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.
*/
/**
* Decodes data which was encoded by {@link NOnesIntEncoder}. Uses a
* {@link FourFlagsIntDecoder} to perform the actual encoding and translates the
* values back as described in {@link NOnesIntEncoder}.
*
* @see NOnesIntEncoder
* @lucene.experimental
*/
public class NOnesIntDecoder extends FourFlagsIntDecoder {
/** Number of consecutive '1's to generate upon decoding a '2'. */
private int n;
private int onesCounter;
/**
* Constructs a decoder with a given N (Number of consecutive '1's which are
* translated into a single target value '2'.
*/
public NOnesIntDecoder(int n) {
this.n = n;
}
@Override
public long decode() throws IOException {
// If we read '2', we should return n '1's.
if (onesCounter > 0) {
--onesCounter;
return 1;
}
long decode = super.decode();
if (decode == 1) {
return 1;
}
if (decode == 2) {
onesCounter = n - 1;
return 1;
}
if (decode == 3) {
return 2;
}
return decode == EOS ? EOS : decode - 1;
}
@Override
public void reInit(InputStream in) {
super.reInit(in);
onesCounter = 0;
}
@Override
public String toString() {
return "NOnes (" + n + ") (" + super.toString() + ")";
}
}