| /* Copyright (C) 1998, 1999, 2000 Free Software Foundation |
| |
| This file is part of libgcj. |
| |
| This software is copyrighted work licensed under the terms of the |
| Libgcj License. Please consult the file "LIBGCJ_LICENSE" for |
| details. */ |
| |
| package java.io; |
| |
| /** |
| * @author Warren Levy <warrenl@cygnus.com> |
| * @date October 15, 1998. |
| */ |
| /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 |
| * "The Java Language Specification", ISBN 0-201-63451-1 |
| * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. |
| * Status: Believed complete and correct. |
| */ |
| |
| public class PushbackInputStream extends FilterInputStream |
| { |
| /* Internal buffer array for data. */ |
| protected byte[] buf; |
| |
| /* The current position in the buffer. */ |
| protected int pos; |
| |
| public PushbackInputStream(InputStream in) |
| { |
| this(in, 1); |
| } |
| |
| public PushbackInputStream(InputStream in, int size) |
| { |
| super(in); |
| if (size < 0) |
| throw new IllegalArgumentException(); |
| buf = new byte[size]; |
| pos = buf.length; |
| } |
| |
| public int available() throws IOException |
| { |
| return pos + super.available(); |
| } |
| |
| public void close() throws IOException |
| { |
| buf = null; |
| super.close(); |
| } |
| |
| public boolean markSupported() |
| { |
| return false; |
| } |
| |
| public int read() throws IOException |
| { |
| if (pos < buf.length) |
| return ((int) buf[pos++]) & 0xFF; |
| |
| return super.read(); |
| } |
| |
| public int read(byte[] b, int off, int len) throws IOException |
| { |
| if (off < 0 || len < 0 || off + len > b.length) |
| throw new ArrayIndexOutOfBoundsException(); |
| |
| int numBytes = Math.min(buf.length - pos, len); |
| if (numBytes > 0) |
| { |
| System.arraycopy (buf, pos, b, off, numBytes); |
| pos += numBytes; |
| return numBytes; |
| } |
| |
| return super.read(b, off, len); |
| } |
| |
| public void unread(int b) throws IOException |
| { |
| if (pos <= 0) |
| throw new IOException(); |
| |
| buf[--pos] = (byte) b; |
| } |
| |
| public void unread(byte[] b) throws IOException |
| { |
| unread(b, 0, b.length); |
| } |
| |
| public void unread(byte[] b, int off, int len) throws IOException |
| { |
| if (pos < len) |
| throw new IOException(); |
| |
| // Note the order that these bytes are being added is the opposite |
| // of what would be done if they were added to the buffer one at a time. |
| // See the Java Class Libraries book p. 1390. |
| System.arraycopy(b, off, buf, pos - len, len); |
| |
| // Don't put this into the arraycopy above, an exception might be thrown |
| // and in that case we don't want to modify pos. |
| pos -= len; |
| } |
| |
| // JDK1.2 |
| public long skip(long n) throws IOException |
| { |
| final long origN = n; |
| |
| if (n > 0L) |
| { |
| int numread = (int) Math.min((long) (buf.length - pos), n); |
| pos += numread; |
| n -= numread; |
| n -= super.skip(n); |
| } |
| |
| return origN - n; |
| } |
| } |