pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / util / MapBackedSet.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/MapBackedSet.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/MapBackedSet.java
new file mode 100644 (file)
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--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/MapBackedSet.java
@@ -0,0 +1,73 @@
+package org.apache.lucene.util;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+import java.io.Serializable;
+import java.util.AbstractSet;
+import java.util.Iterator;
+import java.util.Map;
+
+/**
+ * A Set implementation that wraps an actual Map based
+ * implementation.
+ * 
+ * @lucene.internal
+ */
+public final class MapBackedSet<E> extends AbstractSet<E> implements Serializable {
+
+  private static final long serialVersionUID = -6761513279741915432L;
+
+  private final Map<E, Boolean> map;
+
+  /**
+   * Creates a new instance which wraps the specified {@code map}.
+   */
+  public MapBackedSet(Map<E, Boolean> map) {
+    this.map = map;
+  }
+
+  @Override
+  public int size() {
+    return map.size();
+  }
+
+  @Override
+  public boolean contains(Object o) {
+    return map.containsKey(o);
+  }
+
+  @Override
+  public boolean add(E o) {
+    return map.put(o, Boolean.TRUE) == null;
+  }
+
+  @Override
+  public boolean remove(Object o) {
+    return map.remove(o) != null;
+  }
+
+  @Override
+  public void clear() {
+    map.clear();
+  }
+
+  @Override
+  public Iterator<E> iterator() {
+    return map.keySet().iterator();
+  }
+}