _method.GetParameters();  }
 105                 }
 106
 107                 public Type VarArgsParameterType
 108                 {
 109                         get { return GetParameterType(Parameters.Length-1).GetElementType(); }
 110                 }
 111
 112                 public bool DoesNotRequireConversions
 113                 {
 114                         get { return !Array.Exists(_argumentScores, RequiresConversion); }
 115                 }
 116
 117                 private static bool RequiresConversion(int score)
 118                 {
 119                         return score < WideningPromotion;
 120                 }
 121
 122                 public Type GetParameterType(int i)
 123                 {
 124                         return Parameters[i].ParameterType;
 125                 }
 126
 127                 public static bool IsNumericPromotion(Type paramType, Type argType)
 128                 {
 129                         return RuntimeServices.IsPromotableNumeric(Type.GetTypeCode(paramType))
 130                                && RuntimeServices.IsPromotableNumeric(Type.GetTypeCode(argType));
 131                 }
 132         }
 133 }