jtulach@147: /*
jtulach@147:  * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved.
jtulach@147:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jtulach@147:  *
jtulach@147:  * This code is free software; you can redistribute it and/or modify it
jtulach@147:  * under the terms of the GNU General Public License version 2 only, as
jtulach@147:  * published by the Free Software Foundation.  Oracle designates this
jtulach@147:  * particular file as subject to the "Classpath" exception as provided
jtulach@147:  * by Oracle in the LICENSE file that accompanied this code.
jtulach@147:  *
jtulach@147:  * This code is distributed in the hope that it will be useful, but WITHOUT
jtulach@147:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jtulach@147:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jtulach@147:  * version 2 for more details (a copy is included in the LICENSE file that
jtulach@147:  * accompanied this code).
jtulach@147:  *
jtulach@147:  * You should have received a copy of the GNU General Public License version
jtulach@147:  * 2 along with this work; if not, write to the Free Software Foundation,
jtulach@147:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jtulach@147:  *
jtulach@147:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jtulach@147:  * or visit www.oracle.com if you need additional information or have any
jtulach@147:  * questions.
jtulach@147:  */
jtulach@147: 
jtulach@147: package java.io;
jtulach@147: 
jaroslav@560: import org.apidesign.bck2brwsr.emul.lang.System;
jaroslav@560: 
jtulach@147: /**
jtulach@147:  * A <code>PushbackInputStream</code> adds
jtulach@147:  * functionality to another input stream, namely
jtulach@147:  * the  ability to "push back" or "unread"
jtulach@147:  * one byte. This is useful in situations where
jtulach@147:  * it is  convenient for a fragment of code
jtulach@147:  * to read an indefinite number of data bytes
jtulach@147:  * that  are delimited by a particular byte
jtulach@147:  * value; after reading the terminating byte,
jtulach@147:  * the  code fragment can "unread" it, so that
jtulach@147:  * the next read operation on the input stream
jtulach@147:  * will reread the byte that was pushed back.
jtulach@147:  * For example, bytes representing the  characters
jtulach@147:  * constituting an identifier might be terminated
jtulach@147:  * by a byte representing an  operator character;
jtulach@147:  * a method whose job is to read just an identifier
jtulach@147:  * can read until it  sees the operator and
jtulach@147:  * then push the operator back to be re-read.
jtulach@147:  *
jtulach@147:  * @author  David Connelly
jtulach@147:  * @author  Jonathan Payne
jtulach@147:  * @since   JDK1.0
jtulach@147:  */
jtulach@147: public
jtulach@147: class PushbackInputStream extends FilterInputStream {
jtulach@147:     /**
jtulach@147:      * The pushback buffer.
jtulach@147:      * @since   JDK1.1
jtulach@147:      */
jtulach@147:     protected byte[] buf;
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * The position within the pushback buffer from which the next byte will
jtulach@147:      * be read.  When the buffer is empty, <code>pos</code> is equal to
jtulach@147:      * <code>buf.length</code>; when the buffer is full, <code>pos</code> is
jtulach@147:      * equal to zero.
jtulach@147:      *
jtulach@147:      * @since   JDK1.1
jtulach@147:      */
jtulach@147:     protected int pos;
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Check to make sure that this stream has not been closed
jtulach@147:      */
jtulach@147:     private void ensureOpen() throws IOException {
jtulach@147:         if (in == null)
jtulach@147:             throw new IOException("Stream closed");
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Creates a <code>PushbackInputStream</code>
jtulach@147:      * with a pushback buffer of the specified <code>size</code>,
jtulach@147:      * and saves its  argument, the input stream
jtulach@147:      * <code>in</code>, for later use. Initially,
jtulach@147:      * there is no pushed-back byte  (the field
jtulach@147:      * <code>pushBack</code> is initialized to
jtulach@147:      * <code>-1</code>).
jtulach@147:      *
jtulach@147:      * @param  in    the input stream from which bytes will be read.
jtulach@147:      * @param  size  the size of the pushback buffer.
jtulach@147:      * @exception IllegalArgumentException if size is <= 0
jtulach@147:      * @since  JDK1.1
jtulach@147:      */
jtulach@147:     public PushbackInputStream(InputStream in, int size) {
jtulach@147:         super(in);
jtulach@147:         if (size <= 0) {
jtulach@147:             throw new IllegalArgumentException("size <= 0");
jtulach@147:         }
jtulach@147:         this.buf = new byte[size];
jtulach@147:         this.pos = size;
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Creates a <code>PushbackInputStream</code>
jtulach@147:      * and saves its  argument, the input stream
jtulach@147:      * <code>in</code>, for later use. Initially,
jtulach@147:      * there is no pushed-back byte  (the field
jtulach@147:      * <code>pushBack</code> is initialized to
jtulach@147:      * <code>-1</code>).
