--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/io/PushbackReader.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,281 @@
+/*
+ * Copyright 1996-2006 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.io;
+
+
+/**
+ * A character-stream reader that allows characters to be pushed back into the
+ * stream.
+ *
+ * @author Mark Reinhold
+ * @since JDK1.1
+ */
+
+public class PushbackReader extends FilterReader {
+
+ /** Pushback buffer */
+ private char[] buf;
+
+ /** Current position in buffer */
+ private int pos;
+
+ /**
+ * Creates a new pushback reader with a pushback buffer of the given size.
+ *
+ * @param in The reader from which characters will be read
+ * @param size The size of the pushback buffer
+ * @exception IllegalArgumentException if size is <= 0
+ */
+ public PushbackReader(Reader in, int size) {
+ super(in);
+ if (size <= 0) {
+ throw new IllegalArgumentException("size <= 0");
+ }
+ this.buf = new char[size];
+ this.pos = size;
+ }
+
+ /**
+ * Creates a new pushback reader with a one-character pushback buffer.
+ *
+ * @param in The reader from which characters will be read
+ */
+ public PushbackReader(Reader in) {
+ this(in, 1);
+ }
+
+ /** Checks to make sure that the stream has not been closed. */
+ private void ensureOpen() throws IOException {
+ if (buf == null)
+ throw new IOException("Stream closed");
+ }
+
+ /**
+ * Reads a single character.
+ *
+ * @return The character read, or -1 if the end of the stream has been
+ * reached
+ *
+ * @exception IOException If an I/O error occurs
+ */
+ public int read() throws IOException {
+ synchronized (lock) {
+ ensureOpen();
+ if (pos < buf.length)
+ return buf[pos++];
+ else
+ return super.read();
+ }
+ }
+
+ /**
+ * Reads characters into a portion of an array.
+ *
+ * @param cbuf Destination buffer
+ * @param off Offset at which to start writing characters
+ * @param len Maximum number of characters to read
+ *
+ * @return The number of characters read, or -1 if the end of the
+ * stream has been reached
+ *
+ * @exception IOException If an I/O error occurs
+ */
+ public int read(char cbuf[], int off, int len) throws IOException {
+ synchronized (lock) {
+ ensureOpen();
+ try {
+ if (len <= 0) {
+ if (len < 0) {
+ throw new IndexOutOfBoundsException();
+ } else if ((off < 0) || (off > cbuf.length)) {
+ throw new IndexOutOfBoundsException();
+ }
+ return 0;
+ }
+ int avail = buf.length - pos;
+ if (avail > 0) {
+ if (len < avail)
+ avail = len;
+ System.arraycopy(buf, pos, cbuf, off, avail);
+ pos += avail;
+ off += avail;
+ len -= avail;
+ }
+ if (len > 0) {
+ len = super.read(cbuf, off, len);
+ if (len == -1) {
+ return (avail == 0) ? -1 : avail;
+ }
+ return avail + len;
+ }
+ return avail;
+ } catch (ArrayIndexOutOfBoundsException e) {
+ throw new IndexOutOfBoundsException();
+ }
+ }
+ }
+
+ /**
+ * Pushes back a single character by copying it to the front of the
+ * pushback buffer. After this method returns, the next character to be read
+ * will have the value <code>(char)c</code>.
+ *
+ * @param c The int value representing a character to be pushed back
+ *
+ * @exception IOException If the pushback buffer is full,
+ * or if some other I/O error occurs
+ */
+ public void unread(int c) throws IOException {
+ synchronized (lock) {
+ ensureOpen();
+ if (pos == 0)
+ throw new IOException("Pushback buffer overflow");
+ buf[--pos] = (char) c;
+ }
+ }
+
+ /**
+ * Pushes back a portion of an array of characters by copying it to the
+ * front of the pushback buffer. After this method returns, the next
+ * character to be read will have the value <code>cbuf[off]</code>, the
+ * character after that will have the value <code>cbuf[off+1]</code>, and
+ * so forth.
+ *
+ * @param cbuf Character array
+ * @param off Offset of first character to push back
+ * @param len Number of characters to push back
+ *
+ * @exception IOException If there is insufficient room in the pushback
+ * buffer, or if some other I/O error occurs
+ */
+ public void unread(char cbuf[], int off, int len) throws IOException {
+ synchronized (lock) {
+ ensureOpen();
+ if (len > pos)
+ throw new IOException("Pushback buffer overflow");
+ pos -= len;
+ System.arraycopy(cbuf, off, buf, pos, len);
+ }
+ }
+
+ /**
+ * Pushes back an array of characters by copying it to the front of the
+ * pushback buffer. After this method returns, the next character to be
+ * read will have the value <code>cbuf[0]</code>, the character after that
+ * will have the value <code>cbuf[1]</code>, and so forth.
+ *
+ * @param cbuf Character array to push back
+ *
+ * @exception IOException If there is insufficient room in the pushback
+ * buffer, or if some other I/O error occurs
+ */
+ public void unread(char cbuf[]) throws IOException {
+ unread(cbuf, 0, cbuf.length);
+ }
+
+ /**
+ * Tells whether this stream is ready to be read.
+ *
+ * @exception IOException If an I/O error occurs
+ */
+ public boolean ready() throws IOException {
+ synchronized (lock) {
+ ensureOpen();
+ return (pos < buf.length) || super.ready();
+ }
+ }
+
+ /**
+ * Marks the present position in the stream. The <code>mark</code>
+ * for class <code>PushbackReader</code> always throws an exception.
+ *
+ * @exception IOException Always, since mark is not supported
+ */
+ public void mark(int readAheadLimit) throws IOException {
+ throw new IOException("mark/reset not supported");
+ }
+
+ /**
+ * Resets the stream. The <code>reset</code> method of
+ * <code>PushbackReader</code> always throws an exception.
+ *
+ * @exception IOException Always, since reset is not supported
+ */
+ public void reset() throws IOException {
+ throw new IOException("mark/reset not supported");
+ }
+
+ /**
+ * Tells whether this stream supports the mark() operation, which it does
+ * not.
+ */
+ public boolean markSupported() {
+ return false;
+ }
+
+ /**
+ * Closes the stream and releases any system resources associated with
+ * it. Once the stream has been closed, further read(),
+ * unread(), ready(), or skip() invocations will throw an IOException.
+ * Closing a previously closed stream has no effect.
+ *
+ * @exception IOException If an I/O error occurs
+ */
+ public void close() throws IOException {
+ super.close();
+ buf = null;
+ }
+
+ /**
+ * Skips characters. This method will block until some characters are
+ * available, an I/O error occurs, or the end of the stream is reached.
+ *
+ * @param n The number of characters to skip
+ *
+ * @return The number of characters actually skipped
+ *
+ * @exception IllegalArgumentException If <code>n</code> is negative.
+ * @exception IOException If an I/O error occurs
+ */
+ public long skip(long n) throws IOException {
+ if (n < 0L)
+ throw new IllegalArgumentException("skip value is negative");
+ synchronized (lock) {
+ ensureOpen();
+ int avail = buf.length - pos;
+ if (avail > 0) {
+ if (n <= avail) {
+ pos += n;
+ return n;
+ } else {
+ pos = buf.length;
+ n -= avail;
+ }
+ }
+ return avail + super.skip(n);
+ }
+ }
+}