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jlechner |
/* gnu/regexp/REMatchEnumeration.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.Serializable;
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import java.util.Enumeration;
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import java.util.NoSuchElementException;
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/**
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* An REMatchEnumeration enumerates regular expression matches over a
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* given input text. You obtain a reference to an enumeration using
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* the <code>getMatchEnumeration()</code> methods on an instance of
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* RE.
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*
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* <P>
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*
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* REMatchEnumeration does lazy computation; that is, it will not
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* search for a match until it needs to. If you'd rather just get all
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* the matches at once in a big array, use the
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* <code>getAllMatches()</code> methods on RE. However, using an
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* enumeration can help speed performance when the entire text does
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* not need to be searched immediately.
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*
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* <P>
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*
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* The enumerated type is especially useful when searching on a Reader
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* or InputStream, because the InputStream read position cannot be
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* guaranteed after calling <code>getMatch()</code> (see the
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* description of that method for an explanation of why). Enumeration
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* also saves a lot of overhead required when calling
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* <code>getMatch()</code> multiple times.
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*
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* @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
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*/
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public class REMatchEnumeration implements Enumeration, Serializable {
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private static final int YES = 1;
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private static final int MAYBE = 0;
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private static final int NO = -1;
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private int more;
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private REMatch match;
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private RE expr;
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private CharIndexed input;
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private int eflags;
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private int index;
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// Package scope constructor is used by RE.getMatchEnumeration()
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REMatchEnumeration(RE expr, CharIndexed input, int index, int eflags) {
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more = MAYBE;
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this.expr = expr;
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this.input = input;
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this.index = index;
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this.eflags = eflags;
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}
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/** Returns true if there are more matches in the input text. */
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public boolean hasMoreElements() {
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return hasMoreMatches(null);
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}
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/** Returns true if there are more matches in the input text. */
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public boolean hasMoreMatches() {
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return hasMoreMatches(null);
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}
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/** Returns true if there are more matches in the input text.
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* Saves the text leading up to the match (or to the end of the input)
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* in the specified buffer.
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*/
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public boolean hasMoreMatches(StringBuffer buffer) {
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if (more == MAYBE) {
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match = expr.getMatchImpl(input,index,eflags,buffer);
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if (match != null) {
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input.move((match.end[0] > 0) ? match.end[0] : 1);
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index = (match.end[0] > 0) ? match.end[0] + match.offset : index + 1;
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more = YES;
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} else more = NO;
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}
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return (more == YES);
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}
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/** Returns the next match in the input text. */
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public Object nextElement() throws NoSuchElementException {
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return nextMatch();
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}
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/**
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* Returns the next match in the input text. This method is provided
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* for convenience to avoid having to explicitly cast the return value
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* to class REMatch.
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*/
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public REMatch nextMatch() throws NoSuchElementException {
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if (hasMoreElements()) {
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more = (input.isValid()) ? MAYBE : NO;
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return match;
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}
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throw new NoSuchElementException();
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}
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}
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