/Dependencies/boo/src/Boo.Lang/Runtime/MethodResolver.cs
C# | 260 lines | 199 code | 34 blank | 27 comment | 46 complexity | d7dd92f9f210d6c88689e8574d825181 MD5 | raw file
Possible License(s): GPL-2.0
- #region license
- // Copyright (c) 2003, 2004, 2005 Rodrigo B. de Oliveira (rbo@acm.org)
- // All rights reserved.
- //
- // Redistribution and use in source and binary forms, with or without modification,
- // are permitted provided that the following conditions are met:
- //
- // * Redistributions of source code must retain the above copyright notice,
- // this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above copyright notice,
- // this list of conditions and the following disclaimer in the documentation
- // and/or other materials provided with the distribution.
- // * Neither the name of Rodrigo B. de Oliveira nor the names of its
- // contributors may be used to endorse or promote products derived from this
- // software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
- // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- #endregion
- using System;
- using System.Collections.Generic;
- using System.Reflection;
- namespace Boo.Lang.Runtime
- {
- public class MethodResolver
- {
- public static Type[] GetArgumentTypes(object[] arguments)
- {
- if (arguments.Length == 0) return DispatcherKey.NoArguments;
- Type[] types = new Type[arguments.Length];
- for (int i = 0; i < types.Length; ++i)
- {
- types[i] = GetObjectTypeOrNull(arguments[i]);
- }
- return types;
- }
- private static Type GetObjectTypeOrNull(object arg)
- {
- if (null == arg) return null;
- return arg.GetType();
- }
- private readonly Type[] _arguments;
- public MethodResolver(params Type[] argumentTypes)
- {
- _arguments = argumentTypes;
- }
- public CandidateMethod ResolveMethod(IEnumerable<MethodInfo> candidates)
- {
- List<CandidateMethod> applicable = FindApplicableMethods(candidates);
- if (applicable.Count == 0) return null;
- if (applicable.Count == 1) return applicable[0];
-
- List<CandidateMethod> dataPreserving = applicable.FindAll(DoesNotRequireConversions);
- if (dataPreserving.Count > 0) return BestMethod(dataPreserving);
- return BestMethod(applicable);
- }
- private static bool DoesNotRequireConversions(CandidateMethod candidate)
- {
- return candidate.DoesNotRequireConversions;
- }
- private CandidateMethod BestMethod(List<CandidateMethod> applicable)
- {
- applicable.Sort(BetterCandidate);
- return applicable[applicable.Count - 1];
- }
- private static int TotalScore(CandidateMethod c1)
- {
- int total = 0;
- foreach (int score in c1.ArgumentScores)
- {
- total += score;
- }
- return total;
- }
- private int BetterCandidate(CandidateMethod c1, CandidateMethod c2)
- {
- int result = Math.Sign(TotalScore(c1) - TotalScore(c2));
- if (result != 0) return result;
- if (c1.VarArgs && !c2.VarArgs) return -1;
- if (c2.VarArgs && !c1.VarArgs) return 1;
- int minArgumentCount = Math.Min(c1.MinimumArgumentCount, c2.MinimumArgumentCount);
- for (int i = 0; i < minArgumentCount; ++i)
- {
- result += MoreSpecificType(c1.GetParameterType(i), c2.GetParameterType(i));
- }
- if (result != 0) return result;
- if (c1.VarArgs && c2.VarArgs)
- {
- return MoreSpecificType(c1.VarArgsParameterType, c2.VarArgsParameterType);
- }
- return 0;
- }
- private static int MoreSpecificType(Type t1, Type t2)
- {
- // The less-generic type is more specific
- int result = GetTypeGenerity(t2) - GetTypeGenerity(t1);
- if (result != 0) return result;
