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source: branches/ProblemRefactoring/HeuristicLab.PluginInfrastructure/3.3/TypeExtensions.cs @ 13422

Last change on this file since 13422 was 13422, checked in by mkommend, 8 years ago

#2521: Adapted type discovery and type selector to allow the creation of generic programmable problems.

File size: 8.5 KB
Line 
1#region License Information
2
3/* HeuristicLab
4 * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
5 *
6 * This file is part of HeuristicLab.
7 *
8 * HeuristicLab is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, either version 3 of the License, or
11 * (at your option) any later version.
12 *
13 * HeuristicLab is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
20 */
21
22#endregion
23
24using System;
25using System.Collections.Generic;
26using System.Linq;
27using System.Reflection;
28
29namespace HeuristicLab.PluginInfrastructure {
30  internal static class TypeExtensions {
31    internal static bool IsNonDiscoverableType(this Type t) {
32      return t.GetCustomAttributes(typeof(NonDiscoverableTypeAttribute), false).Any();
33    }
34
35    /// <summary>
36    /// Constructs a concrete type from a given proto type.
37    /// </summary>
38    /// <param name="type"></param>
39    /// <param name="protoType"></param>
40    /// <returns>The constructed type, a generic type definition or null, if a type construction is not possible</returns>
41    /// <remarks>This method does not work with nested generic types</remarks>
42    internal static Type BuildType(this Type type, Type protoType) {
43      if (type == null || protoType == null) throw new ArgumentNullException();
44
45      if (!type.IsGenericTypeDefinition) return type;
46      if (protoType.IsGenericTypeDefinition) return type;
47      if (!protoType.IsGenericType) return type;
48
49      var typeGenericArguments = type.GetGenericArguments();
50      var protoTypeGenericArguments = protoType.GetGenericArguments();
51      if (typeGenericArguments.Length != protoTypeGenericArguments.Length) return null;
52
53      for (int i = 0; i < typeGenericArguments.Length; i++) {
54        var typeGenericArgument = typeGenericArguments[i];
55        var protoTypeGenericArgument = protoTypeGenericArguments[i];
56
57        //check class contraint on generic type parameter
58        if (typeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.ReferenceTypeConstraint))
59          if (!protoTypeGenericArgument.IsClass && !protoTypeGenericArgument.IsInterface && !protoType.IsArray) return null;
60
61        //check default constructor constraint on generic type parameter
62        if (typeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.DefaultConstructorConstraint))
63          if (!protoTypeGenericArgument.IsValueType && protoTypeGenericArgument.GetConstructor(Type.EmptyTypes) == null) return null;
64
65        //check type restrictions on generic type parameter
66        foreach (var constraint in typeGenericArgument.GetGenericParameterConstraints())
67          if (!constraint.IsAssignableFrom(protoTypeGenericArgument)) return null;
68      }
69
70      try {
71        return type.MakeGenericType(protoTypeGenericArguments);
72      }
73      catch (Exception) {
74        return null;
75      }
76    }
77
78    internal static bool IsAssignableTo(this Type subType, Type baseType) {
79      if (baseType.IsAssignableFrom(subType)) return true;
80
81      //check generics
82      if (!baseType.IsGenericType) return false;
83      if (RecursiveCheckGenericTypes(baseType, subType)) return true;
84
85      //check generic interfaces
86      IEnumerable<Type> implementedInterfaces = subType.GetInterfaces().Where(t => t.IsGenericType);
87      return implementedInterfaces.Any(implementedInterface => baseType.CheckGenericTypes(implementedInterface));
88    }
89
90    private static bool RecursiveCheckGenericTypes(Type baseType, Type subType) {
91      if (!baseType.IsGenericType) return false;
92      if (subType.IsGenericType && baseType.CheckGenericTypes(subType)) return true;
93      if (subType.BaseType == null) return false;
94
95      return RecursiveCheckGenericTypes(baseType, subType.BaseType);
96    }
97
98    private static bool CheckGenericTypes(this Type baseType, Type subType) {
