Android Open Source - webview-gm Criterion Matcher

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License

The source code is released under:

Apache License

Java Source Code

/*
 *    Copyright 2012 Werner Bayer//  w  ww  .ja v  a  2 s. c  o m
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package at.pardus.android.webview.gm.util;

/**
 * Class offering static functions to compare a script's exclude/include/match
 * criteria with a URL.
 */
public class CriterionMatcher {

  /**
   * Tests a URL against a criterion (may be a regex or simple glob-type
   * pattern). Case-insensitive.
   * 
   * @param criterion
   *            the pattern to test against
   * @param url
   *            the URL to test
   * @return true if the URL matches the criterion, false else
   * @see <tt><a href="http://wiki.greasespot.net/Include_and_exclude_rules">Rules</a></tt>
   * @see <tt><a href="http://code.google.com/chrome/extensions/match_patterns.html">Match Syntax</a></tt>
   */
  public static boolean test(String criterion, String url) {
    if (criterion.length() == 0) {
      return true;
    }
    criterion = criterion.toLowerCase();
    url = url.toLowerCase();
    if (isRegExp(url)) {
      return url.matches(".*" + convertJsRegExp(criterion) + ".*");
    }
    return testGlob(criterion, url);
  }

  /**
   * Tests a string against a glob-type pattern (supporting only * and the
   * escape character \).
   * 
   * @param pattern
   *            the glob pattern
   * @param str
   *            the string to match against the pattern
   * @return true if the string matches the pattern, false else
   */
  private static boolean testGlob(String pattern, String str) {
    return testGlob(pattern, 0, str, 0);
  }

  /**
   * Recursively tests a string against a glob-type pattern (supporting only *
   * and the escape character \).
   * 
   * @param pattern
   *            the glob pattern
   * @param pInd
   *            the index in the pattern to start testing from
   * @param str
   *            the string to match against the pattern
   * @param sInd
   *            the index in the string to start testing from
   * @return true if the string from the given index to its end matches the
   *         pattern from the given index to its end, false else
   */
  private static boolean testGlob(String pattern, int pInd, String str,
      int sInd) {
    int pLen = pattern.length();
    int sLen = str.length();
    while (true) {
      if (pInd == pLen) {
        return sInd == sLen;
      }
      char pChar = pattern.charAt(pInd);
      if (pChar == '*') {
        pInd++;
        if (pInd >= pLen) {
          return true;
        }
        while (true) {
          if (testGlob(pattern, pInd, str, sInd)) {
            return true;
          }
          if (sInd == sLen) {
            return false;
          }
          sInd++;
        }
      }
      if (sInd == sLen) {
        return false;
      }
      if (pChar == '\\') {
        pInd++;
        if (pInd >= pLen) {
          return false;
        }
        pChar = pattern.charAt(pInd);
      }
      char sChar = str.charAt(sInd);
      if (pChar != sChar) {
        return false;
      }
      pInd++;
      sInd++;
    }
  }

  /**
   * Converts a JS RegExp to a Java string to be used in pattern matching.
   * 
   * @param jsRegExp
   *            the JS RegExp
   * @return the JS regular expression as Java-compatible string
   */
  private static String convertJsRegExp(String jsRegExp) {
    String output = jsRegExp.substring(1, jsRegExp.length() - 1);
    return output;
  }

  /**
   * Tests whether a given string is a JS RegExp.
   * 
   * @param str
   *            the string to test
   * @return true if the string starts with a / and ends with another /
   */
  private static boolean isRegExp(String str) {
    return str.length() >= 2 && str.startsWith("/") && str.endsWith("/");
  }

  /**
   * Private constructor.
   */
  private CriterionMatcher() {

  }

}

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