jtulach@147:      *
jtulach@147:      * @param   in   the input stream from which bytes will be read.
jtulach@147:      */
jtulach@147:     public PushbackInputStream(InputStream in) {
jtulach@147:         this(in, 1);
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Reads the next byte of data from this input stream. The value
jtulach@147:      * byte is returned as an <code>int</code> in the range
jtulach@147:      * <code>0</code> to <code>255</code>. If no byte is available
jtulach@147:      * because the end of the stream has been reached, the value
jtulach@147:      * <code>-1</code> is returned. This method blocks until input data
jtulach@147:      * is available, the end of the stream is detected, or an exception
jtulach@147:      * is thrown.
jtulach@147:      *
jtulach@147:      * <p> This method returns the most recently pushed-back byte, if there is
jtulach@147:      * one, and otherwise calls the <code>read</code> method of its underlying
jtulach@147:      * input stream and returns whatever value that method returns.
jtulach@147:      *
jtulach@147:      * @return     the next byte of data, or <code>-1</code> if the end of the
jtulach@147:      *             stream has been reached.
jtulach@147:      * @exception  IOException  if this input stream has been closed by
jtulach@147:      *             invoking its {@link #close()} method,
jtulach@147:      *             or an I/O error occurs.
jtulach@147:      * @see        java.io.InputStream#read()
jtulach@147:      */
jtulach@147:     public int read() throws IOException {
jtulach@147:         ensureOpen();
jtulach@147:         if (pos < buf.length) {
jtulach@147:             return buf[pos++] & 0xff;
jtulach@147:         }
jtulach@147:         return super.read();
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Reads up to <code>len</code> bytes of data from this input stream into
jtulach@147:      * an array of bytes.  This method first reads any pushed-back bytes; after
jtulach@147:      * that, if fewer than <code>len</code> bytes have been read then it
jtulach@147:      * reads from the underlying input stream. If <code>len</code> is not zero, the method
jtulach@147:      * blocks until at least 1 byte of input is available; otherwise, no
jtulach@147:      * bytes are read and <code>0</code> is returned.
jtulach@147:      *
jtulach@147:      * @param      b     the buffer into which the data is read.
jtulach@147:      * @param      off   the start offset in the destination array <code>b</code>
jtulach@147:      * @param      len   the maximum number of bytes read.
jtulach@147:      * @return     the total number of bytes read into the buffer, or
jtulach@147:      *             <code>-1</code> if there is no more data because the end of
jtulach@147:      *             the stream has been reached.
jtulach@147:      * @exception  NullPointerException If <code>b</code> is <code>null</code>.
jtulach@147:      * @exception  IndexOutOfBoundsException If <code>off</code> is negative,
jtulach@147:      * <code>len</code> is negative, or <code>len</code> is greater than
jtulach@147:      * <code>b.length - off</code>
jtulach@147:      * @exception  IOException  if this input stream has been closed by
jtulach@147:      *             invoking its {@link #close()} method,
jtulach@147:      *             or an I/O error occurs.
jtulach@147:      * @see        java.io.InputStream#read(byte[], int, int)
jtulach@147:      */
jtulach@147:     public int read(byte[] b, int off, int len) throws IOException {
jtulach@147:         ensureOpen();
jtulach@147:         if (b == null) {
jtulach@147:             throw new NullPointerException();
jtulach@147:         } else if (off < 0 || len < 0 || len > b.length - off) {
jtulach@147:             throw new IndexOutOfBoundsException();
jtulach@147:         } else if (len == 0) {
jtulach@147:             return 0;
jtulach@147:         }
jtulach@147: 
jtulach@147:         int avail = buf.length - pos;
jtulach@147:         if (avail > 0) {
jtulach@147:             if (len < avail) {
jtulach@147:                 avail = len;
jtulach@147:             }
jaroslav@560:             System.arraycopy(buf, pos, b, off, avail);
jtulach@147:             pos += avail;
jtulach@147:             off += avail;
jtulach@147:             len -= avail;
jtulach@147:         }
jtulach@147:         if (len > 0) {
jtulach@147:             len = super.read(b, off, len);
jtulach@147:             if (len == -1) {
jtulach@147:                 return avail == 0 ? -1 : avail;
jtulach@147:             }
jtulach@147:             return avail + len;
jtulach@147:         }
jtulach@147:         return avail;
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Pushes back a byte by copying it to the front of the pushback buffer.
