001 /* 002 * Sonar, open source software quality management tool. 003 * Copyright (C) 2008-2011 SonarSource 004 * mailto:contact AT sonarsource DOT com 005 * 006 * Sonar 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 * Sonar 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 017 * License along with Sonar; if not, write to the Free Software 018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02 019 */ 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<OUTPUT> extends Channel<OUTPUT> { 029 030 private final StringBuilder tmpBuilder = new StringBuilder(); 031 private final Matcher matcher; 032 private final String regex; 033 034 /** 035 * Create a RegexChannel object with the required regular expression 036 * 037 * @param regex 038 * regular expression to be used to try matching the next characters in the stream 039 */ 040 public RegexChannel(String regex) { 041 matcher = Pattern.compile(regex).matcher(""); 042 this.regex = regex; 043 } 044 045 @Override 046 public final boolean consume(CodeReader code, OUTPUT output) { 047 try { 048 if (code.popTo(matcher, tmpBuilder) > 0) { 049 consume(tmpBuilder, output); 050 tmpBuilder.delete(0, tmpBuilder.length()); 051 return true; 052 } 053 return false; 054 } catch (StackOverflowError e) { 055 throw new IllegalArgumentException( 056 "The regular expression " 057 + regex 058 + " has led to a stack overflow error. " 059 + "This error is certainly due to an inefficient use of alternations. See http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5050507", 060 e); 061 } 062 } 063 064 /** 065 * The consume method is called each time the regular expression used to create the RegexChannel object matches the next characters in the 066 * character streams. 067 * 068 * @param token 069 * the token consumed in the character stream and matching the regular expression 070 * @param the 071 * OUPUT object which can be optionally fed 072 */ 073 protected abstract void consume(CharSequence token, OUTPUT output); 074 }