001 /*
002 * Copyright 2010-2013 JetBrains s.r.o.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package org.jetbrains.jet.lang.types.checker;
018
019 import org.jetbrains.annotations.NotNull;
020 import org.jetbrains.annotations.Nullable;
021 import org.jetbrains.jet.lang.descriptors.TypeParameterDescriptor;
022 import org.jetbrains.jet.lang.types.*;
023 import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
024
025 import java.util.List;
026
027 import static org.jetbrains.jet.lang.types.Variance.*;
028
029 public class TypeCheckingProcedure {
030
031 // This method returns the supertype of the first parameter that has the same constructor
032 // as the second parameter, applying the substitution of type arguments to it
033 @Nullable
034 public static JetType findCorrespondingSupertype(@NotNull JetType subtype, @NotNull JetType supertype) {
035 return findCorrespondingSupertype(subtype, supertype, new TypeCheckerTypingConstraints());
036 }
037
038 // This method returns the supertype of the first parameter that has the same constructor
039 // as the second parameter, applying the substitution of type arguments to it
040 @Nullable
041 public static JetType findCorrespondingSupertype(@NotNull JetType subtype, @NotNull JetType supertype, @NotNull TypingConstraints typingConstraints) {
042 TypeConstructor constructor = subtype.getConstructor();
043 if (typingConstraints.assertEqualTypeConstructors(constructor, supertype.getConstructor())) {
044 return subtype;
045 }
046 for (JetType immediateSupertype : constructor.getSupertypes()) {
047 JetType correspondingSupertype = findCorrespondingSupertype(immediateSupertype, supertype, typingConstraints);
048 if (correspondingSupertype != null) {
049 return TypeSubstitutor.create(subtype).safeSubstitute(correspondingSupertype, Variance.INVARIANT);
050 }
051 }
052 return null;
053 }
054
055 public static JetType getOutType(TypeParameterDescriptor parameter, TypeProjection argument) {
056 boolean isOutProjected = argument.getProjectionKind() == IN_VARIANCE || parameter.getVariance() == IN_VARIANCE;
057 return isOutProjected ? parameter.getUpperBoundsAsType() : argument.getType();
058 }
059
060 public static JetType getInType(TypeParameterDescriptor parameter, TypeProjection argument) {
061 boolean isOutProjected = argument.getProjectionKind() == OUT_VARIANCE || parameter.getVariance() == OUT_VARIANCE;
062 return isOutProjected ? KotlinBuiltIns.getInstance().getNothingType() : argument.getType();
063 }
064
065 private final TypingConstraints constraints;
066
067 public TypeCheckingProcedure(TypingConstraints constraints) {
068 this.constraints = constraints;
069 }
070
071 public boolean equalTypes(@NotNull JetType type1, @NotNull JetType type2) {
072 if (type1.isNullable() != type2.isNullable()) {
073 return false;
074 }
075
076 if (type1.isNullable()) {
077 // Then type2 is nullable, too (see the previous condition
078 return constraints.assertEqualTypes(TypeUtils.makeNotNullable(type1), TypeUtils.makeNotNullable(type2), this);
079 }
080
081 TypeConstructor constructor1 = type1.getConstructor();
082 TypeConstructor constructor2 = type2.getConstructor();
083
084 if (!constraints.assertEqualTypeConstructors(constructor1, constructor2)) {
085 return false;
086 }
087
088 List<TypeProjection> type1Arguments = type1.getArguments();
089 List<TypeProjection> type2Arguments = type2.getArguments();
090 if (type1Arguments.size() != type2Arguments.size()) {
091 return false;
092 }
093
094 for (int i = 0; i < type1Arguments.size(); i++) {
095 TypeParameterDescriptor typeParameter1 = constructor1.getParameters().get(i);
096 TypeProjection typeProjection1 = type1Arguments.get(i);
097 TypeParameterDescriptor typeParameter2 = constructor2.getParameters().get(i);
098 TypeProjection typeProjection2 = type2Arguments.get(i);
099 if (getEffectiveProjectionKind(typeParameter1, typeProjection1) != getEffectiveProjectionKind(typeParameter2, typeProjection2)) {
100 return false;
101 }
102
103 if (!constraints.assertEqualTypes(typeProjection1.getType(), typeProjection2.getType(), this)) {