99      var baseTypeGenericTypeDefinition = baseType.GetGenericTypeDefinition();
100      var subTypeGenericTypeDefinition = subType.GetGenericTypeDefinition();
101      if (baseTypeGenericTypeDefinition != subTypeGenericTypeDefinition) return false;
102
103      var baseTypeGenericArguments = baseType.GetGenericArguments();
104      var subTypeGenericArguments = subType.GetGenericArguments();
105
106      for (int i = 0; i < baseTypeGenericArguments.Length; i++) {
107        var baseTypeGenericArgument = baseTypeGenericArguments[i];
108        var subTypeGenericArgument = subTypeGenericArguments[i];
109
110        //no generic parameters => concrete types => check for type equality (ignore co- and contravariance)
111        //for example List<int> is only a List<int>, IParameter<IItem> is not a base type of IParameter<DoubleValue>
112        if (!baseTypeGenericArgument.IsGenericParameter && !subTypeGenericArgument.IsGenericParameter) {
113          if (baseTypeGenericArgument == subTypeGenericArgument) continue;
114          return false;
115        }
116
117        //baseTypeGenericArgument is a concrete type and the subTypeGenericArgument is a generic parameter
118        //for example List<int> is not a base type of List<T>
119        if (!baseTypeGenericArgument.IsGenericParameter && subTypeGenericArgument.IsGenericParameter) return false;
120
121        //baseTypeGenericArugment is a generic parameter and the subTypeGenericArgument is a concrete type => check type constraints
122        //for example IParameter<T> is a base type of IParameter<IItem> if all generic contraints on T are fulfilled
123        if (baseTypeGenericArgument.IsGenericParameter && !subTypeGenericArgument.IsGenericParameter) {
124          if (baseTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.ReferenceTypeConstraint) &&
125            subTypeGenericArgument.IsValueType) return false;
126          if (baseTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.DefaultConstructorConstraint) &&
127            subTypeGenericArgument.GetConstructor(Type.EmptyTypes) == null) return false;
128          if (baseTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.NotNullableValueTypeConstraint)) {
129            if (!subTypeGenericArgument.IsValueType) return false;
130            if (subTypeGenericArgument.IsGenericType && subTypeGenericArgument.GetGenericTypeDefinition() == typeof(Nullable<>))
131              return false;
132          }
133
134          //not assignable if the subTypeGenericArgument is not assignable to all of the constraints of the base type
135          if (baseTypeGenericArgument.GetGenericParameterConstraints().Any(baseTypeGenericParameterConstraint =>
136            !baseTypeGenericParameterConstraint.IsAssignableFrom(subTypeGenericArgument)))
137            return false;
138        }
139
140        //both generic arguments are generic parameters => check type constraints
141        //for example IParameter<T> is a base type of IParameter<T>
142        if (baseTypeGenericArgument.IsGenericParameter && subTypeGenericArgument.IsGenericParameter) {
143          if (baseTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.ReferenceTypeConstraint) &&
144              !subTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.ReferenceTypeConstraint)) return false;
145          if (baseTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.DefaultConstructorConstraint) &&
146              !subTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.DefaultConstructorConstraint)) return false;
147          if (baseTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.NotNullableValueTypeConstraint) &&
148              !subTypeGenericArgument.GenericParameterAttributes.HasFlag(GenericParameterAttributes.NotNullableValueTypeConstraint)) return false;
149
150          //not assignable if any of the constraints is not assignable to the constraints of the base type
151          if (baseTypeGenericArgument.GetGenericParameterConstraints().Any(baseTypeGenericParameterConstraint => !subTypeGenericArgument.GetGenericParameterConstraints().Any(t => baseTypeGenericParameterConstraint.IsAssignableFrom(t)))) {
152            return false;
153          }
154        }
155      }
156      return true;
157    }
158  }
159}
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