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/jEdit/tags/jedit-4-1-pre5/gnu/regexp/REMatch.java

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Java | 244 lines | 106 code | 22 blank | 116 comment | 24 complexity | 07b75eafad84484fdb56938d9964f477 MD5 | raw file
  1/*
  2 *  gnu/regexp/REMatch.java
  3 *  Copyright (C) 1998-2001 Wes Biggs
  4 *
  5 *  This library is free software; you can redistribute it and/or modify
  6 *  it under the terms of the GNU Lesser General Public License as published
  7 *  by the Free Software Foundation; either version 2.1 of the License, or
  8 *  (at your option) any later version.
  9 *
 10 *  This library is distributed in the hope that it will be useful,
 11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13 *  GNU Lesser General Public License for more details.
 14 *
 15 *  You should have received a copy of the GNU Lesser General Public License
 16 *  along with this program; if not, write to the Free Software
 17 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 18 */
 19
 20package gnu.regexp;
 21import java.io.Serializable;
 22
 23/**
 24 * An instance of this class represents a match
 25 * completed by a gnu.regexp matching function. It can be used
 26 * to obtain relevant information about the location of a match
 27 * or submatch.
 28 *
 29 * @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
 30 */
 31public final class REMatch implements Serializable, Cloneable {
 32    private String matchedText;
 33
 34    // These variables are package scope for fast access within the engine
 35    int eflags; // execution flags this match was made using
 36
 37    // Offset in source text where match was tried.  This is zero-based;
 38    // the actual position in the source text is given by (offset + anchor).
 39    int offset;
 40
 41    // Anchor position refers to the index into the source input
 42    // at which the matching operation began.
 43    // This is also useful for the ANCHORINDEX option.
 44    int anchor;
 45
 46    // Package scope; used by RE.
 47    int index; // used while matching to mark current match position in input
 48    int[] start; // start positions (relative to offset) for each (sub)exp.
 49    int[] end;   // end positions for the same
 50    REMatch next; // other possibility (to avoid having to use arrays)
 51
 52    public Object clone() {
 53	try {
 54	    REMatch copy = (REMatch) super.clone();
 55	    copy.next = null;
 56
 57	    copy.start = (int[]) start.clone();
 58	    copy.end = (int[]) end.clone();
 59
 60	    return copy;
 61	} catch (CloneNotSupportedException e) {
 62	    throw new Error(); // doesn't happen
 63	}
 64    }
 65
 66    void assignFrom(REMatch other) {
 67	start = other.start;
 68	end = other.end;
 69	index = other.index;
 70	// need to deep clone?
 71	next = other.next;
 72    }
 73
 74    REMatch(int subs, int anchor, int eflags) {
 75	start = new int[subs+1];
 76	end = new int[subs+1];
 77	this.anchor = anchor;
 78	this.eflags = eflags;
 79	clear(anchor);
 80    }
 81
 82    void finish(CharIndexed text) {
 83	start[0] = 0;
 84	StringBuffer sb = new StringBuffer();
 85	int i;
 86	for (i = 0; i < end[0]; i++)
 87	    sb.append(text.charAt(i));
 88	matchedText = sb.toString();
 89	for (i = 0; i < start.length; i++) {
 90	    // If any subexpressions didn't terminate, they don't count
 91	    // TODO check if this code ever gets hit
 92	    if ((start[i] == -1) ^ (end[i] == -1)) {
 93		start[i] = -1;
 94		end[i] = -1;
 95	    }
 96	}
 97	next = null; // cut off alternates
 98    }
 99    
100    /** Clears the current match and moves the offset to the new index. */
101    void clear(int index) {
102	offset = index;
103	this.index = 0;
104	for (int i = 0; i < start.length; i++) {
105	    start[i] = end[i] = -1;
106	}
107	next = null; // cut off alternates
108    }
109    
110    /**
111     * Returns the string matching the pattern.  This makes it convenient
112     * to write code like the following:
113     * <P>
114     * <code> 
115     * REMatch myMatch = myExpression.getMatch(myString);<br>
116     * if (myMatch != null) System.out.println("Regexp found: "+myMatch);
117     * </code>
118     */
119    public String toString() {
120	return matchedText;
121    }
122    
123    /**
124     * Returns the index within the input text where the match in its entirety
125     * began.
