com.eucalyptus.util.WildcardNameMatcher.java Source code

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Here is the source code for com.eucalyptus.util.WildcardNameMatcher.java

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/*************************************************************************
 * (c) Copyright 2016 Hewlett Packard Enterprise Development Company LP
 *
 * This program 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; version 3 of the License.
 *
 * This program 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 this program.  If not, see http://www.gnu.org/licenses/.
 ************************************************************************/
package com.eucalyptus.util;

import java.util.concurrent.atomic.AtomicReference;
import java.util.regex.Pattern;
import com.google.common.base.CharMatcher;
import com.google.common.base.Splitter;

/**
 *
 */
public class WildcardNameMatcher {

    private static final String PATTERN_DEFAULT = "(?!x)x"; // x but not x, will not match anything
    private static final Pattern PATTERN_DEFAULT_COMPILED = Pattern.compile(PATTERN_DEFAULT);

    private AtomicReference<Pair<String, Pattern>> patternPairRef = new AtomicReference<>(
            Pair.pair("", PATTERN_DEFAULT_COMPILED));

    public boolean matches(final String patternList, final CharSequence value) {
        final Pattern pattern = getPattern(patternList);
        return pattern.matcher(value).matches();
    }

    private Pattern getPattern(final String patternList) {
        final Pair<String, Pattern> patternPair = patternPairRef.get();
        if (patternPair == null || !patternPair.getLeft().equals(patternList)) {
            final Pattern pattern = buildPattern(patternList);
            patternPairRef.compareAndSet(patternPair, Pair.pair(patternList, pattern));
            return pattern;
        } else {
            return patternPair.getRight();
        }
    }

    private Pattern buildPattern(final String patternList) {
        if (!patternList.trim().isEmpty()) {
            final Splitter splitter = Splitter.on(CharMatcher.WHITESPACE.or(CharMatcher.anyOf(",;|"))).trimResults()
                    .omitEmptyStrings();
            final StringBuilder builder = new StringBuilder();
            builder.append("(");
            for (final String nameWithWildcards : splitter.split(patternList)) {
                builder.append(toPattern(nameWithWildcards));
                builder.append('|');
            }
            builder.append(PATTERN_DEFAULT);
            builder.append(")");
            return Pattern.compile(builder.toString());

        }
        return PATTERN_DEFAULT_COMPILED;
    }

    private static String toPattern(final String nameWithWildcards) {
        if (!nameWithWildcards.matches("[\\w*.-]+")) {
            return PATTERN_DEFAULT;
        }
        return nameWithWildcards.replace(".", "\\.").replace("*", ".*");
    }

}