/*
* gnu/regexp/REMatchEnumeration.java
* Copyright (C) 1998 Wes Biggs
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This library 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 Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
package gnu.regexp;
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* An REMatchEnumeration enumerates regular expression matches over a given
* input text. You obtain a reference to an enumeration using the
* <code>getMatchEnumeration()</code> methods on an instance of RE.
* <P>
* REMatchEnumeration does lazy computation; that is, it will not search for
* a match until it needs to. If you'd rather just get all the matches at
* once in a big array, use the <code>getAllMatches()</code> methods on RE.
* However, using an enumeration can help speed performance when the entire
* text does not need to be searched immediately.
* <P>
* The enumerated type is especially useful when searching on an InputStream,
* because the InputStream read position cannot be guaranteed after calling
* <code>getMatch()</code> (see the description of that method for an
* explanation of why). Enumeration also saves a lot of overhead required
* when calling <code>getMatch()</code> multiple times.
*
* @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
*/
public class REMatchEnumeration implements Enumeration {
private static final int YES = 1;
private static final int MAYBE = 0;
private static final int NO = -1;
private int m_more;
private REMatch m_match;
private RE m_expr;
private CharIndexed m_input;
private int m_index;
private int m_eflags;
private StringBuffer m_buffer;
// Package scope constructor is used by RE.getMatchEnumeration()
REMatchEnumeration(RE expr, CharIndexed input, int index, int eflags) {
m_more = MAYBE;
m_expr = expr;
m_input = input;
m_index = index;
m_eflags = eflags;
}
/** Returns true if there are more matches in the input text. */
public boolean hasMoreElements() {
return hasMoreMatches(null);
}
/** Returns true if there are more matches in the input text. */
public boolean hasMoreMatches() {
return hasMoreMatches(null);
}
/** Returns true if there are more matches in the input text.
* Saves the text leading up to the match (or to the end of the input)
* in the specified buffer.
*/
public boolean hasMoreMatches(StringBuffer f_buffer) {
if (m_more == MAYBE) {
m_match = m_expr.getMatchImpl(m_input,m_index,m_eflags,f_buffer);
if (m_match != null) {
m_index = m_match.getEndIndex();
m_input.move((m_match.end[0] > 0) ? m_match.end[0] : 1);
m_more = YES;
} else m_more = NO;
}
return (m_more == YES);
}
/** Returns the next match in the input text. */
public Object nextElement() throws NoSuchElementException {
return nextMatch();
}
/**
* Returns the next match in the input text. This method is provided
* for convenience to avoid having to explicitly cast the return value
* to class REMatch.
*/
public REMatch nextMatch() throws NoSuchElementException {
if (hasMoreElements()) {
m_more = MAYBE;
return m_match;
}
throw new NoSuchElementException();
}
}