--- /dev/null
+package org.apache.lucene.util.encoding;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * 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.
+ */
+
+/**
+ * An {@link IntDecoder} which wraps another {@link IntDecoder} and reverts the
+ * d-gap that was encoded by {@link DGapIntEncoder}. The wrapped decoder
+ * performs the actual decoding, while this class simply adds the decoded value
+ * to the previous value.
+ *
+ * @lucene.experimental
+ */
+public class DGapIntDecoder extends IntDecoder {
+
+ private final IntDecoder decoder;
+
+ private int prev = 0;
+
+ public DGapIntDecoder(IntDecoder decoder) {
+ this.decoder = decoder;
+ }
+
+ @Override
+ public long decode() throws IOException {
+ long decode = decoder.decode();
+ if (decode == EOS) {
+ return EOS;
+ }
+
+ return prev += decode;
+ }
+
+ @Override
+ public void reInit(InputStream in) {
+ decoder.reInit(in);
+ prev = 0;
+ }
+
+ @Override
+ public String toString() {
+ return "DGap (" + decoder.toString() + ")";
+ }
+
+}