/*
 * Copyright 2000-2016 JetBrains s.r.o.
 *
 * Licensed 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 com.intellij.util.indexing;

import com.intellij.util.io.DataExternalizer;
import com.intellij.util.io.KeyDescriptor;
import org.jetbrains.annotations.NotNull;

/**
 * @author Eugene Zhuravlev
 * V class MUST have equals / hashcode properly defined!!!
 */
public abstract class IndexExtension<K, V, I> {
  @NotNull
  public abstract IndexId<K, V> getName();

  @NotNull
  public abstract DataIndexer<K, V, I> getIndexer();

  @NotNull
  public abstract KeyDescriptor<K> getKeyDescriptor();

  @NotNull
  public abstract DataExternalizer<V> getValueExternalizer();

  public abstract int getVersion();
}

@@ -775,91 +775,273 @@
 %0A * 
-@author Eugene Zhuravlev%0A * V class MUST have equals / hashcode properly defined!!!
+Represents index data format specification, namely%0A * serialization format for keys & values,%0A * and a mapping from input to indexing data.%0A *%0A * To create index corresponding to any extension%0A * one could use %7B@link com.intellij.util.indexing.impl.MapReduceIndex%7D.
 %0A */
@@ -1083,17 +1083,94 @@
 on%3CK
+ey
 , V
-, I%3E %7B
+alue, Input%3E %7B%0A  /**%0A   * @return unique name identifier of index extension%0A   */
 %0A  @
@@ -1204,19 +1204,25 @@
 ndexId%3CK
+ey
 , V
+alue
 %3E getNam
@@ -1223,24 +1223,136 @@
 getName();%0A%0A
+  /**%0A   * @return indexer which determines the procedure how input should be transformed to indexed data%0A   */%0A
   @NotNull%0A 
@@ -1385,14 +1385,24 @@
 er%3CK
+ey
 , V
-, I
+alue, Input
 %3E ge
@@ -1458,16 +1458,18 @@
 riptor%3CK
+ey
 %3E getKey
@@ -1530,16 +1530,20 @@
 alizer%3CV
+alue
 %3E getVal

add javadoc to IndexExtension