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
017package org.jetbrains.k2js.translate.context.generator;
018
019import com.google.common.collect.Lists;
020import com.google.common.collect.Maps;
021import org.jetbrains.annotations.NotNull;
022import org.jetbrains.annotations.Nullable;
023import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
024
025import java.util.List;
026import java.util.Map;
027
028public 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}