jtulach@147:      * After this method returns, the next byte to be read will have the value
jtulach@147:      * <code>(byte)b</code>.
jtulach@147:      *
jtulach@147:      * @param      b   the <code>int</code> value whose low-order
jtulach@147:      *                  byte is to be pushed back.
jtulach@147:      * @exception IOException If there is not enough room in the pushback
jtulach@147:      *            buffer for the byte, or this input stream has been closed by
jtulach@147:      *            invoking its {@link #close()} method.
jtulach@147:      */
jtulach@147:     public void unread(int b) throws IOException {
jtulach@147:         ensureOpen();
jtulach@147:         if (pos == 0) {
jtulach@147:             throw new IOException("Push back buffer is full");
jtulach@147:         }
jtulach@147:         buf[--pos] = (byte)b;
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Pushes back a portion of an array of bytes by copying it to the front
jtulach@147:      * of the pushback buffer.  After this method returns, the next byte to be
jtulach@147:      * read will have the value <code>b[off]</code>, the byte after that will
jtulach@147:      * have the value <code>b[off+1]</code>, and so forth.
jtulach@147:      *
jtulach@147:      * @param b the byte array to push back.
jtulach@147:      * @param off the start offset of the data.
jtulach@147:      * @param len the number of bytes to push back.
jtulach@147:      * @exception IOException If there is not enough room in the pushback
jtulach@147:      *            buffer for the specified number of bytes,
jtulach@147:      *            or this input stream has been closed by
jtulach@147:      *            invoking its {@link #close()} method.
jtulach@147:      * @since     JDK1.1
jtulach@147:      */
jtulach@147:     public void unread(byte[] b, int off, int len) throws IOException {
jtulach@147:         ensureOpen();
jtulach@147:         if (len > pos) {
jtulach@147:             throw new IOException("Push back buffer is full");
jtulach@147:         }
jtulach@147:         pos -= len;
jaroslav@560:         System.arraycopy(b, off, buf, pos, len);
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Pushes back an array of bytes by copying it to the front of the
jtulach@147:      * pushback buffer.  After this method returns, the next byte to be read
jtulach@147:      * will have the value <code>b[0]</code>, the byte after that will have the
jtulach@147:      * value <code>b[1]</code>, and so forth.
jtulach@147:      *
jtulach@147:      * @param b the byte array to push back
jtulach@147:      * @exception IOException If there is not enough room in the pushback
jtulach@147:      *            buffer for the specified number of bytes,
jtulach@147:      *            or this input stream has been closed by
jtulach@147:      *            invoking its {@link #close()} method.
jtulach@147:      * @since     JDK1.1
jtulach@147:      */
jtulach@147:     public void unread(byte[] b) throws IOException {
jtulach@147:         unread(b, 0, b.length);
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Returns an estimate of the number of bytes that can be read (or
jtulach@147:      * skipped over) from this input stream without blocking by the next
jtulach@147:      * invocation of a method for this input stream. The next invocation might be
jtulach@147:      * the same thread or another thread.  A single read or skip of this
jtulach@147:      * many bytes will not block, but may read or skip fewer bytes.
jtulach@147:      *
jtulach@147:      * <p> The method returns the sum of the number of bytes that have been
jtulach@147:      * pushed back and the value returned by {@link
jtulach@147:      * java.io.FilterInputStream#available available}.
jtulach@147:      *
jtulach@147:      * @return     the number of bytes that can be read (or skipped over) from
jtulach@147:      *             the input stream without blocking.
jtulach@147:      * @exception  IOException  if this input stream has been closed by
jtulach@147:      *             invoking its {@link #close()} method,
jtulach@147:      *             or an I/O error occurs.
jtulach@147:      * @see        java.io.FilterInputStream#in
jtulach@147:      * @see        java.io.InputStream#available()
jtulach@147:      */
jtulach@147:     public int available() throws IOException {
jtulach@147:         ensureOpen();
jtulach@147:         int n = buf.length - pos;
jtulach@147:         int avail = super.available();
jtulach@147:         return n > (Integer.MAX_VALUE - avail)
jtulach@147:                     ? Integer.MAX_VALUE
jtulach@147:                     : n + avail;
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Skips over and discards <code>n</code> bytes of data from this
jtulach@147:      * input stream. The <code>skip</code> method may, for a variety of
jtulach@147:      * reasons, end up skipping over some smaller number of bytes,
jtulach@147:      * possibly zero.  If <code>n</code> is negative, no bytes are skipped.
