presto.android.MultiMapUtil.java Source code

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Here is the source code for presto.android.MultiMapUtil.java

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/*
 * MultiMapUtil.java - part of the GATOR project
 *
 * Copyright (c) 2014, The Ohio State University
 *
 * This file is distributed under the terms described in LICENSE in the
 * root directory.
 */
package presto.android;

import java.util.Collections;
import java.util.Map;
import java.util.Set;

import com.google.common.collect.Sets;

// Handy helper methods for multimap (key -> set(value)).
public class MultiMapUtil {
    public static <Key, HashSetElement, SubClassOfHashSetElement extends HashSetElement> void addKeyAndHashSetElement(
            Map<Key, Set<HashSetElement>> map, Key key, SubClassOfHashSetElement element) {
        Set<HashSetElement> set = map.get(key);
        if (set == null) {
            set = Sets.newHashSet();
            map.put(key, set);
        }
        set.add(element);
    }

    public static <Key, HashSetElement, SubClassOfHashSetElement extends HashSetElement> void addKeyAndHashSet(
            Map<Key, Set<HashSetElement>> map, Key key, Set<SubClassOfHashSetElement> elements) {
        Set<HashSetElement> set = map.get(key);
        if (set == null) {
            set = Sets.newHashSet();
            map.put(key, set);
        }
        set.addAll(elements);
    }

    public static <Key, HashSetElement> Set<HashSetElement> getNonNullHashSetByKey(
            Map<Key, Set<HashSetElement>> map, Key key) {
        Set<HashSetElement> set = map.get(key);
        if (set == null) {
            set = Collections.emptySet();
        }
        return set;
    }

    public static <Key, HashSetElement, SubClassOfHashSetElement extends HashSetElement> boolean contains(
            Map<Key, Set<HashSetElement>> map, Key key, SubClassOfHashSetElement element) {
        Set<HashSetElement> set = map.get(key);
        return (set != null && set.contains(element));
    }
}