LUCENE-3671: Add TypeTokenFilter that filters tokens based on their TypeAttribute

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1234396 13f79535-47bb-0310-9956-ffa450edef68

lucene/CHANGES.txt

@@ -790,6 +790,9 @@ New Features
   input mapping to it) for FSTs that have strictly monotonic long
   outputs (such as an ord).  (Mike McCandless)
   
+* LUCENE-3121: Add TypeTokenFilter that filters tokens based on
+  their TypeAttribute.  (Tommaso Teofili via Uwe Schindler)
+  
 Bug fixes
 
 * LUCENE-3595: Fixed FieldCacheRangeFilter and FieldCacheTermsFilter

modules/analysis/common/src/java/org/apache/lucene/analysis/core/TypeTokenFilter.java

@@ -0,0 +1,47 @@
+package org.apache.lucene.analysis.core;
+
+/*
+ * 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 org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
+import org.apache.lucene.analysis.util.FilteringTokenFilter;
+
+import java.io.IOException;
+import java.util.Set;
+
+/**
+ * Removes tokens whose types appear in a set of blocked types from a token stream.
+ */
+public final class TypeTokenFilter extends FilteringTokenFilter {
+
+  private final Set<String> stopTypes;
+  private final TypeAttribute typeAttribute = addAttribute(TypeAttribute.class);
+
+  public TypeTokenFilter(boolean enablePositionIncrements, TokenStream input, Set<String> stopTypes) {
+    super(enablePositionIncrements, input);
+    this.stopTypes = stopTypes;
+  }
+
+  /**
+   * Returns the next input Token whose typeAttribute.type() is not a stop type.
+   */
+  @Override
+  protected boolean accept() throws IOException {
+    return !stopTypes.contains(typeAttribute.type());
+  }
+}

modules/analysis/common/src/test/org/apache/lucene/analysis/core/TestTypeTokenFilter.java

@@ -0,0 +1,92 @@
+package org.apache.lucene.analysis.core;
+
+/*
+ * 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 org.apache.lucene.analysis.BaseTokenStreamTestCase;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.standard.StandardTokenizer;
+import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
+import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
+import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
+import org.apache.lucene.util.English;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.Set;
+
+
+public class TestTypeTokenFilter extends BaseTokenStreamTestCase {
+
+  public void testTypeFilter() throws IOException {
+    StringReader reader = new StringReader("121 is palindrome, while 123 is not");
+    Set<String> stopTypes = asSet("<NUM>");
+    TokenStream stream = new TypeTokenFilter(true, new StandardTokenizer(TEST_VERSION_CURRENT, reader), stopTypes);
+    assertTokenStreamContents(stream, new String[]{"is", "palindrome", "while", "is", "not"});
+  }
+
+  /**
+   * Test Position increments applied by TypeTokenFilter with and without enabling this option.
+   */
+  public void testStopPositons() throws IOException {
+    StringBuilder sb = new StringBuilder();
+    for (int i = 10; i < 20; i++) {
+      if (i % 3 != 0) {
+        sb.append(i).append(" ");
+      } else {
+        String w = English.intToEnglish(i).trim();
+        sb.append(w).append(" ");
+      }
+    }
+    log(sb.toString());
+    String stopTypes[] = new String[]{"<NUM>"};
+    Set<String> stopSet = asSet(stopTypes);
+
+    // with increments
+    StringReader reader = new StringReader(sb.toString());
+    TypeTokenFilter typeTokenFilter = new TypeTokenFilter(true, new StandardTokenizer(TEST_VERSION_CURRENT, reader), stopSet);
+    testPositons(typeTokenFilter);
+
+    // without increments
+    reader = new StringReader(sb.toString());
+    typeTokenFilter = new TypeTokenFilter(false, new StandardTokenizer(TEST_VERSION_CURRENT, reader), stopSet);
+    testPositons(typeTokenFilter);
+
+  }
+
+  private void testPositons(TypeTokenFilter stpf) throws IOException {
+    TypeAttribute typeAtt = stpf.getAttribute(TypeAttribute.class);
+    CharTermAttribute termAttribute = stpf.getAttribute(CharTermAttribute.class);
+    PositionIncrementAttribute posIncrAtt = stpf.getAttribute(PositionIncrementAttribute.class);
+    stpf.reset();
+    boolean enablePositionIncrements = stpf.getEnablePositionIncrements();
+    while (stpf.incrementToken()) {
+      log("Token: " + termAttribute.toString() + ": " + typeAtt.type() + " - " + posIncrAtt.getPositionIncrement());
+      assertEquals("if position increment is enabled the positionIncrementAttribute value should be 3, otherwise 1",
+          posIncrAtt.getPositionIncrement(), enablePositionIncrements ? 3 : 1);
+    }
+    stpf.end();
+    stpf.close();
+  }
+
+  // print debug info depending on VERBOSE
+  private static void log(String s) {
+    if (VERBOSE) {
+      System.out.println(s);
+    }
+  }
+}