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.k2js.translate.context.generator;
018    
019    import com.google.common.collect.Lists;
020    import com.google.common.collect.Maps;
021    import org.jetbrains.annotations.NotNull;
022    import org.jetbrains.annotations.Nullable;
023    import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
024    
025    import java.util.List;
026    import java.util.Map;
027    
028    public class Generator<V> {
029    
030    
031        @NotNull
032        private final Map<DeclarationDescriptor, V> values = Maps.newHashMap();
033        @NotNull
034        private final List<Rule<V>> rules = Lists.newArrayList();
035    
036        public void addRule(@NotNull Rule<V> rule) {
037            rules.add(rule);
038        }
039    
040        @Nullable
041        public V get(@NotNull DeclarationDescriptor descriptor) {
042            V result = values.get(descriptor);
043            if (result != null) {
044                return result;
045            }
046            result = generate(descriptor);
047            values.put(descriptor, result);
048            return result;
049        }
050    
051        @Nullable
052        private V generate(@NotNull DeclarationDescriptor descriptor) {
053            V result = null;
054            for (Rule<V> rule : rules) {
055                result = rule.apply(descriptor);
056                if (result != null) {
057                    return result;
058                }
059            }
060            return result;
061        }
062    }