Return-Path:
Simple regex pattern matching algorithm. This uses just two wildcards:
*
*
* Escaping these wildcards is not supported .*
matches any sequence of none, one or more characters
* ?
matches any one character
*
Log
implementation.
*/
public Log getLog() {
return log;
}
/**
* Sets the current Log
implementation used by this class.
*/
public void setLog(Log log) {
this.log = log;
}
// --------------------------------------------------------- Public Methods
/**
* Matches using simple regex algorithm.
*
*
* @param basePattern the standard digester path representing the element
* @param regexPattern the regex pattern the path will be tested against
* @return true if the given pattern matches the given path
*/
public boolean match(String basePattern, String regexPattern) {
// check for nulls
if (basePattern == null || regexPattern == null) {
return false;
}
return match(basePattern, regexPattern, 0, 0);
}
// --------------------------------------------------------- Implementations Methods
/**
* Implementation of regex matching algorithm.
* This calls itself recursively.
*/
private boolean match(String basePattern, String regexPattern, int baseAt, int regexAt) {
if (log.isTraceEnabled()) {
log.trace("Base: " + basePattern);
log.trace("Regex: " + regexPattern);
log.trace("Base@" + baseAt);
log.trace("Regex@" + regexAt);
}
// check bounds
if (regexAt >= regexPattern.length()) {
// maybe we've got a match
if (baseAt >= basePattern.length()) {
// ok!
return true;
}
// run out early
return false;
} else {
if (baseAt >= basePattern.length()) {
// run out early
return false;
}
}
// ok both within bounds
char regexCurrent = regexPattern.charAt(regexAt);
switch (regexCurrent) {
case '*':
// this is the tricky case
// check for terminal
if (++regexAt >= regexPattern.length()) {
// this matches anything let - so return true
return true;
}
// go through every subsequent apperance of the next character
// and so if the rest of the regex matches
char nextRegex = regexPattern.charAt(regexAt);
if (log.isTraceEnabled()) {
log.trace("Searching for next '" + nextRegex + "' char");
}
int nextMatch = basePattern.indexOf(nextRegex, baseAt);
while (nextMatch != -1) {
if (log.isTraceEnabled()) {
log.trace("Trying '*' match@" + nextMatch);
}
if (match(basePattern, regexPattern, nextMatch, regexAt)) {
return true;
}
nextMatch = basePattern.indexOf(nextRegex, nextMatch + 1);
}
log.trace("No matches found.");
return false;
case '?':
// this matches anything
return match(basePattern, regexPattern, ++baseAt, ++regexAt);
default:
if (log.isTraceEnabled()) {
log.trace("Camparing " + regexCurrent + " to " + basePattern.charAt(baseAt));
}
if (regexCurrent == basePattern.charAt(baseAt)) {
// still got more to go
return match(basePattern, regexPattern, ++baseAt, ++regexAt);
}
return false;
}
}
}
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