com.facebook.buck.util.MoreMaps.java Source code

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Here is the source code for com.facebook.buck.util.MoreMaps.java

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/*
 * Copyright 2015-present Facebook, Inc.
 *
 * 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.facebook.buck.util;

import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSortedMap;

import java.util.HashMap;
import java.util.Map;

import javax.annotation.Nullable;

public class MoreMaps {

    private MoreMaps() {
    }

    public static <K, V> Map<K, V> putCheckEquals(Map<K, V> map, K key, @Nullable V value) {
        V old = map.put(key, value);
        if (old != null) {
            Preconditions.checkState(old.equals(value));
        }
        return map;
    }

    public static <K1, K2, V> ImmutableMap<K2, V> transformKeys(Map<K1, V> map,
            Function<? super K1, K2> transformer) {
        ImmutableMap.Builder<K2, V> transformedMap = ImmutableMap.builder();
        for (Map.Entry<K1, V> ent : map.entrySet()) {
            transformedMap.put(Preconditions.checkNotNull(transformer.apply(ent.getKey())), ent.getValue());
        }
        return transformedMap.build();
    }

    public static <K, V> ImmutableMap<K, V> merge(Map<K, V> first, Map<K, V> second) {
        Map<K, V> mutableMap = new HashMap<>(first);
        mutableMap.putAll(second);
        return ImmutableMap.copyOf(mutableMap);
    }

    public static <K, V> ImmutableSortedMap<K, V> mergeSorted(Map<K, V> first, Map<K, V> second) {
        Map<K, V> mutableMap = new HashMap<>(first);
        mutableMap.putAll(second);
        return ImmutableSortedMap.copyOf(mutableMap);
    }
}