126     */
127    public int getStartIndex() {
128	return offset + start[0];
129    }
130    
131    /**
132     * Returns the index within the input string where the match in
133     * its entirety ends.  The return value is the next position after
134     * the end of the string; therefore, a match created by the
135     * following call:
136     *
137     * <P>
138     * <code>REMatch myMatch = myExpression.getMatch(myString);</code>
139     * <P>
140     * can be viewed (given that myMatch is not null) by creating
141     * <P>
142     * <code>String theMatch = myString.substring(myMatch.getStartIndex(),
143     * myMatch.getEndIndex());</code>
144     * <P>
145     * But you can save yourself that work, since the <code>toString()</code>
146     * method (above) does exactly that for you.  
147     */
148    public int getEndIndex() {
149	return offset + end[0];
150    }
151  
152    /**
153     * Returns the string matching the given subexpression.  The subexpressions
154     * are indexed starting with one, not zero.  That is, the subexpression
155     * identified by the first set of parentheses in a regular expression
156     * could be retrieved from an REMatch by calling match.toString(1).
157     *
158     * @param sub Index of the subexpression.
159     */
160    public String toString(int sub) {
161	if ((sub >= start.length) || (start[sub] == -1)) return "";
162	return (matchedText.substring(start[sub],end[sub]));
163    }
164    
165    /** 
166     * Returns the index within the input string used to generate this match
167     * where subexpression number <i>sub</i> begins, or <code>-1</code> if
168     * the subexpression does not exist.  The initial position is zero.
169     *
170     * @param sub Subexpression index
171     * @deprecated Use getStartIndex(int) instead.
172     */
173    public int getSubStartIndex(int sub) {
174	if (sub >= start.length) return -1;
175	int x = start[sub];
176	return (x == -1) ? x : offset + x;
177    }
178    
179    /** 
180     * Returns the index within the input string used to generate this match
181     * where subexpression number <i>sub</i> begins, or <code>-1</code> if
182     * the subexpression does not exist.  The initial position is zero.
183     *
184     * @param sub Subexpression index
185     * @since gnu.regexp 1.1.0
186     */
187    public int getStartIndex(int sub) {
188	if (sub >= start.length) return -1;
189	int x = start[sub];
190	return (x == -1) ? x : offset + x;
191    }
192  
193    /** 
194     * Returns the index within the input string used to generate this match
195     * where subexpression number <i>sub</i> ends, or <code>-1</code> if
196     * the subexpression does not exist.  The initial position is zero.
197     *
198     * @param sub Subexpression index
199     * @deprecated Use getEndIndex(int) instead
200     */
201    public int getSubEndIndex(int sub) {
202	if (sub >= start.length) return -1;
203	int x = end[sub];
204	return (x == -1) ? x : offset + x;
205    }
206    
207    /** 
208     * Returns the index within the input string used to generate this match
209     * where subexpression number <i>sub</i> ends, or <code>-1</code> if
210     * the subexpression does not exist.  The initial position is zero.
211     *
212     * @param sub Subexpression index
213     */
214    public int getEndIndex(int sub) {
215	if (sub >= start.length) return -1;
216	int x = end[sub];
217	return (x == -1) ? x : offset + x;
218    }
219    
220    /**
221     * Substitute the results of this match to create a new string.
222     * This is patterned after PERL, so the tokens to watch out for are
223     * <code>$0</code> through <code>$9</code>.  <code>$0</code> matches
224     * the full substring matched; <code>$<i>n</i></code> matches
225     * subexpression number <i>n</i>.
226     *
227     * @param input A string consisting of literals and <code>$<i>n</i></code> tokens.
228     */
229    public String substituteInto(String input) {
230	// a la Perl, $0 is whole thing, $1 - $9 are subexpressions
231	StringBuffer output = new StringBuffer();
232	int pos;
233	for (pos = 0; pos < input.length()-1; pos++) {
234	    if ((input.charAt(pos) == '$') && (Character.isDigit(input.charAt(pos+1)))) {
235		int val = Character.digit(input.charAt(++pos),10);
236		if (val < start.length) {
237		    output.append(toString(val));
238		} 
239	    } else output.append(input.charAt(pos));
240	}
241	if (pos < input.length()) output.append(input.charAt(pos));
242	return output.toString();
243    }
244}