import java.util.regex.Pattern;
 
import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeMatcher;
 
/**
 * Matchers that use regular expressions
 *
 * @author t.wood
 */
public class RegexMatcher
{
   private static abstract class AbstractRegexpMatcher extends TypeSafeMatcher<String>
   {
      protected final String regex;
      protected final Pattern compiledRegex;
 
      private AbstractRegexpMatcher(final String regex)
      {
         this.regex = regex;
         compiledRegex = Pattern.compile(regex);
      }
   }
 
   private static class MatchesRegexpMatcher extends AbstractRegexpMatcher
   {
      private MatchesRegexpMatcher(final String regex)
      {
         super(regex);
      }
 
      @Override
      public boolean matchesSafely(final String item)
      {
         return compiledRegex.matcher(item).matches();
      }
 
      @Override
      public void describeTo(final Description description)
      {
         description.appendText("matches regex ").appendValue(regex);
      }
   }
 
   private static class ContainsMatchRegexpMatcher extends AbstractRegexpMatcher
   {
      private ContainsMatchRegexpMatcher(final String regex)
      {
         super(regex);
      }
 
      @Override
      public boolean matchesSafely(final String item)
      {
         return compiledRegex.matcher(item).find();
      }
 
      @Override
      public void describeTo(final Description description)
      {
         description.appendText("contains match for regex ").appendValue(regex);
      }
   }
 
   /**
    * Match the regexp against the whole input string
    *
    * @param regex the regular expression to match
    *
    * @return a matcher which matches the whole input string
    */
   public static Matcher<String> matches(final String regex)
   {
      return new MatchesRegexpMatcher(regex);
   }
 
   /**
    * Match the regexp against any substring of the input string
    *
    * @param regex the regular expression to match
    *
    * @return a matcher which matches anywhere in the input string
    */
   public static Matcher<String> containsMatch(final String regex)
   {
      return new ContainsMatchRegexpMatcher(regex);
   }
}