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package org.apache.lucene.util;
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import java.io.ByteArrayInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* This class, much like {@link ByteArrayInputStream} uses a given buffer as a
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* source of an InputStream. Unlike ByteArrayInputStream, this class does not
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* "waste" memory by creating a local copy of the given buffer, but rather uses
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* the given buffer as is. Hence the name Unsafe. While using this class one
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* should remember that the byte[] buffer memory is shared and might be changed
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* For reuse-ability, a call for {@link #reInit(byte[])} can be called, and
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* initialize the stream with a new buffer.
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* @lucene.experimental
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public class UnsafeByteArrayInputStream extends InputStream {
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private byte[] buffer;
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private int markIndex;
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private int upperLimit;
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* Creates a new instance by not using any byte[] up front. If you use this
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* constructor, you MUST call either of the {@link #reInit(byte[]) reInit}
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* methods before you consume any byte from this instance.<br>
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* This constructor is for convenience purposes only, so that if one does not
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* have the byte[] at the moment of creation, one is not forced to pass a
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* <code>new byte[0]</code> or something. Obviously in that case, one will
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* call either {@link #reInit(byte[]) reInit} methods before using the class.
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public UnsafeByteArrayInputStream() {
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markIndex = upperLimit = index = 0;
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* Creates an UnsafeByteArrayInputStream which uses a given byte array as
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* the source of the stream. Default range is [0 , buffer.length)
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* byte array used as the source of this stream
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public UnsafeByteArrayInputStream(byte[] buffer) {
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reInit(buffer, 0, buffer.length);
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* Creates an UnsafeByteArrayInputStream which uses a given byte array as
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* the source of the stream, at the specific range: [startPos, endPos)
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* byte array used as the source of this stream
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* first index (inclusive) to the data lying in the given buffer
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* an index (exclusive) where the data ends. data @
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* buffer[endPos] will never be read
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public UnsafeByteArrayInputStream(byte[] buffer, int startPos, int endPos) {
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reInit(buffer, startPos, endPos);
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public void mark(int readlimit) {
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public boolean markSupported() {
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* Initialize the stream with a given buffer, using the default limits of
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* byte array used as the source of this stream
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public void reInit(byte[] buffer) {
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reInit(buffer, 0, buffer.length);
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* Initialize the stream with a given byte array as the source of the
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* stream, at the specific range: [startPos, endPos)
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* byte array used as the source of this stream
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* first index (inclusive) to the data lying in the given buffer
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* an index (exclusive) where the data ends. data @
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* buffer[endPos] will never be read
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public void reInit(byte[] buffer, int startPos, int endPos) {
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this.buffer = buffer;
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markIndex = startPos;
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public int available() throws IOException {
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return upperLimit - index;
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* Read a byte. Data returned as an integer [0,255] If end of stream
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* reached, returns -1
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public int read() throws IOException {
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return index < upperLimit ? buffer[index++] & 0xff : -1;
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* Resets the stream back to its original state. Basically - moving the
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* index back to start position.
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public void reset() throws IOException {