001    /*
002     * Copyright 2010-2015 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.kotlin.js.translate.context;
018    
019    import com.google.dart.compiler.backend.js.ast.JsExpression;
020    import gnu.trove.THashMap;
021    import org.jetbrains.annotations.NotNull;
022    import org.jetbrains.annotations.Nullable;
023    import org.jetbrains.kotlin.descriptors.DeclarationDescriptor;
024    import org.jetbrains.kotlin.psi.KtExpression;
025    
026    import java.util.Collections;
027    import java.util.Map;
028    
029    public class AliasingContext {
030        public static AliasingContext getCleanContext() {
031            return new AliasingContext(null, null, null);
032        }
033    
034        @Nullable
035        private Map<DeclarationDescriptor, JsExpression> aliasesForDescriptors;
036    
037        @Nullable
038        private final Map<KtExpression, JsExpression> aliasesForExpressions;
039    
040        @Nullable
041        private final AliasingContext parent;
042    
043        private AliasingContext(
044                @Nullable AliasingContext parent,
045                @Nullable Map<DeclarationDescriptor, JsExpression> aliasesForDescriptors,
046                @Nullable Map<KtExpression, JsExpression> aliasesForExpressions
047        ) {
048            this.parent = parent;
049            this.aliasesForDescriptors = aliasesForDescriptors;
050            this.aliasesForExpressions = aliasesForExpressions;
051        }
052    
053        @NotNull
054        public AliasingContext inner() {
055            return new AliasingContext(this, null, null);
056        }
057    
058        @NotNull
059        public AliasingContext inner(@NotNull DeclarationDescriptor descriptor, @NotNull JsExpression alias) {
060            return new AliasingContext(this, Collections.singletonMap(descriptor, alias), null);
061        }
062    
063        @NotNull
064        public AliasingContext withExpressionsAliased(@NotNull Map<KtExpression, JsExpression> aliasesForExpressions) {
065            return new AliasingContext(this, null, aliasesForExpressions);
066        }
067    
068        @NotNull
069        public AliasingContext withDescriptorsAliased(@NotNull Map<DeclarationDescriptor, JsExpression> aliases) {
070            return new AliasingContext(this, aliases, null);
071        }
072    
073    
074        @Nullable
075        final public JsExpression getAliasForDescriptor(@NotNull DeclarationDescriptor descriptor) {
076            // these aliases cannot be shared and applicable only in current context
077            return getAliasForDescriptor(descriptor, false);
078        }
079    
080        @Nullable
081        protected JsExpression getAliasForDescriptor(@NotNull DeclarationDescriptor descriptor, boolean fromChild) {
082            JsExpression alias = aliasesForDescriptors == null ? null : aliasesForDescriptors.get(descriptor.getOriginal());
083            return alias != null || parent == null ? alias : parent.getAliasForDescriptor(descriptor, true);
084        }
085    
086        @Nullable
087        public JsExpression getAliasForExpression(@NotNull KtExpression element) {
088            JsExpression alias = aliasesForExpressions == null ? null : aliasesForExpressions.get(element);
089            return alias != null || parent == null ? alias : parent.getAliasForExpression(element);
090        }
091    
092        /**
093         * Usages:
094         * 1) Local variable captured in closure. If captured in closure, any modification in closure should affect captured variable.
095         * So, "var count = n" wrapped as "var count = {v: n}". descriptor wil be property descriptor, alias will be JsObjectLiteral
096         *
097         * 2) Local named function.
098         */
099        public void registerAlias(@NotNull DeclarationDescriptor descriptor, @NotNull JsExpression alias) {
100            if (aliasesForDescriptors == null) {
101                aliasesForDescriptors = Collections.singletonMap(descriptor, alias);
102            }
103            else {
104                if (aliasesForDescriptors.size() == 1) {
105                    Map<DeclarationDescriptor, JsExpression> singletonMap = aliasesForDescriptors;
106                    aliasesForDescriptors = new THashMap<DeclarationDescriptor, JsExpression>();
107                    aliasesForDescriptors.put(singletonMap.keySet().iterator().next(), singletonMap.values().iterator().next());
108                }
109                JsExpression prev = aliasesForDescriptors.put(descriptor, alias);
110                assert prev == null : "Alias for descriptor already registered." +
111                                      " Descriptor: " + descriptor +
112                                      " prev alias: " + prev +
113                                      " new alias: " + alias;
114            }
115        }
116    }