/*
 * $Id: PatternMatcher.java,v 1.7 2003/11/07 20:16:25 dfs Exp $
 *
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package org.apache.oro.text.regex;


/**
 * The PatternMatcher interface defines the operations a regular
 * expression matcher must implement.  However, the types of the Pattern 
 * implementations recognized by a matcher are not restricted.  Typically
 * PatternMatcher instances will only recognize a specific type of Pattern.
 * For example, the Perl5Matcher only recognizes Perl5Pattern instances.
 * However, none of the PatternMatcher methods are required to throw an
 * exception in case of the use of an invalid pattern.  This is done for
 * efficiency reasons, although usually a CastClassException will be
 * thrown by the Java runtime system if you use the wrong Pattern
 * implementation.  It is the responsibility of the programmer to make
 * sure he uses the correct Pattern instance with a given PatternMatcher
 * instance.  The current version of this package only contains the Perl5
 * suite of pattern matching classes, but future ones for other regular
 * expression grammars may be added and users may also create their own
 * implementations of the provided interfaces. Therefore the programmer
 * should be careful not to mismatch classes.
 *
 * @version @version@
 * @since 1.0
 * @see Pattern
 * @see PatternCompiler
 * @see MatchResult
 */
public interface PatternMatcher {

  /**
   * Determines if a prefix of a string (represented as a char[])
   * matches a given pattern, starting from a given offset into the string.
   * If a prefix of the string matches the pattern, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The char[] to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @param offset The offset at which to start searching for the prefix.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matchesPrefix(char[] input, Pattern pattern, int offset);

  /**
   * Determines if a prefix of a string matches a given pattern.
   * If a prefix of the string matches the pattern, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The String to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matchesPrefix(String input, Pattern pattern);

  /**
   * Determines if a prefix of a string (represented as a char[])
   * matches a given pattern.
   * If a prefix of the string matches the pattern, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The char[] to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matchesPrefix(char[] input, Pattern pattern);

  /**
   * Determines if a prefix of a PatternMatcherInput instance
   * matches a given pattern.  If there is a match, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.  Unlike the
   * {@link #contains(PatternMatcherInput, Pattern)}
   * method, the current offset of the PatternMatcherInput argument
   * is not updated.  You should remember that the region starting
   * from the begin offset of the PatternMatcherInput will be
   * tested for a prefix match.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The PatternMatcherInput to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matchesPrefix(PatternMatcherInput input, Pattern pattern);

  /**
   * Determines if a string exactly matches a given pattern.  If
   * there is an exact match, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * @param input  The String to test for an exact match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matches(String input, Pattern pattern);

  /**
   * Determines if a string (represented as a char[]) exactly matches
   * a given pattern.  If there is an exact match, a MatchResult
   * instance representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * @param input  The char[] to test for a match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matches(char[] input, Pattern pattern);

  /**
   * Determines if the contents of a PatternMatcherInput instance
   * exactly matches a given pattern.  If
   * there is an exact match, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.  Unlike the
   * {@link #contains(PatternMatcherInput, Pattern)}
   * method, the current offset of the PatternMatcherInput argument
   * is not updated.  You should remember that the region between
   * the begin and end offsets of the PatternMatcherInput will be
   * tested for an exact match.
   * <p>
   * @param input  The PatternMatcherInput to test for a match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matches(PatternMatcherInput input, Pattern pattern);

  /**
   * Determines if a string contains a pattern.  If the pattern is
   * matched by some substring of the input, a MatchResult instance
   * representing the <b> first </b> such match is made acessible via 
   * {@link #getMatch()}.  If you want to access
   * subsequent matches you should either use a PatternMatcherInput object
   * or use the offset information in the MatchResult to create a substring
   * representing the remaining input.  Using the MatchResult offset 
   * information is the recommended method of obtaining the parts of the
   * string preceeding the match and following the match.
   * <p>
   * @param input  The String to test for a match.
   * @param pattern  The Pattern to be matched.
   * @return True if the input contains a pattern match, false otherwise.
   */
  public boolean contains(String input, Pattern pattern);

  /**
   * Determines if a string (represented as a char[]) contains a pattern.
   * If the pattern is matched by some substring of the input, a MatchResult
   * instance representing the <b>first</b> such match is made acessible via 
   * {@link #getMatch()}.  If you want to access
   * subsequent matches you should either use a PatternMatcherInput object
   * or use the offset information in the MatchResult to create a substring
   * representing the remaining input.  Using the MatchResult offset 
   * information is the recommended method of obtaining the parts of the
   * string preceeding the match and following the match.
   * <p>
   * @param input  The String to test for a match.
   * @param pattern  The Pattern to be matched.
   * @return True if the input contains a pattern match, false otherwise.
   */
  public boolean contains(char[] input, Pattern pattern);

  /**
   * Determines if the contents of a PatternMatcherInput, starting from the
   * current offset of the input contains a pattern.
   * If a pattern match is found, a MatchResult
   * instance representing the <b>first</b> such match is made acessible via 
   * {@link #getMatch()}.  The current offset of the
   * PatternMatcherInput is set to the offset corresponding to the end
   * of the match, so that a subsequent call to this method will continue
   * searching where the last call left off.  You should remember that the
   * region between the begin and end offsets of the PatternMatcherInput are
   * considered the input to be searched, and that the current offset
   * of the PatternMatcherInput reflects where a search will start from.
   * Matches extending beyond the end offset of the PatternMatcherInput
   * will not be matched.  In other words, a match must occur entirely
   * between the begin and end offsets of the input.  See
   * {@link PatternMatcherInput} for more details.
   * <p>
   * This method is usually used in a loop as follows:
   * <blockquote><pre>
   * PatternMatcher matcher;
   * PatternCompiler compiler;
   * Pattern pattern;
   * PatternMatcherInput input;
   * MatchResult result;
   *
   * compiler = new Perl5Compiler();
   * matcher  = new Perl5Matcher();
   *
   * try {
   *   pattern = compiler.compile(somePatternString);
   * } catch(MalformedPatternException e) {
   *   System.out.println("Bad pattern.");
   *   System.out.println(e.getMessage());
   *   return;
   * }
   *
   * input   = new PatternMatcherInput(someStringInput);
   *
   * while(matcher.contains(input, pattern)) {
   *   result = matcher.getMatch();  
   *   // Perform whatever processing on the result you want.
   * }
   *
   * </pre></blockquote>
   * <p>
   * @param input  The PatternMatcherInput to test for a match.
   * @param pattern  The Pattern to be matched.
   * @return True if the input contains a pattern match, false otherwise.
   */
  public boolean contains(PatternMatcherInput input, Pattern pattern);

  /**
   * Fetches the last match found by a call to a matches() or contains()
   * method.
   * <p>
   * @return A MatchResult instance containing the pattern match found
   *         by the last call to any one of the matches() or contains()
   *         methods.  If no match was found by the last call,
   *         returns null.
   */
  public MatchResult getMatch();
}
