269 lines
8.2 KiB
Java
269 lines
8.2 KiB
Java
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/*
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* Copyright (c) 1996, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.io;
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import java.nio.CharBuffer;
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import java.util.Objects;
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/**
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* This class implements a character buffer that can be used as a
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* character-input stream.
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*
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* @author Herb Jellinek
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* @since 1.1
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*/
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public class CharArrayReader extends Reader {
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/** The character buffer. */
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protected char[] buf;
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/** The current buffer position. */
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protected int pos;
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/** The position of mark in buffer. */
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protected int markedPos = 0;
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/**
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* The index of the end of this buffer. There is not valid
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* data at or beyond this index.
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*/
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protected int count;
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/**
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* Creates a CharArrayReader from the specified array of chars.
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* @param buf Input buffer (not copied)
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*/
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public CharArrayReader(char[] buf) {
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this.buf = buf;
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this.pos = 0;
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this.count = buf.length;
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}
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/**
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* Creates a CharArrayReader from the specified array of chars.
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*
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* <p> The resulting reader will start reading at the given
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* {@code offset}. The total number of {@code char} values that can be
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* read from this reader will be either {@code length} or
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* {@code buf.length-offset}, whichever is smaller.
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*
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* @throws IllegalArgumentException
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* If {@code offset} is negative or greater than
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* {@code buf.length}, or if {@code length} is negative, or if
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* the sum of these two values is negative.
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*
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* @param buf Input buffer (not copied)
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* @param offset Offset of the first char to read
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* @param length Number of chars to read
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*/
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public CharArrayReader(char[] buf, int offset, int length) {
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if ((offset < 0) || (offset > buf.length) || (length < 0) ||
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((offset + length) < 0)) {
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throw new IllegalArgumentException();
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}
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this.buf = buf;
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this.pos = offset;
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this.count = Math.min(offset + length, buf.length);
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this.markedPos = offset;
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}
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/** Checks to make sure that the stream has not been closed */
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private void ensureOpen() throws IOException {
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if (buf == null)
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throw new IOException("Stream closed");
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}
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/**
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* Reads a single character.
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*
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* @throws IOException If an I/O error occurs
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*/
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public int read() throws IOException {
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synchronized (lock) {
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ensureOpen();
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if (pos >= count)
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return -1;
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else
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return buf[pos++];
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}
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}
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/**
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* Reads characters into a portion of an array.
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*
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* <p> If {@code len} is zero, then no characters are read and {@code 0} is
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* returned; otherwise, there is an attempt to read at least one character.
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* If no character is available because the stream is at its end, the value
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* {@code -1} is returned; otherwise, at least one character is read and
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* stored into {@code cbuf}.
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*
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* @param cbuf {@inheritDoc}
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* @param off {@inheritDoc}
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* @param len {@inheritDoc}
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*
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* @return {@inheritDoc}
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*
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* @throws IndexOutOfBoundsException {@inheritDoc}
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* @throws IOException {@inheritDoc}
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*/
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public int read(char[] cbuf, int off, int len) throws IOException {
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synchronized (lock) {
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ensureOpen();
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Objects.checkFromIndexSize(off, len, cbuf.length);
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if (len == 0) {
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return 0;
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}
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if (pos >= count) {
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return -1;
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}
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int avail = count - pos;
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if (len > avail) {
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len = avail;
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}
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if (len <= 0) {
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return 0;
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}
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System.arraycopy(buf, pos, cbuf, off, len);
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pos += len;
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return len;
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}
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}
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@Override
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public int read(CharBuffer target) throws IOException {
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synchronized (lock) {
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ensureOpen();
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if (pos >= count) {
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return -1;
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}
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int avail = count - pos;
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int len = Math.min(avail, target.remaining());
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target.put(buf, pos, len);
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pos += len;
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return len;
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}
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}
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/**
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* Skips characters. If the stream is already at its end before this method
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* is invoked, then no characters are skipped and zero is returned.
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*
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* <p>The {@code n} parameter may be negative, even though the
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* {@code skip} method of the {@link Reader} superclass throws
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* an exception in this case. If {@code n} is negative, then
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* this method does nothing and returns {@code 0}.
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*
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* @param n {@inheritDoc}
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*
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* @return {@inheritDoc}
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*
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* @throws IOException {@inheritDoc}
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*/
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public long skip(long n) throws IOException {
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synchronized (lock) {
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ensureOpen();
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long avail = count - pos;
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if (n > avail) {
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n = avail;
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}
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if (n < 0) {
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return 0;
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}
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pos += n;
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return n;
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}
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}
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/**
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* Tells whether this stream is ready to be read. Character-array readers
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* are always ready to be read.
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*
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* @throws IOException If an I/O error occurs
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*/
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public boolean ready() throws IOException {
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synchronized (lock) {
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ensureOpen();
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return (count - pos) > 0;
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}
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}
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/**
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* Tells whether this stream supports the mark() operation, which it does.
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*/
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public boolean markSupported() {
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return true;
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}
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/**
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* Marks the present position in the stream. Subsequent calls to reset()
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* will reposition the stream to this point.
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*
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* @param readAheadLimit Limit on the number of characters that may be
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* read while still preserving the mark. Because
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* the stream's input comes from a character array,
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* there is no actual limit; hence this argument is
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* ignored.
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*
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* @throws IOException If an I/O error occurs
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*/
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public void mark(int readAheadLimit) throws IOException {
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synchronized (lock) {
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ensureOpen();
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markedPos = pos;
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}
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}
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/**
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* Resets the stream to the most recent mark, or to the beginning if it has
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* never been marked.
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*
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* @throws IOException If an I/O error occurs
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*/
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public void reset() throws IOException {
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synchronized (lock) {
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ensureOpen();
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pos = markedPos;
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}
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}
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/**
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* Closes the stream and releases any system resources associated with
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* it. Once the stream has been closed, further read(), ready(),
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* mark(), reset(), or skip() invocations will throw an IOException.
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* Closing a previously closed stream has no effect. This method will block
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* while there is another thread blocking on the reader.
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*/
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public void close() {
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synchronized (lock) {
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buf = null;
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}
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}
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}
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