jtulach@147:      *
jtulach@147:      * <p> The <code>skip</code> method of <code>PushbackInputStream</code>
jtulach@147:      * first skips over the bytes in the pushback buffer, if any.  It then
jtulach@147:      * calls the <code>skip</code> method of the underlying input stream if
jtulach@147:      * more bytes need to be skipped.  The actual number of bytes skipped
jtulach@147:      * is returned.
jtulach@147:      *
jtulach@147:      * @param      n  {@inheritDoc}
jtulach@147:      * @return     {@inheritDoc}
jtulach@147:      * @exception  IOException  if the stream does not support seek,
jtulach@147:      *            or the stream has been closed by
jtulach@147:      *            invoking its {@link #close()} method,
jtulach@147:      *            or an I/O error occurs.
jtulach@147:      * @see        java.io.FilterInputStream#in
jtulach@147:      * @see        java.io.InputStream#skip(long n)
jtulach@147:      * @since      1.2
jtulach@147:      */
jtulach@147:     public long skip(long n) throws IOException {
jtulach@147:         ensureOpen();
jtulach@147:         if (n <= 0) {
jtulach@147:             return 0;
jtulach@147:         }
jtulach@147: 
jtulach@147:         long pskip = buf.length - pos;
jtulach@147:         if (pskip > 0) {
jtulach@147:             if (n < pskip) {
jtulach@147:                 pskip = n;
jtulach@147:             }
jtulach@147:             pos += pskip;
jtulach@147:             n -= pskip;
jtulach@147:         }
jtulach@147:         if (n > 0) {
jtulach@147:             pskip += super.skip(n);
jtulach@147:         }
jtulach@147:         return pskip;
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Tests if this input stream supports the <code>mark</code> and
jtulach@147:      * <code>reset</code> methods, which it does not.
jtulach@147:      *
jtulach@147:      * @return   <code>false</code>, since this class does not support the
jtulach@147:      *           <code>mark</code> and <code>reset</code> methods.
jtulach@147:      * @see     java.io.InputStream#mark(int)
jtulach@147:      * @see     java.io.InputStream#reset()
jtulach@147:      */
jtulach@147:     public boolean markSupported() {
jtulach@147:         return false;
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Marks the current position in this input stream.
jtulach@147:      *
jtulach@147:      * <p> The <code>mark</code> method of <code>PushbackInputStream</code>
jtulach@147:      * does nothing.
jtulach@147:      *
jtulach@147:      * @param   readlimit   the maximum limit of bytes that can be read before
jtulach@147:      *                      the mark position becomes invalid.
jtulach@147:      * @see     java.io.InputStream#reset()
jtulach@147:      */
jtulach@147:     public synchronized void mark(int readlimit) {
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Repositions this stream to the position at the time the
jtulach@147:      * <code>mark</code> method was last called on this input stream.
jtulach@147:      *
jtulach@147:      * <p> The method <code>reset</code> for class
jtulach@147:      * <code>PushbackInputStream</code> does nothing except throw an
jtulach@147:      * <code>IOException</code>.
jtulach@147:      *
jtulach@147:      * @exception  IOException  if this method is invoked.
jtulach@147:      * @see     java.io.InputStream#mark(int)
jtulach@147:      * @see     java.io.IOException
jtulach@147:      */
jtulach@147:     public synchronized void reset() throws IOException {
jtulach@147:         throw new IOException("mark/reset not supported");
jtulach@147:     }
jtulach@147: 
jtulach@147:     /**
jtulach@147:      * Closes this input stream and releases any system resources
jtulach@147:      * associated with the stream.
jtulach@147:      * Once the stream has been closed, further read(), unread(),
jtulach@147:      * available(), reset(), or skip() invocations will throw an IOException.
jtulach@147:      * Closing a previously closed stream has no effect.
jtulach@147:      *
jtulach@147:      * @exception  IOException  if an I/O error occurs.
jtulach@147:      */
jtulach@147:     public synchronized void close() throws IOException {
jtulach@147:         if (in == null)
jtulach@147:             return;
jtulach@147:         in.close();
jtulach@147:         in = null;
jtulach@147:         buf = null;
jtulach@147:     }
jtulach@147: }