pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / analysis / tokenattributes / PositionIncrementAttributeImpl.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/analysis/tokenattributes/PositionIncrementAttributeImpl.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/analysis/tokenattributes/PositionIncrementAttributeImpl.java
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+package org.apache.lucene.analysis.tokenattributes;
+
+/**
+ * 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 org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.util.AttributeImpl;
+
+/** The positionIncrement determines the position of this token
+ * relative to the previous Token in a {@link TokenStream}, used in phrase
+ * searching.
+ *
+ * <p>The default value is one.
+ *
+ * <p>Some common uses for this are:<ul>
+ *
+ * <li>Set it to zero to put multiple terms in the same position.  This is
+ * useful if, e.g., a word has multiple stems.  Searches for phrases
+ * including either stem will match.  In this case, all but the first stem's
+ * increment should be set to zero: the increment of the first instance
+ * should be one.  Repeating a token with an increment of zero can also be
+ * used to boost the scores of matches on that token.
+ *
+ * <li>Set it to values greater than one to inhibit exact phrase matches.
+ * If, for example, one does not want phrases to match across removed stop
+ * words, then one could build a stop word filter that removes stop words and
+ * also sets the increment to the number of stop words removed before each
+ * non-stop word.  Then exact phrase queries will only match when the terms
+ * occur with no intervening stop words.
+ *
+ * </ul>
+ */
+public class PositionIncrementAttributeImpl extends AttributeImpl implements PositionIncrementAttribute, Cloneable, Serializable {
+  private int positionIncrement = 1;
+  
+  /** Set the position increment. The default value is one.
+   *
+   * @param positionIncrement the distance from the prior term
+   */
+  public void setPositionIncrement(int positionIncrement) {
+    if (positionIncrement < 0)
+      throw new IllegalArgumentException
+        ("Increment must be zero or greater: " + positionIncrement);
+    this.positionIncrement = positionIncrement;
+  }
+
+  /** Returns the position increment of this Token.
+   * @see #setPositionIncrement
+   */
+  public int getPositionIncrement() {
+    return positionIncrement;
+  }
+
+  @Override
+  public void clear() {
+    this.positionIncrement = 1;
+  }
+  
+  @Override
+  public boolean equals(Object other) {
+    if (other == this) {
+      return true;
+    }
+    
+    if (other instanceof PositionIncrementAttributeImpl) {
+      return positionIncrement == ((PositionIncrementAttributeImpl) other).positionIncrement;
+    }
+ 
+    return false;
+  }
+
+  @Override
+  public int hashCode() {
+    return positionIncrement;
+  }
+  
+  @Override
+  public void copyTo(AttributeImpl target) {
+    PositionIncrementAttribute t = (PositionIncrementAttribute) target;
+    t.setPositionIncrement(positionIncrement);
+  }  
+
+}