104 return false;
105 }
106 }
107 return true;
108 }
109
110 public enum EnrichedProjectionKind {
111 IN, OUT, INV, STAR;
112
113 @NotNull
114 public static EnrichedProjectionKind fromVariance(@NotNull Variance variance) {
115 switch (variance) {
116 case INVARIANT:
117 return INV;
118 case IN_VARIANCE:
119 return IN;
120 case OUT_VARIANCE:
121 return OUT;
122 }
123 throw new IllegalStateException("Unknown variance");
124 }
125 }
126
127 // If class C<out T> then C<T> and C<out T> mean the same
128 // out * out = out
129 // out * in = *
130 // out * inv = out
131 //
132 // in * out = *
133 // in * in = in
134 // in * inv = in
135 //
136 // inv * out = out
137 // inv * in = out
138 // inv * inv = inv
139 public static EnrichedProjectionKind getEffectiveProjectionKind(
140 @NotNull TypeParameterDescriptor typeParameter,
141 @NotNull TypeProjection typeArgument
142 ) {
143 Variance a = typeParameter.getVariance();
144 Variance b = typeArgument.getProjectionKind();
145
146 // If they are not both invariant, let's make b not invariant for sure
147 if (b == INVARIANT) {
148 Variance t = a;
149 a = b;
150 b = t;
151 }
152
153 // Opposites yield STAR
154 if (a == IN_VARIANCE && b == OUT_VARIANCE) {
155 return EnrichedProjectionKind.STAR;
156 }
157 if (a == OUT_VARIANCE && b == IN_VARIANCE) {
158 return EnrichedProjectionKind.STAR;
159 }
160
161 // If they are not opposite, return b, because b is either equal to a or b is in/out and a is inv
162 return EnrichedProjectionKind.fromVariance(b);
163 }
164
165 public boolean isSubtypeOf(@NotNull JetType subtype, @NotNull JetType supertype) {
166 if (subtype.isError() || supertype.isError()) {
167 return true;
168 }
169 if (!supertype.isNullable() && subtype.isNullable()) {
170 return false;
171 }
172 subtype = TypeUtils.makeNotNullable(subtype);
173 supertype = TypeUtils.makeNotNullable(supertype);
174 if (KotlinBuiltIns.getInstance().isNothingOrNullableNothing(subtype)) {
175 return true;
176 }
177 @Nullable JetType closestSupertype = findCorrespondingSupertype(subtype, supertype, constraints);
178 if (closestSupertype == null) {
179 return constraints.noCorrespondingSupertype(subtype, supertype); // if this returns true, there still isn't any supertype to continue with
180 }
181
182 return checkSubtypeForTheSameConstructor(closestSupertype, supertype);
183 }
184
185 private boolean checkSubtypeForTheSameConstructor(@NotNull JetType subtype, @NotNull JetType supertype) {
186 TypeConstructor constructor = subtype.getConstructor();
187 assert constraints.assertEqualTypeConstructors(constructor, supertype.getConstructor()) : constructor + " is not " + supertype.getConstructor();
188
189 List<TypeProjection> subArguments = subtype.getArguments();
190 List<TypeProjection> superArguments = supertype.getArguments();
191 if (subArguments.size() != superArguments.size()) return false;
192
193 List<TypeParameterDescriptor> parameters = constructor.getParameters();
194 for (int i = 0; i < parameters.size(); i++) {
195 TypeParameterDescriptor parameter = parameters.get(i);
196
197 TypeProjection subArgument = subArguments.get(i);
198 JetType subIn = getInType(parameter, subArgument);
199 JetType subOut = getOutType(parameter, subArgument);
200
201 TypeProjection superArgument = superArguments.get(i);
202 JetType superIn = getInType(parameter, superArgument);
203 JetType superOut = getOutType(parameter, superArgument);
204
205 boolean argumentIsErrorType = subArgument.getType().isError() || superArgument.getType().isError();
206 if (!argumentIsErrorType && parameter.getVariance() == INVARIANT
207 && subArgument.getProjectionKind() == INVARIANT && superArgument.getProjectionKind() == INVARIANT) {
208 if (!constraints.assertEqualTypes(subArgument.getType(), superArgument.getType(), this)) return false;
209 }
210 else {
211 if (!constraints.assertSubtype(subOut, superOut, this)) return false;
212 if (!constraints.assertSubtype(superIn, subIn, this)) return false;
213 }
214 }
215 return true;
216 }
217 }