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/*
* This file is part of *** M y C o R e ***
* See http://www.mycore.de/ for details.
*
* MyCoRe is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* MyCoRe 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with MyCoRe. If not, see .
*/
package org.mycore.common.function;
import java.nio.file.FileSystem;
import java.util.regex.PatternSyntaxException;
import org.mycore.datamodel.niofs.MCRAbstractFileSystem;
/**
* @author Thomas Scheffler (yagee)
*
*/
public class MCRFunctions {
private static char END_OF_PATTERN = 0;
private static final String GLOB_RESERVED_CHARS = "?*\\{[";
private static final String REGEX_RESERVED_CHARS = "^$.{()+*[]|";
/**
* converts a Glob pattern into a regex pattern.
* @param globPattern a pattern like "/foo/*{@literal}/bar/*.txt"
* @return
* @see FileSystem#getPathMatcher(String) "glob" style
*/
public static String convertGlobToRegex(final String globPattern) {
boolean isInGroup = false;
final StringBuilder regex = new StringBuilder("^");
int nextPos = 0;
while (nextPos < globPattern.length()) {
final char c = globPattern.charAt(nextPos++);
switch (c) {
//Character handling
case '\\':
nextPos = escapeCharacter(regex, globPattern, nextPos);
break;
case '[':
nextPos = addCharacterClass(regex, globPattern, nextPos);
break;
case '*':
nextPos = handleWildcard(regex, globPattern, nextPos);
break;
case '?':
regex.append("[^/]");
break;
//Group handling
case '{':
isInGroup = startGroup(regex, globPattern, nextPos, isInGroup);
break;
case '}':
isInGroup = endGroup(regex, isInGroup);
break;
case ',':
if (isInGroup) {
regex.append(")|(?:");//separate values
} else {
regex.append(',');
}
break;
default:
if (isRegexReserved(c)) {
regex.append('\\');
}
regex.append(c);
}
}
if (isInGroup) {
throw new PatternSyntaxException("Missing '}'.", globPattern, nextPos - 1);
}
return regex.append('$').toString();
}
private static int addCharacterClass(final StringBuilder regex, final String globPattern, int nextPos) {
regex.append("[[^/]&&[");
if (nextCharAt(globPattern, nextPos) == '^') {
// escape the regex negation char if it appears
regex.append("\\^");
nextPos++;
} else {
// negation
if (nextCharAt(globPattern, nextPos) == '!') {
regex.append('^');
nextPos++;
}
// hyphen allowed at start
if (nextCharAt(globPattern, nextPos) == '-') {
regex.append('-');
nextPos++;
}
}
boolean inRange = false;
char rangeStartChar = 0;
char curChar = '[';
while (nextPos < globPattern.length()) {
curChar = globPattern.charAt(nextPos++);
if (curChar == ']') {
break;
}
if (curChar == MCRAbstractFileSystem.SEPARATOR) {
throw new PatternSyntaxException("Chracter classes cannot cross directory boundaries.", globPattern,
nextPos - 1);
}
if (curChar == '\\' || curChar == '[' || curChar == '&' && nextCharAt(globPattern, nextPos) == '&') {
// escape '\', '[' or "&&"
regex.append('\\');
}
regex.append(curChar);
if (curChar == '-') {
if (!inRange) {
throw new PatternSyntaxException("Invalid range.", globPattern, nextPos - 1);
}
curChar = nextCharAt(globPattern, nextPos++);
if (curChar == END_OF_PATTERN || curChar == ']') {
break;
}
if (curChar < rangeStartChar) {
throw new PatternSyntaxException("Invalid range.", globPattern, nextPos - 3);
}
regex.append(curChar);
inRange = false;
} else {
inRange = true;
rangeStartChar = curChar;
}
}
if (curChar != ']') {
throw new PatternSyntaxException("Missing ']'.", globPattern, nextPos - 1);
}
regex.append("]]");
return nextPos;
}
private static boolean endGroup(final StringBuilder regex, boolean isInGroup) {
if (isInGroup) {
isInGroup = false;
regex.append("))");
} else {
regex.append('}');
}
return isInGroup;
}
private static int escapeCharacter(final StringBuilder regex, final String globPattern, int nextPos) {
if (nextPos == globPattern.length()) {
throw new PatternSyntaxException("No character left to escape.", globPattern, nextPos - 1);
}
final char next = globPattern.charAt(nextPos++);
if (isGlobReserved(next) || isRegexReserved(next)) {
regex.append('\\');
}
regex.append(next);
return nextPos;
}
private static int handleWildcard(final StringBuilder regex, final String globPattern, int nextPos) {
if (nextCharAt(globPattern, nextPos) == '*') {
//The ** characters matches zero or more characters crossing directory boundaries.
regex.append(".*");
nextPos++;
} else {
//The * character matches zero or more characters of a name component without crossing directory boundaries
regex.append("[^/]*");
}
return nextPos;
}
private static boolean isGlobReserved(final char c) {
return GLOB_RESERVED_CHARS.indexOf(c) != -1;
}
private static boolean isRegexReserved(final char c) {
return REGEX_RESERVED_CHARS.indexOf(c) != -1;
}
private static char nextCharAt(final String glob, final int i) {
if (i < glob.length()) {
return glob.charAt(i);
}
return END_OF_PATTERN;
}
private static boolean startGroup(final StringBuilder regex, final String globPattern, final int nextPos,
final boolean isInGroup) {
if (isInGroup) {
throw new PatternSyntaxException("Nested groups are not supported.", globPattern, nextPos - 1);
}
regex.append("(?:(?:");
return true;
}
}
