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.jet.util;
018
019import com.google.common.base.Supplier;
020import com.google.common.collect.*;
021
022import java.util.Collection;
023import java.util.List;
024import java.util.Set;
025
026public class CommonSuppliers {
027    private CommonSuppliers() {}
028
029    private static final Supplier<?> ARRAY_LIST_SUPPLIER = new Supplier() {
030        @Override
031        public List get() {
032            return Lists.newArrayList();
033        }
034    };
035
036    private static final Supplier<?> LINKED_HASH_SET_SUPPLIER = new Supplier() {
037        @Override
038        public Set get() {
039            return Sets.newLinkedHashSet();
040        }
041    };
042
043    private static final Supplier<?> HASH_SET_SUPPLIER = new Supplier() {
044        @Override
045        public Set get() {
046            return Sets.newHashSet();
047        }
048    };
049
050    public static <T> Supplier<List<T>> getArrayListSupplier() {
051        //noinspection unchecked
052        return (Supplier<List<T>>) ARRAY_LIST_SUPPLIER;
053    }
054
055    public static <T> Supplier<Set<T>> getLinkedHashSetSupplier() {
056        //noinspection unchecked
057        return (Supplier<Set<T>>) LINKED_HASH_SET_SUPPLIER;
058    }
059
060    public static <T> Supplier<Set<T>> getHashSetSupplier() {
061        //noinspection unchecked
062        return (Supplier<Set<T>>) HASH_SET_SUPPLIER;
063    }
064
065    public static <K, V> SetMultimap<K, V> newLinkedHashSetHashSetMultimap() {
066        return Multimaps.newSetMultimap(Maps.<K, Collection<V>>newHashMap(), CommonSuppliers.<V>getLinkedHashSetSupplier());
067    }
068}