com.google.common.collect.Platform.java Source code

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Here is the source code for com.google.common.collect.Platform.java

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/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.collect.Maps.EntryTransformer;

import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Deque;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;

import javax.annotation.Nullable;

/**
 * Minimal GWT emulation of {@code com.google.common.collect.Platform}.
 *
 * <p><strong>This .java file should never be consumed by javac.</strong>
 *
 * @author Hayward Chan
 */
final class Platform {

    static <T> T[] newArray(T[] reference, int length) {
        return GwtPlatform.newArray(reference, length);
    }

    /*
     * Regarding newSetForMap() and SetFromMap:
     *
     * Written by Doug Lea with assistance from members of JCP JSR-166
     * Expert Group and released to the public domain, as explained at
     * http://creativecommons.org/licenses/publicdomain
     */

    static <E> Set<E> newSetFromMap(Map<E, Boolean> map) {
        return new SetFromMap<E>(map);
    }

    private static class SetFromMap<E> extends AbstractSet<E> implements Set<E>, Serializable {
        private final Map<E, Boolean> m; // The backing map
        private transient Set<E> s; // Its keySet

        SetFromMap(Map<E, Boolean> map) {
            checkArgument(map.isEmpty(), "Map is non-empty");
            m = map;
            s = map.keySet();
        }

        @Override
        public void clear() {
            m.clear();
        }

        @Override
        public int size() {
            return m.size();
        }

        @Override
        public boolean isEmpty() {
            return m.isEmpty();
        }

        @Override
        public boolean contains(Object o) {
            return m.containsKey(o);
        }

        @Override
        public boolean remove(Object o) {
            return m.remove(o) != null;
        }

        @Override
        public boolean add(E e) {
            return m.put(e, Boolean.TRUE) == null;
        }

        @Override
        public Iterator<E> iterator() {
            return s.iterator();
        }

        @Override
        public Object[] toArray() {
            return s.toArray();
        }

        @Override
        public <T> T[] toArray(T[] a) {
            return s.toArray(a);
        }

        @Override
        public String toString() {
            return s.toString();
        }

        @Override
        public int hashCode() {
            return s.hashCode();
        }

        @Override
        public boolean equals(@Nullable Object object) {
            return this == object || this.s.equals(object);
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            return s.containsAll(c);
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            return s.removeAll(c);
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            return s.retainAll(c);
        }
    }

    static MapMaker tryWeakKeys(MapMaker mapMaker) {
        return mapMaker;
    }

    static <K, V1, V2> SortedMap<K, V2> mapsTransformEntriesSortedMap(SortedMap<K, V1> fromMap,
            EntryTransformer<? super K, ? super V1, V2> transformer) {
        return Maps.transformEntriesIgnoreNavigable(fromMap, transformer);
    }

    static <K, V> SortedMap<K, V> mapsAsMapSortedSet(SortedSet<K> set, Function<? super K, V> function) {
        return Maps.asMapSortedIgnoreNavigable(set, function);
    }

    static <E> SortedSet<E> setsFilterSortedSet(SortedSet<E> unfiltered, Predicate<? super E> predicate) {
        return Sets.filterSortedIgnoreNavigable(unfiltered, predicate);
    }

    static <K, V> SortedMap<K, V> mapsFilterSortedMap(SortedMap<K, V> unfiltered,
            Predicate<? super Map.Entry<K, V>> predicate) {
        return Maps.filterSortedIgnoreNavigable(unfiltered, predicate);
    }

    static <E> Deque<E> newFastestDeque(int ignored) {
        return new LinkedList<E>();
    }

    private Platform() {
    }
}