150 lines
4.3 KiB
Java
150 lines
4.3 KiB
Java
/* gnu/regexp/CharIndexedInputStream.java
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Copyright (C) 1998-2001, 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.regexp;
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import java.io.BufferedInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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// TODO: move(x) shouldn't rely on calling next() x times
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class CharIndexedInputStream implements CharIndexed {
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private static final int BUFFER_INCREMENT = 1024;
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private static final int UNKNOWN = Integer.MAX_VALUE; // value for end
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private BufferedInputStream br;
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// so that we don't try to reset() right away
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private int index = -1;
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private int bufsize = BUFFER_INCREMENT;
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private int end = UNKNOWN;
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private char cached = OUT_OF_BOUNDS;
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// Big enough for a \r\n pair
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// lookBehind[0] = most recent
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// lookBehind[1] = second most recent
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private char[] lookBehind = new char[] { OUT_OF_BOUNDS, OUT_OF_BOUNDS };
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CharIndexedInputStream(InputStream str, int index) {
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if (str instanceof BufferedInputStream) br = (BufferedInputStream) str;
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else br = new BufferedInputStream(str,BUFFER_INCREMENT);
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next();
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if (index > 0) move(index);
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}
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private boolean next() {
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if (end == 1) return false;
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end--; // closer to end
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try {
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if (index != -1) {
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br.reset();
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}
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int i = br.read();
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br.mark(bufsize);
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if (i == -1) {
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end = 1;
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cached = OUT_OF_BOUNDS;
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return false;
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}
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cached = (char) i;
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index = 1;
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} catch (IOException e) {
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e.printStackTrace();
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cached = OUT_OF_BOUNDS;
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return false;
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}
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return true;
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}
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public char charAt(int index) {
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if (index == 0) {
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return cached;
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} else if (index >= end) {
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return OUT_OF_BOUNDS;
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} else if (index == -1) {
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return lookBehind[0];
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} else if (index == -2) {
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return lookBehind[1];
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} else if (index < -2) {
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return OUT_OF_BOUNDS;
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} else if (index >= bufsize) {
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// Allocate more space in the buffer.
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try {
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while (bufsize <= index) bufsize += BUFFER_INCREMENT;
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br.reset();
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br.mark(bufsize);
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br.skip(index-1);
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} catch (IOException e) { }
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} else if (this.index != index) {
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try {
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br.reset();
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br.skip(index-1);
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} catch (IOException e) { }
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}
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char ch = OUT_OF_BOUNDS;
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try {
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int i = br.read();
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this.index = index+1; // this.index is index of next pos relative to charAt(0)
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if (i == -1) {
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// set flag that next should fail next time?
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end = index;
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return ch;
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}
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ch = (char) i;
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} catch (IOException ie) { }
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return ch;
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}
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public boolean move(int index) {
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// move read position [index] clicks from 'charAt(0)'
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boolean retval = true;
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while (retval && (index-- > 0)) retval = next();
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return retval;
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}
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public boolean isValid() {
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return (cached != OUT_OF_BOUNDS);
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}
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}
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