lucene 4: add custom analyzer wrapper that supports overriding of getOffsetGap

src/main/java/org/apache/lucene/analysis/CustomAnalyzerWrapper.java

@@ -0,0 +1,85 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch 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.
+ */
+
+package org.apache.lucene.analysis;
+
+import java.io.Reader;
+
+/**
+ * Extension to {@link Analyzer} suitable for Analyzers which wrap
+ * other Analyzers.
+ * <p/>
+ * {@link #getWrappedAnalyzer(String)} allows the Analyzer
+ * to wrap multiple Analyzers which are selected on a per field basis.
+ * <p/>
+ * {@link #wrapComponents(String, Analyzer.TokenStreamComponents)} allows the
+ * TokenStreamComponents of the wrapped Analyzer to then be wrapped
+ * (such as adding a new {@link TokenFilter} to form new TokenStreamComponents.
+ */
+public abstract class CustomAnalyzerWrapper extends Analyzer {
+
+    /**
+     * Creates a new CustomAnalyzerWrapper.  Since the {@link Analyzer.ReuseStrategy} of
+     * the wrapped Analyzers are unknown, {@link Analyzer.PerFieldReuseStrategy} is assumed
+     */
+    protected CustomAnalyzerWrapper() {
+        super(new PerFieldReuseStrategy());
+    }
+
+    /**
+     * Retrieves the wrapped Analyzer appropriate for analyzing the field with
+     * the given name
+     *
+     * @param fieldName Name of the field which is to be analyzed
+     * @return Analyzer for the field with the given name.  Assumed to be non-null
+     */
+    protected abstract Analyzer getWrappedAnalyzer(String fieldName);
+
+    /**
+     * Wraps / alters the given TokenStreamComponents, taken from the wrapped
+     * Analyzer, to form new components.  It is through this method that new
+     * TokenFilters can be added by AnalyzerWrappers.
+     *
+     *
+     * @param fieldName Name of the field which is to be analyzed
+     * @param components TokenStreamComponents taken from the wrapped Analyzer
+     * @return Wrapped / altered TokenStreamComponents.
+     */
+    protected abstract TokenStreamComponents wrapComponents(String fieldName, TokenStreamComponents components);
+
+    @Override
+    protected final TokenStreamComponents createComponents(String fieldName, Reader aReader) {
+        return wrapComponents(fieldName, getWrappedAnalyzer(fieldName).createComponents(fieldName, aReader));
+    }
+
+    @Override
+    public int getPositionIncrementGap(String fieldName) {
+        return getWrappedAnalyzer(fieldName).getPositionIncrementGap(fieldName);
+    }
+
+    @Override
+    public int getOffsetGap(String fieldName) {
+        return getWrappedAnalyzer(fieldName).getOffsetGap(fieldName);
+    }
+
+    @Override
+    public final Reader initReader(String fieldName, Reader reader) {
+        return getWrappedAnalyzer(fieldName).initReader(fieldName, reader);
+    }
+}

src/main/java/org/elasticsearch/index/analysis/NamedAnalyzer.java

@@ -20,15 +20,13 @@
 package org.elasticsearch.index.analysis;
 
 import org.apache.lucene.analysis.Analyzer;
-import org.apache.lucene.analysis.AnalyzerWrapper;
-
-import java.io.Reader;
+import org.apache.lucene.analysis.CustomAnalyzerWrapper;
 
 /**
  * Named analyzer is an analyzer wrapper around an actual analyzer ({@link #analyzer} that is associated
  * with a name ({@link #name()}.
  */
-public class NamedAnalyzer extends AnalyzerWrapper {
+public class NamedAnalyzer extends CustomAnalyzerWrapper {
 
     private final String name;