001    /*
002     * SonarQube, open source software quality management tool.
003     * Copyright (C) 2008-2013 SonarSource
004     * mailto:contact AT sonarsource DOT com
005     *
006     * SonarQube is free software; you can redistribute it and/or
007     * modify it under the terms of the GNU Lesser General Public
008     * License as published by the Free Software Foundation; either
009     * version 3 of the License, or (at your option) any later version.
010     *
011     * SonarQube is distributed in the hope that it will be useful,
012     * but WITHOUT ANY WARRANTY; without even the implied warranty of
013     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014     * Lesser General Public License for more details.
015     *
016     * You should have received a copy of the GNU Lesser General Public License
017     * along with this program; if not, write to the Free Software Foundation,
018     * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
019     */
020    package org.sonar.channel;
021    
022    import java.util.regex.Matcher;
023    import java.util.regex.Pattern;
024    
025    /**
026     * The RegexChannel can be used to be called each time the next characters in the character stream match a regular expression
027     */
028    public abstract class RegexChannel<O> extends Channel<O> {
029    
030      private final StringBuilder tmpBuilder = new StringBuilder();
031      private final Matcher matcher;
032    
033      /**
034       * Create a RegexChannel object with the required regular expression
035       *
036       * @param regex
037       *          regular expression to be used to try matching the next characters in the stream
038       */
039      public RegexChannel(String regex) {
040        matcher = Pattern.compile(regex).matcher("");
041      }
042    
043      @Override
044      public final boolean consume(CodeReader code, O output) {
045        if (code.popTo(matcher, tmpBuilder) > 0) {
046          consume(tmpBuilder, output);
047          tmpBuilder.delete(0, tmpBuilder.length());
048          return true;
049        }
050        return false;
051      }
052    
053      /**
054       * The consume method is called each time the regular expression used to create the RegexChannel object matches the next characters in the
055       * character streams.
056       *
057       * @param token
058       *          the token consumed in the character stream and matching the regular expression
059       * @param the
060       *          OUPUT object which can be optionally fed
061       */
062      protected abstract void consume(CharSequence token, O output);
063    
064    }