125 lines
2.8 KiB
Java
125 lines
2.8 KiB
Java
/* Copyright (C) 1998, 1999 Cygnus Solutions
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This file is part of libgcj.
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This software is copyrighted work licensed under the terms of the
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Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
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details. */
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package java.io;
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/**
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* @author Warren Levy <warrenl@cygnus.com>
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* @date October 15, 1998.
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*/
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/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
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* "The Java Language Specification", ISBN 0-201-63451-1
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* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
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* Status: Believed complete and correct.
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*/
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public class PushbackInputStream extends FilterInputStream
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{
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/* Internal buffer array for data. */
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protected byte[] buf;
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/* The current position in the buffer. */
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protected int pos;
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public PushbackInputStream(InputStream in)
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{
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this(in, 1);
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}
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public PushbackInputStream(InputStream in, int size)
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{
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super(in);
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if (size < 0)
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throw new IllegalArgumentException();
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buf = new byte[size];
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pos = buf.length;
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}
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public int available() throws IOException
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{
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return pos + super.available();
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}
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public void close() throws IOException
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{
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buf = null;
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super.close();
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}
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public boolean markSupported()
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{
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return false;
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}
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public int read() throws IOException
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{
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if (pos < buf.length)
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return ((int) buf[pos++]) & 0xFF;
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return super.read();
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}
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public int read(byte[] b, int off, int len) throws IOException
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{
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if (off < 0 || len < 0 || off + len > b.length)
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throw new ArrayIndexOutOfBoundsException();
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int numBytes = Math.min(buf.length - pos, len);
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for (int i = 0; i < numBytes; i++)
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b[off++] = buf[pos++];
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// `off' was just incremented to include `numBytes', so we can
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// just pass ithere.
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return numBytes + super.read(b, off, len - numBytes);
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}
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public void unread(int b) throws IOException
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{
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if (pos <= 0)
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throw new IOException();
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buf[--pos] = (byte) b;
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}
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public void unread(byte[] b) throws IOException
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{
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unread(b, 0, b.length);
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}
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public void unread(byte[] b, int off, int len) throws IOException
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{
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if (pos < len)
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throw new IOException();
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// Note the order that these bytes are being added is the opposite
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// of what would be done if they were added to the buffer one at a time.
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// See the Java Class Libraries book p. 1390.
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System.arraycopy(b, off, buf, pos - len, len);
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// Don't put this into the arraycopy above, an exception might be thrown
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// and in that case we don't want to modify pos.
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pos -= len;
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}
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// JDK1.2
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public long skip(long n) throws IOException
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{
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final long origN = n;
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if (n > 0L)
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{
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int numread = (int) Math.min((long) (buf.length - pos), n);
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pos += numread;
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n -= numread;
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n -= super.skip(n);
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}
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return origN - n;
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}
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}
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