| /* Copyright 2004 The Apache Software Foundation |
| * |
| * Licensed 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. |
| */ |
| |
| package org.apache.xmlbeans.impl.common; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| import java.io.InputStream; |
| |
| |
| public abstract class PushedInputStream extends InputStream |
| { |
| private static int defaultBufferSize = 2048; |
| protected byte buf[]; |
| protected int writepos; |
| protected int readpos; |
| protected int markpos = -1; |
| protected int marklimit; |
| protected OutputStream outputStream = new InternalOutputStream(); |
| |
| /** |
| * Called when more bytes need to be written into this stream |
| * (as an OutputStream). |
| * |
| * This method must write at least one byte if the stream is |
| * not ended, and it must not write any bytes if the stream has |
| * already ended. |
| */ |
| protected abstract void fill(int requestedBytes) throws IOException; |
| |
| /** |
| * Returns the linked output stream. |
| * |
| * This is the output stream that must be written to whenever |
| * the fill method is called. |
| */ |
| public final OutputStream getOutputStream() |
| { |
| return outputStream; |
| } |
| |
| public PushedInputStream() |
| { |
| this(defaultBufferSize); |
| } |
| |
| public PushedInputStream(int size) |
| { |
| if (size < 0) |
| { |
| throw new IllegalArgumentException("Negative initial buffer size"); |
| } |
| buf = new byte[size]; |
| } |
| |
| /** |
| * Makes room for cb more bytes of data |
| */ |
| private void shift(int cb) |
| { |
| int savepos = readpos; |
| if (markpos > 0) |
| { |
| if (readpos - markpos > marklimit) |
| markpos = -1; |
| else |
| savepos = markpos; |
| } |
| |
| int size = writepos - savepos; |
| |
| if (savepos > 0 && buf.length - size >= cb && size <= cb) |
| { |
| System.arraycopy(buf, savepos, buf, 0, size); |
| } |
| else |
| { |
| int newcount = size + cb; |
| byte newbuf[] = new byte[Math.max(buf.length << 1, newcount)]; |
| System.arraycopy(buf, savepos, newbuf, 0, size); |
| buf = newbuf; |
| } |
| |
| if (savepos > 0) |
| { |
| readpos -= savepos; |
| if (markpos > 0) |
| markpos -= savepos; |
| writepos -= savepos; |
| } |
| } |
| |
| public synchronized int read() throws IOException |
| { |
| if (readpos >= writepos) |
| { |
| fill(1); |
| if (readpos >= writepos) |
| return -1; |
| } |
| return buf[readpos++] & 0xff; |
| } |
| |
| /** |
| * Read characters into a portion of an array, reading from the underlying |
| * stream at most once if necessary. |
| */ |
| public synchronized int read(byte[] b, int off, int len) throws IOException |
| { |
| int avail = writepos - readpos; |
| if (avail < len) |
| { |
| fill(len - avail); |
| avail = writepos - readpos; |
| if (avail <= 0) return -1; |
| } |
| int cnt = (avail < len) ? avail : len; |
| System.arraycopy(buf, readpos, b, off, cnt); |
| readpos += cnt; |
| return cnt; |
| } |
| |
| public synchronized long skip(long n) throws IOException |
| { |
| if (n <= 0) |
| return 0; |
| |
| long avail = writepos - readpos; |
| |
| if (avail < n) |
| { |
| // Fill in buffer to save bytes for reset |
| long req = n - avail; |
| if (req > Integer.MAX_VALUE) |
| req = Integer.MAX_VALUE; |
| fill((int)req); |
| avail = writepos - readpos; |
| if (avail <= 0) |
| return 0; |
| } |
| |
| long skipped = (avail < n) ? avail : n; |
| readpos += skipped; |
| return skipped; |
| } |
| |
| public synchronized int available() |
| { |
| return writepos - readpos; |
| } |
| |
| public synchronized void mark(int readlimit) |
| { |
| marklimit = readlimit; |
| markpos = readpos; |
| } |
| |
| public synchronized void reset() throws IOException |
| { |
| if (markpos < 0) |
| throw new IOException("Resetting to invalid mark"); |
| readpos = markpos; |
| } |
| |
| public boolean markSupported() |
| { |
| return true; |
| } |
| |
| private class InternalOutputStream extends OutputStream |
| { |
| public synchronized void write(int b) throws IOException |
| { |
| if (writepos + 1 > buf.length) |
| { |
| shift(1); |
| } |
| buf[writepos] = (byte)b; |
| writepos += 1; |
| } |
| |
| public synchronized void write(byte b[], int off, int len) |
| { |
| if ((off < 0) || (off > b.length) || (len < 0) || |
| ((off + len) > b.length) || ((off + len) < 0)) |
| throw new IndexOutOfBoundsException(); |
| else if (len == 0) |
| return; |
| |
| if (writepos + len > buf.length) |
| shift(len); |
| |
| System.arraycopy(b, off, buf, writepos, len); |
| writepos += len; |
| } |
| } |
| } |