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 TypeConstructor constructor = subtype.getConstructor();
036 if (constructor.equals(supertype.getConstructor())) {
037 return subtype;
038 }
039 for (JetType immediateSupertype : constructor.getSupertypes()) {
040 JetType correspondingSupertype = findCorrespondingSupertype(immediateSupertype, supertype);
041 if (correspondingSupertype != null) {
042 return TypeSubstitutor.create(subtype).safeSubstitute(correspondingSupertype, Variance.INVARIANT);
043 }
044 }
045 return null;
046 }
047
048 public static JetType getOutType(TypeParameterDescriptor parameter, TypeProjection argument) {
049 boolean isOutProjected = argument.getProjectionKind() == IN_VARIANCE || parameter.getVariance() == IN_VARIANCE;
050 return isOutProjected ? parameter.getUpperBoundsAsType() : argument.getType();
051 }
052
053 public static JetType getInType(TypeParameterDescriptor parameter, TypeProjection argument) {
054 boolean isOutProjected = argument.getProjectionKind() == OUT_VARIANCE || parameter.getVariance() == OUT_VARIANCE;
055 return isOutProjected ? KotlinBuiltIns.getInstance().getNothingType() : argument.getType();
056 }
057
058 private final TypingConstraints constraints;
059
060 public TypeCheckingProcedure(TypingConstraints constraints) {
061 this.constraints = constraints;
062 }
063
064 public boolean equalTypes(@NotNull JetType type1, @NotNull JetType type2) {
065 if (type1.isNullable() != type2.isNullable()) {
066 return false;
067 }
068
069 if (type1.isNullable()) {
070 // Then type2 is nullable, too (see the previous condition
071 return constraints.assertEqualTypes(TypeUtils.makeNotNullable(type1), TypeUtils.makeNotNullable(type2), this);
072 }
073
074 TypeConstructor constructor1 = type1.getConstructor();
075 TypeConstructor constructor2 = type2.getConstructor();
076
077 if (!constraints.assertEqualTypeConstructors(constructor1, constructor2)) {
078 return false;
079 }
080
081 List<TypeProjection> type1Arguments = type1.getArguments();
082 List<TypeProjection> type2Arguments = type2.getArguments();
083 if (type1Arguments.size() != type2Arguments.size()) {
084 return false;
085 }
086
087 for (int i = 0; i < type1Arguments.size(); i++) {
088 TypeParameterDescriptor typeParameter1 = constructor1.getParameters().get(i);
089 TypeProjection typeProjection1 = type1Arguments.get(i);
090 TypeParameterDescriptor typeParameter2 = constructor2.getParameters().get(i);
091 TypeProjection typeProjection2 = type2Arguments.get(i);
092 if (getEffectiveProjectionKind(typeParameter1, typeProjection1) != getEffectiveProjectionKind(typeParameter2, typeProjection2)) {
093 return false;
094 }
095
096 if (!constraints.assertEqualTypes(typeProjection1.getType(), typeProjection2.getType(), this)) {
097 return false;
098 }
099 }
100 return true;
101 }
102
103 public enum EnrichedProjectionKind {
104 IN, OUT, INV, STAR;
105
106 @NotNull
107 public static EnrichedProjectionKind fromVariance(@NotNull Variance variance) {
108 switch (variance) {
109 case INVARIANT:
110 return INV;
111 case IN_VARIANCE:
112 return IN;
113 case OUT_VARIANCE:
114 return OUT;
115 }
116 throw new IllegalStateException("Unknown variance");
117 }
118 }
119
120 // If class C<out T> then C<T> and C<out T> mean the same
121 // out * out = out
122 // out * in = *
123 // out * inv = out
124 //
125 // in * out = *
126 // in * in = in
127 // in * inv = in
128 //
129 // inv * out = out
130 // inv * in = out
131 // inv * inv = inv
132 public static EnrichedProjectionKind getEffectiveProjectionKind(
133 @NotNull TypeParameterDescriptor typeParameter,
134 @NotNull TypeProjection typeArgument
135 ) {
136 Variance a = typeParameter.getVariance();
137 Variance b = typeArgument.getProjectionKind();
138
139 // If they are not both invariant, let's make b not invariant for sure
140 if (b == INVARIANT) {
141 Variance t = a;
142 a = b;
143 b = t;
144 }
145
146 // Opposites yield STAR
147 if (a == IN_VARIANCE && b == OUT_VARIANCE) {
148 return EnrichedProjectionKind.STAR;
149 }
150 if (a == OUT_VARIANCE && b == IN_VARIANCE) {
151 return EnrichedProjectionKind.STAR;
152 }
153
154 // If they are not opposite, return b, because b is either equal to a or b is in/out and a is inv
155 return EnrichedProjectionKind.fromVariance(b);
156 }
157
158 public boolean isSubtypeOf(@NotNull JetType subtype, @NotNull JetType supertype) {
159 if (ErrorUtils.isErrorType(subtype) || ErrorUtils.isErrorType(supertype)) {
160 return true;
161 }
162 if (!supertype.isNullable() && subtype.isNullable()) {
163 return false;
164 }
165 subtype = TypeUtils.makeNotNullable(subtype);
166 supertype = TypeUtils.makeNotNullable(supertype);
167 if (KotlinBuiltIns.getInstance().isNothingOrNullableNothing(subtype)) {
168 return true;
169 }
170 @Nullable JetType closestSupertype = findCorrespondingSupertype(subtype, supertype);
171 if (closestSupertype == null) {
172 return constraints.noCorrespondingSupertype(subtype, supertype); // if this returns true, there still isn't any supertype to continue with
173 }
174
175 return checkSubtypeForTheSameConstructor(closestSupertype, supertype);
176 }
177
178 private boolean checkSubtypeForTheSameConstructor(@NotNull JetType subtype, @NotNull JetType supertype) {
179 TypeConstructor constructor = subtype.getConstructor();
180 assert constructor.equals(supertype.getConstructor()) : constructor + " is not " + supertype.getConstructor();
181
182 List<TypeProjection> subArguments = subtype.getArguments();
183 List<TypeProjection> superArguments = supertype.getArguments();
184 List<TypeParameterDescriptor> parameters = constructor.getParameters();
185 for (int i = 0; i < parameters.size(); i++) {
186 TypeParameterDescriptor parameter = parameters.get(i);
187
188
189 TypeProjection subArgument = subArguments.get(i);
190 JetType subIn = getInType(parameter, subArgument);
191 JetType subOut = getOutType(parameter, subArgument);
192
193 TypeProjection superArgument = superArguments.get(i);
194 JetType superIn = getInType(parameter, superArgument);
195 JetType superOut = getOutType(parameter, superArgument);
196
197 boolean argumentIsErrorType = ErrorUtils.isErrorType(subArgument.getType()) || ErrorUtils.isErrorType(superArgument.getType());
198 if (!argumentIsErrorType && parameter.getVariance() == INVARIANT
199 && subArgument.getProjectionKind() == INVARIANT && superArgument.getProjectionKind() == INVARIANT) {
200 if (!constraints.assertEqualTypes(subArgument.getType(), superArgument.getType(), this)) return false;
201 }
202 else {
203 if (!constraints.assertSubtype(subOut, superOut, this)) return false;
204 if (!constraints.assertSubtype(superIn, subIn, this)) return false;
205 }
206 }
207 return true;
208 }
209 }