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.resolve.calls;
018    
019    import org.jetbrains.annotations.NotNull;
020    import org.jetbrains.annotations.Nullable;
021    import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
022    
023    import java.lang.ref.WeakReference;
024    import java.util.*;
025    
026    public class CallResolverExtensionProvider {
027    
028        private final static CompositeExtension DEFAULT =
029                new CompositeExtension(Arrays.asList(new NeedSyntheticCallResolverExtension(), new TypeParameterAsReifiedCheck()));
030    
031        private WeakReference<Map<DeclarationDescriptor, List<CallResolverExtension>>> extensionsCache;
032    
033        @NotNull
034        public CallResolverExtension createExtension(@Nullable DeclarationDescriptor descriptor) {
035            if (descriptor == null) {
036                return DEFAULT;
037            }
038            return new CompositeExtension(createExtensions(descriptor));
039        }
040    
041        // create extension list with default one at the end
042        @NotNull
043        private List<CallResolverExtension> createExtensions(@NotNull DeclarationDescriptor declaration) {
044            Map<DeclarationDescriptor, List<CallResolverExtension>> map;
045            if (extensionsCache == null || (map = extensionsCache.get()) == null) {
046                map = new HashMap<DeclarationDescriptor, List<CallResolverExtension>>();
047                extensionsCache = new WeakReference<Map<DeclarationDescriptor, List<CallResolverExtension>>>(map);
048            }
049    
050            List<CallResolverExtension> extensions = map.get(declaration);
051            if (extensions != null) {
052                return extensions;
053            }
054    
055            extensions = new ArrayList<CallResolverExtension>();
056    
057            DeclarationDescriptor parent = declaration.getContainingDeclaration();
058            if (parent != null) {
059                extensions.addAll(createExtensions(parent));
060                extensions.remove(extensions.size() - 1);//remove default from parent list
061            }
062    
063            appendExtensionsFor(declaration, extensions);
064    
065            List<CallResolverExtension> immutableResult = Collections.unmodifiableList(extensions);
066            map.put(declaration, immutableResult);
067    
068            return immutableResult;
069        }
070    
071        // with default one at the end
072        private void appendExtensionsFor(DeclarationDescriptor declarationDescriptor, List<CallResolverExtension> extensions) {
073            // add your extensions here
074            extensions.add(DEFAULT);
075        }
076    }