| /******************************************************************************* |
| * Copyright (c) 2004, 2008 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| * OBEO - fork for stand alone use in Acceleo |
| *******************************************************************************/ |
| package org.eclipse.acceleo.model.mtl.resource; |
| |
| // CHECKSTYLE:OFF |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * Forked from org.eclipse.core |
| * |
| * @since 3.1 |
| */ |
| public class LazyInputStream extends InputStream { |
| private int blockCapacity; |
| |
| byte[][] blocks = {}; |
| |
| private int bufferSize; |
| |
| private InputStream in; |
| |
| private int mark; |
| |
| private int offset; |
| |
| public LazyInputStream(InputStream in, int blockCapacity) { |
| this.in = in; |
| this.blockCapacity = blockCapacity; |
| } |
| |
| @Override |
| public int available() throws IOException { |
| try { |
| return bufferSize - offset + in.available(); |
| } catch (IOException ioe) { |
| throw new LowLevelIOException(ioe); |
| } |
| } |
| |
| private int computeBlockSize(int blockIndex) { |
| if (blockIndex < blocks.length - 1) { |
| return blockCapacity; |
| } |
| int blockSize = bufferSize % blockCapacity; |
| return blockSize == 0 ? blockCapacity : blockSize; |
| } |
| |
| private int copyFromBuffer(byte[] userBuffer, int userOffset, int needed) { |
| int copied = 0; |
| int current = offset / blockCapacity; |
| while ((needed - copied) > 0 && current < blocks.length) { |
| int blockSize = computeBlockSize(current); |
| int offsetInBlock = offset % blockCapacity; |
| int availableInBlock = blockSize - offsetInBlock; |
| int toCopy = Math.min(availableInBlock, needed - copied); |
| System.arraycopy(blocks[current], offsetInBlock, userBuffer, userOffset + copied, toCopy); |
| copied += toCopy; |
| current++; |
| offset += toCopy; |
| } |
| return copied; |
| } |
| |
| private void ensureAvailable(long bytesToRead) throws IOException { |
| int loadedBlockSize = blockCapacity; |
| while (bufferSize < offset + bytesToRead && loadedBlockSize == blockCapacity) { |
| try { |
| loadedBlockSize = loadBlock(); |
| } catch (IOException e) { |
| throw new LowLevelIOException(e); |
| } |
| bufferSize += loadedBlockSize; |
| } |
| } |
| |
| // for testing purposes |
| protected int getBlockCount() { |
| return blocks.length; |
| } |
| |
| // for testing purposes |
| protected int getBufferSize() { |
| return bufferSize; |
| } |
| |
| // for testing purposes |
| protected int getMark() { |
| return mark; |
| } |
| |
| // for testing purposes |
| protected int getOffset() { |
| return offset; |
| } |
| |
| public boolean isText() { |
| return false; |
| } |
| |
| private int loadBlock() throws IOException { |
| // read a block from the underlying stream |
| byte[] newBlock = new byte[blockCapacity]; |
| int readCount = in.read(newBlock); |
| if (readCount == -1) { |
| return 0; |
| } |
| // expand blocks array |
| byte[][] tmpBlocks = new byte[blocks.length + 1][]; |
| System.arraycopy(blocks, 0, tmpBlocks, 0, blocks.length); |
| blocks = tmpBlocks; |
| blocks[blocks.length - 1] = newBlock; |
| return readCount; |
| } |
| |
| @Override |
| public synchronized void mark(int readlimit) { |
| mark = offset; |
| } |
| |
| @Override |
| public boolean markSupported() { |
| return true; |
| } |
| |
| @Override |
| public int read() throws IOException { |
| ensureAvailable(1); |
| if (bufferSize <= offset) { |
| return -1; |
| } |
| int nextByte = 0xFF & blocks[offset / blockCapacity][offset % blockCapacity]; |
| offset++; |
| return nextByte; |
| } |
| |
| @Override |
| public int read(byte[] b) throws IOException { |
| return read(b, 0, b.length); |
| } |
| |
| @Override |
| public int read(byte[] b, int off, int len) throws IOException { |
| ensureAvailable(len); |
| int copied = copyFromBuffer(b, off, len); |
| return copied == 0 ? -1 : copied; |
| } |
| |
| @Override |
| public synchronized void reset() { |
| offset = mark; |
| } |
| |
| public void rewind() { |
| mark = 0; |
| offset = 0; |
| } |
| |
| @Override |
| public long skip(long toSkip) throws IOException { |
| if (toSkip <= 0) { |
| return 0; |
| } |
| ensureAvailable(toSkip); |
| long skipped = Math.min(toSkip, bufferSize - offset); |
| offset += skipped; |
| return skipped; |
| } |
| } |