package com.atlassian.gzipfilter.selector;
   
   import org.apache.commons.lang.StringUtils;
   
   import java.util.Collections;
   import java.util.HashMap;
   import java.util.Map;
   import java.util.regex.Pattern;
   
  /**
   * This class may be called by multiple threads - it is internally synchronised.
   */
  public class PatternMatcher
  {
      // Although synchronisation here may be a point of contention,
      // when running with 20 threads, uncached gives a performance time of
      // 27 seconds.  Cached gives 13 seconds.
      // The performance test can be found in TestPatternMatcher
      private final Map patternCache = Collections.synchronizedMap(new HashMap());
  
      /**
       * @param contentType     The content type to match
       * @param mimeTypesToGzip A comma separated list of regular expressions to match against
       * @return True if the content type matches a least one of the regular expressions
       */
      public boolean matches(String contentType, String mimeTypesToGzip)
      {
          final String[] mimeTypes = StringUtils.split(mimeTypesToGzip,",");
          for (int i = 0; i < mimeTypes.length; i++)
          {
              String mimeType = mimeTypes[i].trim();
              Pattern p = (Pattern) patternCache.get(mimeType);
              if (p == null)
              {
                  p = Pattern.compile(mimeType);
                  patternCache.put(mimeType, p);
              }
  
              if (p.matcher(contentType).matches())
              {
                  return true;
              }
          }
          return false;
      }
  
  }