edu.buaa.satla.analysis.util.ImmutableMapMerger.java Source code

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Here is the source code for edu.buaa.satla.analysis.util.ImmutableMapMerger.java

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/*
 *  CPAchecker is a tool for configurable software verification.
 *  This file is part of CPAchecker.
 *
 *  Copyright (C) 2007-2014  Dirk Beyer
 *  All rights reserved.
 *
 *  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.
 *
 *
 *  CPAchecker web page:
 *    http://cpachecker.sosy-lab.org
 */
package edu.buaa.satla.analysis.util;

import java.util.HashSet;
import java.util.Set;

import com.google.common.collect.ImmutableMap;

public class ImmutableMapMerger {
    public interface MergeFunc<K, V> {
        V apply(K key, V a, V b);
    }

    /**
     * Join two maps taking the key into account, use {@code func} on duplicate values.
     * @param a input map
     * @param b input map
     * @param func function to merge two values from different maps.
     * @return map containing the union of keys in {@code a} and {@code b}, which
     * contains the value from {@code a} if it contains only in {@code a}, value
     * from {@code b} if it is contained only in {@code b} and {@code func}
     * applied on value from {@code a} and a value from {@code b} otherwise.
     */
    public static <K, V> ImmutableMap<K, V> merge(ImmutableMap<K, V> a, ImmutableMap<K, V> b,
            MergeFunc<K, V> func) {
        Set<K> allKeys = new HashSet<>();

        allKeys.addAll(a.keySet());
        allKeys.addAll(b.keySet());

        ImmutableMap.Builder<K, V> builder = ImmutableMap.builder();

        for (K key : allKeys) {
            if (a.containsKey(key) && !b.containsKey(key)) {
                builder.put(key, a.get(key));
            } else if (!a.containsKey(key) && b.containsKey(key)) {
                builder.put(key, b.get(key));
            } else {
                builder.put(key, func.apply(key, a.get(key), b.get(key)));
            }
        }
        return builder.build();
    }
}