pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / index / PayloadProcessorProvider.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/index/PayloadProcessorProvider.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/index/PayloadProcessorProvider.java
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+package org.apache.lucene.index;
+
+/**
+ * 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.IOException;
+
+import org.apache.lucene.store.Directory;
+
+/**
+ * Provides a {@link DirPayloadProcessor} to be used for a {@link Directory}.
+ * This allows using different {@link DirPayloadProcessor}s for different
+ * directories, for e.g. to perform different processing of payloads of
+ * different directories.
+ * <p>
+ * <b>NOTE:</b> to avoid processing payloads of certain directories, you can
+ * return <code>null</code> in {@link #getDirProcessor}.
+ * <p>
+ * <b>NOTE:</b> it is possible that the same {@link DirPayloadProcessor} will be
+ * requested for the same {@link Directory} concurrently. Therefore, to avoid
+ * concurrency issues you should return different instances for different
+ * threads. Usually, if your {@link DirPayloadProcessor} does not maintain state
+ * this is not a problem. The merge code ensures that the
+ * {@link DirPayloadProcessor} instance you return will be accessed by one
+ * thread to obtain the {@link PayloadProcessor}s for different terms.
+ * 
+ * @lucene.experimental
+ */
+public abstract class PayloadProcessorProvider {
+
+  /**
+   * Returns a {@link PayloadProcessor} for a given {@link Term} which allows
+   * processing the payloads of different terms differently. If you intent to
+   * process all your payloads the same way, then you can ignore the given term.
+   * <p>
+   * <b>NOTE:</b> if you protect your {@link DirPayloadProcessor} from
+   * concurrency issues, then you shouldn't worry about any such issues when
+   * {@link PayloadProcessor}s are requested for different terms.
+   */
+  public static abstract class DirPayloadProcessor {
+
+    /** Returns a {@link PayloadProcessor} for the given term. */
+    public abstract PayloadProcessor getProcessor(Term term) throws IOException;
+    
+  }
+
+  /**
+   * Processes the given payload. One should call {@link #payloadLength()} to
+   * get the length of the processed payload.
+   * 
+   * @lucene.experimental
+   */
+  public static abstract class PayloadProcessor {
+
+    /** Returns the length of the payload that was returned by {@link #processPayload}. */
+    public abstract int payloadLength() throws IOException;
+
+    /**
+     * Process the incoming payload and returns the resulting byte[]. Note that
+     * a new array might be allocated if the given array is not big enough. The
+     * length of the new payload data can be obtained via
+     * {@link #payloadLength()}.
+     */
+    public abstract byte[] processPayload(byte[] payload, int start, int length) throws IOException;
+
+  }
+
+  /**
+   * Returns a {@link DirPayloadProcessor} for the given {@link Directory},
+   * through which {@link PayloadProcessor}s can be obtained for each
+   * {@link Term}, or <code>null</code> if none should be used.
+   */
+  public abstract DirPayloadProcessor getDirProcessor(Directory dir) throws IOException;
+
+}