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 (TypesPackage.isFlexible(type1)) {
073 if (TypesPackage.isFlexible(type2)) {
074 return !type1.isError() && !type2.isError() && isSubtypeOf(type1, type2) && isSubtypeOf(type2, type1);
075 }
076 return heterogeneousEquivalence(type2, type1);
077 }
078 else if (TypesPackage.isFlexible(type2)) {
079 return heterogeneousEquivalence(type1, type2);
080 }
081
082 if (type1.isNullable() != type2.isNullable()) {
083 return false;
084 }
085
086 if (type1.isNullable()) {
087 // Then type2 is nullable, too (see the previous condition
088 return constraints.assertEqualTypes(TypeUtils.makeNotNullable(type1), TypeUtils.makeNotNullable(type2), this);
089 }
090
091 TypeConstructor constructor1 = type1.getConstructor();
092 TypeConstructor constructor2 = type2.getConstructor();
093
094 if (!constraints.assertEqualTypeConstructors(constructor1, constructor2)) {
095 return false;
096 }
097
098 List<TypeProjection> type1Arguments = type1.getArguments();
099 List<TypeProjection> type2Arguments = type2.getArguments();
100 if (type1Arguments.size() != type2Arguments.size()) {
101 return false;
102 }
103
104 for (int i = 0; i < type1Arguments.size(); i++) {
105 TypeParameterDescriptor typeParameter1 = constructor1.getParameters().get(i);
106 TypeProjection typeProjection1 = type1Arguments.get(i);
107 TypeParameterDescriptor typeParameter2 = constructor2.getParameters().get(i);
108 TypeProjection typeProjection2 = type2Arguments.get(i);
109 if (getEffectiveProjectionKind(typeParameter1, typeProjection1) != getEffectiveProjectionKind(typeParameter2, typeProjection2)) {
110 return false;
111 }
112
113 if (!constraints.assertEqualTypes(typeProjection1.getType(), typeProjection2.getType(), this)) {
114 return false;
115 }
116 }
117 return true;
118 }
119
120 protected boolean heterogeneousEquivalence(JetType inflexibleType, JetType flexibleType) {
121 // This is to account for the case when we have Collection<X> vs (Mutable)Collection<X>! or K(java.util.Collection<? extends X>)
122 assert !TypesPackage.isFlexible(inflexibleType) : "Only inflexible types are allowed here: " + inflexibleType;
123 return isSubtypeOf(TypesPackage.flexibility(flexibleType).getLowerBound(), inflexibleType)
124 && isSubtypeOf(inflexibleType, TypesPackage.flexibility(flexibleType).getUpperBound());
125 }
126
127 public enum EnrichedProjectionKind {
128 IN, OUT, INV, STAR;
129
130 @NotNull
131 public static EnrichedProjectionKind fromVariance(@NotNull Variance variance) {
132 switch (variance) {
133 case INVARIANT:
134 return INV;
135 case IN_VARIANCE:
136 return IN;
137 case OUT_VARIANCE:
138 return OUT;
139 }
140 throw new IllegalStateException("Unknown variance");
141 }
142 }
143
144 // If class C<out T> then C<T> and C<out T> mean the same
145 // out * out = out
146 // out * in = *
147 // out * inv = out
148 //
149 // in * out = *
150 // in * in = in
151 // in * inv = in
152 //
153 // inv * out = out
154 // inv * in = out
155 // inv * inv = inv
156 public static EnrichedProjectionKind getEffectiveProjectionKind(
157 @NotNull TypeParameterDescriptor typeParameter,
158 @NotNull TypeProjection typeArgument
159 ) {
160 Variance a = typeParameter.getVariance();
161 Variance b = typeArgument.getProjectionKind();
162
163 // If they are not both invariant, let's make b not invariant for sure
164 if (b == INVARIANT) {
165 Variance t = a;
166 a = b;
167 b = t;
168 }
169
170 // Opposites yield STAR
171 if (a == IN_VARIANCE && b == OUT_VARIANCE) {
172 return EnrichedProjectionKind.STAR;
173 }
174 if (a == OUT_VARIANCE && b == IN_VARIANCE) {
175 return EnrichedProjectionKind.STAR;
176 }
177
178 // If they are not opposite, return b, because b is either equal to a or b is in/out and a is inv
179 return EnrichedProjectionKind.fromVariance(b);
180 }
181
182 public boolean isSubtypeOf(@NotNull JetType subtype, @NotNull JetType supertype) {
183 if (TypesPackage.isFlexible(subtype)) {
184 return isSubtypeOf(TypesPackage.flexibility(subtype).getLowerBound(), supertype);
185 }
186 if (TypesPackage.isFlexible(supertype)) {
187 return isSubtypeOf(subtype, TypesPackage.flexibility(supertype).getUpperBound());
188 }
189 if (subtype.isError() || supertype.isError()) {
190 return true;
191 }
192 if (!supertype.isNullable() && subtype.isNullable()) {
193 return false;
194 }
195 subtype = TypeUtils.makeNotNullable(subtype);
196 supertype = TypeUtils.makeNotNullable(supertype);
197 if (KotlinBuiltIns.getInstance().isNothingOrNullableNothing(subtype)) {
198 return true;
199 }
200 @Nullable JetType closestSupertype = findCorrespondingSupertype(subtype, supertype, constraints);
201 if (closestSupertype == null) {
202 return constraints.noCorrespondingSupertype(subtype, supertype); // if this returns true, there still isn't any supertype to continue with
203 }
204
205 return checkSubtypeForTheSameConstructor(closestSupertype, supertype);
206 }
207
208 private boolean checkSubtypeForTheSameConstructor(@NotNull JetType subtype, @NotNull JetType supertype) {
209 TypeConstructor constructor = subtype.getConstructor();
210 assert constraints.assertEqualTypeConstructors(constructor, supertype.getConstructor()) : constructor + " is not " + supertype.getConstructor();
211
212 List<TypeProjection> subArguments = subtype.getArguments();
213 List<TypeProjection> superArguments = supertype.getArguments();
214 if (subArguments.size() != superArguments.size()) return false;
215
216 List<TypeParameterDescriptor> parameters = constructor.getParameters();
217 for (int i = 0; i < parameters.size(); i++) {
218 TypeParameterDescriptor parameter = parameters.get(i);
219
220 TypeProjection subArgument = subArguments.get(i);
221 JetType subIn = getInType(parameter, subArgument);
222 JetType subOut = getOutType(parameter, subArgument);
223
224 TypeProjection superArgument = superArguments.get(i);
225 JetType superIn = getInType(parameter, superArgument);
226 JetType superOut = getOutType(parameter, superArgument);
227
228 boolean argumentIsErrorType = subArgument.getType().isError() || superArgument.getType().isError();
229 if (!argumentIsErrorType && parameter.getVariance() == INVARIANT
230 && subArgument.getProjectionKind() == INVARIANT && superArgument.getProjectionKind() == INVARIANT) {
231 if (!constraints.assertEqualTypes(subArgument.getType(), superArgument.getType(), this)) return false;
232 }
233 else {
234 if (!constraints.assertSubtype(subOut, superOut, this)) return false;
235 if (!constraints.assertSubtype(superIn, subIn, this)) return false;
236 }
237 }
238 return true;
239 }
240 }