org.apache.cocoon.util.WildcardMatcherHelper Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cocoon.util;
import org.apache.regexp.RE;
import org.apache.regexp.RECompiler;
import org.apache.regexp.REProgram;
import java.util.HashMap;
import java.util.Map;
/**
* This class is an utility class that perform wildcard-patterns matching and isolation.
*
* @version $Id: WildcardMatcherHelper.java 587751 2007-10-24 02:41:36Z vgritsenko $
*/
public class WildcardMatcherHelper {
//~ Static fields/initializers -----------------------------------------------------------------
/** Default path separator: "/" */
public static final char ESC = '\\';
/** Default path separator: "/" */
public static final char PATHSEP = '/';
/** Default path separator: "/" */
public static final char STAR = '*';
//~ Methods ------------------------------------------------------------------------------------
/**
* Match a pattern agains a string and isolates wildcard replacement into a Map.
*
* Here is how the matching algorithm works:
*
*
* -
* The '*' character, meaning that zero or more characters (excluding the path separator '/')
* are to be matched.
*
* -
* The '**' sequence, meaning that zero or more characters (including the path separator '/')
* are to be matched.
*
* -
* The '\*' sequence is honored as a litteral '*' character, not a wildcard
*
*
*
* When more than two '*' characters, not separated by another character, are found their value is
* considered as '**' and immediate succeeding '*' are skipped.
*
* The '**' wildcard is greedy and thus the following sample matches as {"foo/bar","baz","bug"}:
*
* - pattern
* - STAR,STAR,PATHSEP,STAR,PATHSEP,STAR,STAR (why can't I express it litterally?)
*
- string
* - foo/bar/baz/bug
*
* The first '**' in the pattern will suck up as much as possible without making the match fail.
*
* @param pat The pattern string.
* @param str The string to math agains the pattern
*
* @return a Map containing the representation of the extracted pattern. The extracted patterns are
* keys in the Map from left to right beginning with "1" for te left most, "2" for the next,
* a.s.o. The key "0" is the string itself. If the return value is null, string does not match to the
* pattern .
*/
public static Map match(final String pat,
final String str) {
Matcher matcher;
synchronized (cache) {
matcher = (Matcher) cache.get(pat);
if ( matcher == null ) {
matcher = new Matcher(pat);
cache.put(pat, matcher);
}
}
String[] list = matcher.getMatches(str);
if ( list == null )
return null;
int n = list.length;
Map map = new HashMap(n * 2 + 1);
for ( int i = 0; i < n; i++ ) {
map.put(String.valueOf(i), list[i]);
}
return map;
}
/** Cache for compiled pattern matchers */
private static final Map cache = new HashMap();
//~ Inner Classes ------------------------------------------------------------------------------
/**
* The private matcher class
*/
private static class Matcher {
/** Regexp to split constant parts from front and back leaving wildcards in the middle. */
private static final REProgram splitter;
static {
final String fixedRE = "([^*\\\\]*)";
final String wcardRE = "(.*[*\\\\])";
final String splitRE = "^" + fixedRE + wcardRE + fixedRE + "$";
splitter = new RECompiler().compile(splitRE);
}
/** Wildcard types to short-cut simple '*' and "**' matches. */
private static final int WC_CONST = 0;
private static final int WC_STAR = 1;
private static final int WC_STARSTAR = 2;
private static final int WC_REGEXP = 3;
//~ Instance fields ------------------------------------------------------------------------
// All fields declared final to emphasize requirement to be thread-safe.
/** Fixed text at start of pattern. */
private final String prefix;
/** Fixed text at end of pattern. */
private final String suffix;
/** Length of prefix and suffix. */
private final int fixlen;
/** Wildcard type of pattern. */
private final int wctype;
/** Compiled regexp equivalent to wildcard pattern between prefix and suffix. */
private final REProgram regexp;
//~ Constructors ---------------------------------------------------------------------------
/**
* Creates a new Matcher object.
*
* @param pat The pattern
* @param str The string
*/
Matcher(final String pat) {
RE re = new RE(splitter);
if ( re.match(pat) ) {
// Split pattern into (foo/)(*)(/bar).
prefix = re.getParen(1);
String wildcard = re.getParen(2);
String tail = re.getParen(3);
// If wildcard ends with \ then add the first char of postfix to wildcard.
if ( tail.length() != 0 && wildcard.charAt(wildcard.length() - 1) == ESC ) {
wildcard = wildcard + tail.substring(0, 1);
suffix = tail.substring(1);
}
else {
suffix = tail;
}
// Use short-cuts for single * or ** wildcards
if ( wildcard.equals("*") ) {
wctype = WC_STAR;
regexp = null;
}
else if ( wildcard.equals("**") ) {
wctype = WC_STARSTAR;
regexp = null;
}
else {
wctype = WC_REGEXP;
regexp = compileRegexp(wildcard);
}
}
else {
// Pattern is a constant without '*' or '\'.
prefix = pat;
suffix = "";
wctype = WC_CONST;
regexp = null;
}
fixlen = prefix.length() + suffix.length();
}
//~ Methods --------------------------------------------------------------------------------
/**
* Match string against pattern.
*
* @param str The string
* @return list of wildcard matches, null if match failed
*/
String[] getMatches(final String str) {
// Protect against 'foo' matching 'foo*foo'.
if ( str.length() < fixlen )
return null;
if ( !str.startsWith(prefix) )
return null;
if ( !str.endsWith(suffix) )
return null;
String infix = str.substring(prefix.length(), str.length() - suffix.length());
if ( wctype == WC_REGEXP ) {
RE re = new RE(regexp);
if ( !re.match(infix) )
return null;
int n = re.getParenCount();
String[] list = new String[n];
list[0] = str;
for ( int i = 1; i < n; i++ )
list[i] = re.getParen(i);
return list;
}
if ( wctype == WC_CONST ) {
if ( infix.length() != 0 )
return null;
return new String[] {
str
};
}
if ( wctype == WC_STAR ) {
if ( infix.indexOf(PATHSEP) != -1 )
return null;
}
return new String[] {
str, infix
};
}
}
/**
* Compile wildcard pattern into regexp pattern.
*
* @param pat The wildcard pattern
* @return compiled regexp program.
*/
private static REProgram compileRegexp(String pat) {
StringBuffer repat = new StringBuffer(pat.length() * 6);
repat.append('^');
// Add an extra character to allow unchecked wcpat[i+1] accesses.
// Unterminated ESC sequences are silently handled as '\\'.
char[] wcpat = (pat + ESC).toCharArray();
for ( int i = 0, n = pat.length(); i < n; i++ ) {
char ch = wcpat[i];
if ( ch == STAR ) {
if ( wcpat[i + 1] != STAR ) {
repat.append("([^/]*)");
continue;
}
// Handle two and more '*' as single '**'.
while ( wcpat[i + 1] == STAR )
i++;
repat.append("(.*)");
continue;
}
// Match ESC+ESC and ESC+STAR as literal ESC and STAR which needs to be escaped
// in regexp. Match ESC+other as two characters ESC+other where other may also
// need to be escaped in regexp.
if ( ch == ESC ) {
ch = wcpat[++i];
if ( ch != ESC && ch != STAR )
repat.append("\\\\");
}
if ( ch >= 'a' && ch <= 'z' || ch >= 'A' && ch <= 'Z' || ch >= '0' && ch <= '9'
|| ch == '/' ) {
repat.append(ch);
continue;
}
repat.append('\\');
repat.append(ch);
}
repat.append('$');
return new RECompiler().compile(repat.toString());
}
}