add ngram factories: SOLR-199

git-svn-id: https://svn.apache.org/repos/asf/lucene/solr/trunk@540219 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -190,7 +190,10 @@ New Features
 31. SOLR-224: Adding a PhoneticFilterFactory that uses apache commons codec
     language encoders to build phonetically similar tokens.  This currently
     supports: DoubleMetaphone, Metaphone, Soundex, and RefinedSoundex (ryan)
-    
+
+32. SOLR-199: new n-gram tokenizers available via NGramTokenizerFactory 
+    and EdgeNGramTokenizerFactory. (Adam Hiatt via yonik)
+
 Changes in runtime behavior
  1. Highlighting using DisMax will only pick up terms from the main 
     user query, not boost or filter queries (klaas).

src/java/org/apache/solr/analysis/EdgeNGramTokenizerFactory.java

@@ -0,0 +1,55 @@
+package org.apache.solr.analysis;
+
+/**
+ * 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.ngram.EdgeNGramTokenizer;
+
+import java.io.Reader;
+import java.util.Map;
+
+/**
+ * Creates new instances of {@link EdgeNGramTokenizer}.
+ * @author Otis Gospodnetic
+ * @author Adam Hiatt
+ */
+public class EdgeNGramTokenizerFactory extends BaseTokenizerFactory {
+    private int maxGramSize = 0;
+
+    private int minGramSize = 0;
+
+    private String side;
+
+    public void init(Map<String, String> args) {
+        super.init(args);
+        String maxArg = args.get("maxGramSize");
+        maxGramSize = (maxArg != null ? Integer.parseInt(maxArg) : EdgeNGramTokenizer.DEFAULT_MAX_GRAM_SIZE);
+
+        String minArg = args.get("minGramSize");
+        minGramSize = (minArg != null ? Integer.parseInt(minArg) : EdgeNGramTokenizer.DEFAULT_MIN_GRAM_SIZE);
+
+        side = args.get("side");
+        if (side == null) {
+            side = EdgeNGramTokenizer.Side.FRONT.getLabel();
+        }
+    }
+
+    public TokenStream create(Reader input) {
+        return new EdgeNGramTokenizer(input, side, minGramSize, maxGramSize);
+    }
+}

src/java/org/apache/solr/analysis/NGramTokenizerFactory.java

@@ -0,0 +1,49 @@
+package org.apache.solr.analysis;
+
+/**
+ * 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.ngram.NGramTokenizer;
+
+import java.io.Reader;
+import java.util.Map;
+
+/**
+ * Creates new instances of {@link NGramTokenizer}.
+ * @author Otis Gospodnetic
+ * @author Adam Hiatt
+ */
+public class NGramTokenizerFactory extends BaseTokenizerFactory {
+    private int maxGramSize = 0;
+    private int minGramSize = 0;
+    
+    /** Initializes the n-gram min and max sizes and the side from which one should start tokenizing. */
+    public void init(Map<String, String> args) {
+        super.init(args);
+        String maxArg = args.get("maxGramSize");
+        maxGramSize = (maxArg != null ? Integer.parseInt(maxArg) : NGramTokenizer.DEFAULT_MAX_NGRAM_SIZE);
+
+        String minArg = args.get("minGramSize");
+        minGramSize = (minArg != null ? Integer.parseInt(minArg) : NGramTokenizer.DEFAULT_MIN_NGRAM_SIZE);
+    }
+
+    /** Creates the {@link TokenStream} of n-grams from the given {@link Reader}. */
+    public TokenStream create(Reader input) {
+        return new NGramTokenizer(input, minGramSize, maxGramSize);
+    }
+}