- // If both types have the same generity, the deeper-nested type is more specific
- return GetLogicalTypeDepth(t1) - GetLogicalTypeDepth(t2);
- }
- private static int GetTypeGenerity(Type type)
- {
- if (!type.ContainsGenericParameters) return 0;
- return type.GetGenericArguments().Length;
- }
- private static int GetLogicalTypeDepth(Type type)
- {
- int depth = GetTypeDepth(type);
- return (type.IsValueType) ? depth - 1 : depth;
- }
- private static int GetTypeDepth(Type type)
- {
- if (type.IsByRef)
- {
- return GetTypeDepth(type.GetElementType());
- }
- else if (type.IsInterface)
- {
- return GetInterfaceDepth(type);
- }
- return GetClassDepth(type);
- }
- private static int GetClassDepth(Type type)
- {
- int depth = 0;
- Type objectType = typeof(object);
- while (type != objectType)
- {
- type = type.BaseType;
- ++depth;
- }
- return depth;
- }
- private static int GetInterfaceDepth(Type type)
- {
- Type[] interfaces = type.GetInterfaces();
- if (interfaces.Length > 0)
- {
- int current = 0;
- foreach (Type i in interfaces)
- {
- int depth = GetInterfaceDepth(i);
- if (depth > current) current = depth;
- }
- return 1+current;
- }
- return 1;
- }
- private List<CandidateMethod> FindApplicableMethods(IEnumerable<MethodInfo> candidates)
- {
- List<CandidateMethod> applicable = new List<CandidateMethod>();
- foreach (MethodInfo method in candidates)
- {
- CandidateMethod candidateMethod = IsApplicableMethod(method);
- if (null == candidateMethod) continue;
- applicable.Add(candidateMethod);
- }
- return applicable;
- }
- private CandidateMethod IsApplicableMethod(MethodInfo method)
- {
- ParameterInfo[] parameters = method.GetParameters();
- bool varargs = IsVarArgs(parameters);
- if (!ValidArgumentCount(parameters, varargs)) return null;
- CandidateMethod candidateMethod = new CandidateMethod(method, _arguments.Length, varargs);
- if (CalculateCandidateScore(candidateMethod)) return candidateMethod;
- return null;
- }
- private bool ValidArgumentCount(ParameterInfo[] parameters, bool varargs)
- {
- if (varargs)
- {
- int minArgumentCount = parameters.Length - 1;
- return _arguments.Length >= minArgumentCount;
- }
- return _arguments.Length == parameters.Length;
- }
- private bool IsVarArgs(ParameterInfo[] parameters)
- {
- if (parameters.Length == 0) return false;
- return HasParamArrayAttribute(parameters[parameters.Length - 1]);
- }
- private bool HasParamArrayAttribute(ParameterInfo info)
- {
- return info.IsDefined(typeof(ParamArrayAttribute), true);
- }
- private bool CalculateCandidateScore(CandidateMethod candidateMethod)
- {
- ParameterInfo[] parameters = candidateMethod.Parameters;
- for (int i = 0; i < candidateMethod.MinimumArgumentCount; ++i)
- {
- if (parameters[i].IsOut) return false;
- if (!CalculateCandidateArgumentScore(candidateMethod, i, parameters[i].ParameterType))
- {
- return false;
- }
- }
- if (candidateMethod.VarArgs)
- {
- Type varArgItemType = candidateMethod.VarArgsParameterType;
- for (int i = candidateMethod.MinimumArgumentCount; i < _arguments.Length; ++i)
- {
- if (!CalculateCandidateArgumentScore(candidateMethod, i, varArgItemType))
- {
- return false;
- }
- }
- }
- return true;
- }
- private bool CalculateCandidateArgumentScore(CandidateMethod candidateMethod, int argumentIndex, Type paramType)
- {
- int score = CandidateMethod.CalculateArgumentScore(paramType, _arguments[argumentIndex]);
- if (score < 0) return false;
- candidateMethod.ArgumentScores[argumentIndex] = score;
- return true;
- }
- }
- }