| /******************************************************************************* |
| * Copyright (c) 2004, 2005 IBM Corporation and others. |
| * |
| * This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License 2.0 |
| * which accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.core.internal.content; |
| |
| import java.io.IOException; |
| import java.io.Reader; |
| |
| public class LazyReader extends Reader implements ILazySource { |
| private int blockCapacity; |
| char[][] blocks = {}; |
| private int bufferSize; |
| private Reader in; |
| private int mark; |
| private int offset; |
| |
| public LazyReader(Reader in, int blockCapacity) { |
| this.in = in; |
| this.blockCapacity = blockCapacity; |
| } |
| |
| @Override |
| public void close() { |
| // we don't close the underlying stream |
| } |
| |
| private int computeBlockSize(int blockIndex) { |
| if (blockIndex < blocks.length - 1) |
| return blockCapacity; |
| int blockSize = bufferSize % blockCapacity; |
| return blockSize == 0 ? blockCapacity : blockSize; |
| } |
| |
| private int copyFromBuffer(char[] 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 charsToRead) throws IOException { |
| int loadedBlockSize = blockCapacity; |
| while (bufferSize < offset + charsToRead && loadedBlockSize == blockCapacity) { |
| try { |
| loadedBlockSize = loadBlock(); |
| } catch (IOException ioe) { |
| throw new LowLevelIOException(ioe); |
| } |
| 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; |
| } |
| |
| @Override |
| public boolean isText() { |
| return true; |
| } |
| |
| private int loadBlock() throws IOException { |
| // read a block from the underlying stream |
| char[] newBlock = new char[blockCapacity]; |
| int readCount = in.read(newBlock); |
| if (readCount == -1) |
| return 0; |
| // expand blocks array |
| char[][] tmpBlocks = new char[blocks.length + 1][]; |
| System.arraycopy(blocks, 0, tmpBlocks, 0, blocks.length); |
| blocks = tmpBlocks; |
| blocks[blocks.length - 1] = newBlock; |
| return readCount; |
| } |
| |
| @Override |
| public 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; |
| char nextChar = blocks[offset / blockCapacity][offset % blockCapacity]; |
| offset++; |
| return nextChar; |
| } |
| |
| @Override |
| public int read(char[] c) throws IOException { |
| return read(c, 0, c.length); |
| } |
| |
| @Override |
| public int read(char[] c, int off, int len) throws IOException { |
| ensureAvailable(len); |
| int copied = copyFromBuffer(c, off, len); |
| return copied == 0 ? -1 : copied; |
| } |
| |
| @Override |
| public boolean ready() throws IOException { |
| try { |
| return (bufferSize - offset) > 0 || in.ready(); |
| } catch (IOException ioe) { |
| throw new LowLevelIOException(ioe); |
| } |
| } |
| |
| @Override |
| public void reset() { |
| offset = mark; |
| } |
| |
| @Override |
| 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; |
| } |
| } |