com.google.gwt.inject.client.multibindings.SimpleMultimap Maven / Gradle / Ivy

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/*
 * Copyright 2013 Google 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.google.gwt.inject.client.multibindings;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

/**
 * A very simple multimap implementation that supports conversion to unmodifiable map.
 */
class SimpleMultimap extends LinkedHashMap> {

  public void putItem(K key, V value) {
    Set set = get(key);
    if (set == null) {
      set = new LinkedHashSet();
      put(key, set);
    }
    set.add(value);
  }

  public Map> toUnmodifiable() {
    for (Entry> entry : entrySet()) {
      entry.setValue(Collections.unmodifiableSet(entry.getValue()));
    }
    return Collections.unmodifiableMap(this);
  }
}