matchactionprocessor.java

jakarta-oro-2.0.8 正则表达式 引擎 源代码

/*
 * $Id: MatchActionProcessor.java,v 1.10 2003/11/07 20:16:24 dfs Exp $
 *
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package org.apache.oro.text;
 
import java.io.*;
import java.util.*;

import org.apache.oro.text.regex.*;

/**
 * The MatchActionProcessor class provides AWK-like line by line filtering
 * of a text stream, pattern action pair association, and field splitting
 * based on a registered separator.  However, the class can be used with
 * any compatible PatternMatcher/PatternCompiler implementations and
 * need not use the AWK matching classes in org.apache.oro.text.awk.  In fact,
 * the default matcher and compiler used by the class are Perl5Matcher and
 * Perl5Compiler from org.apache.oro.text.regex.
 * <p>
 * To completely understand how to use MatchActionProcessor, you should first
 * look at {@link MatchAction} and {@link MatchActionInfo}.
 * A MatchActionProcessor is first initialized with
 * the desired PatternCompiler and PatternMatcher instances to use to compile
 * patterns and perform matches.  Then, optionally, a field separator may
 * be registered with {@link #setFieldSeparator setFieldSeparator()}
 * Finally, as many pattern action pairs as desired are registerd with
 * {@link #addAction addAction()} before processing the input
 * with {@link #processMatches processMatches()}.  Pattern action
 * pairs are processed in the order they were registered.
 * <p>
 * The look of added actions can closely mirror that of AWK when anonymous
 * classes are used.  Here's an example of how you might use
 * MatchActionProcessor to extract only the second column of a semicolon
 * delimited file:
 * <p>
 * <pre>
 * import java.io.*;
 *
 * import org.apache.oro.text.*;
 * import org.apache.oro.text.regex.*;
 *
 * public final class semicolon {
 *
 *  public static final void main(String[] args) {
 *    MatchActionProcessor processor = new MatchActionProcessor();
 *
 *    try {
 *      processor.setFieldSeparator(";");
 *      // Using a null pattern means to perform the action for every line.
 *      processor.addAction(null, new MatchAction() {
 *        public void processMatch(MatchActionInfo info) {
 *	    // We assume the second column exists
 *          info.output.println(info.fields.elementAt(1));
 *        }
 *     });
 *   } catch(MalformedPatternException e) {
 *     e.printStackTrace();
 *     System.exit(1);
 *   }
 *
 *   try {
 *      processor.processMatches(System.in, System.out);
 *   } catch(IOException e) {
 *     e.printStackTrace();
 *     System.exit(1);
 *   }
 *  }
 *}
 * </pre>
 * You can redirect the following sample input to stdin to test the code:
 * <pre>
 * 1;Trenton;New Jersey
 * 2;Annapolis;Maryland
 * 3;Austin;Texas
 * 4;Richmond;Virginia
 * 5;Harrisburg;Pennsylvania
 * 6;Honolulu;Hawaii
 * 7;Santa Fe;New Mexico
 * </pre>
 *
 * @version @version@
 * @since 1.0
 * @see MatchAction
 * @see MatchActionInfo
 */
public final class MatchActionProcessor {
  private Pattern __fieldSeparator = null;
  private PatternCompiler __compiler;
  private PatternMatcher  __matcher;
  // If a pattern is null, it means to do it for every line.
  private Vector __patterns   = new Vector();
  private Vector __actions    = new Vector();

  private MatchAction __defaultAction = new DefaultMatchAction();

  /**
   * Creates a new MatchActionProcessor instance initialized with the specified
   * pattern compiler and matcher.  The field separator is set to null by
   * default, which means that matched lines will not be split into separate
   * fields unless the field separator is set with
   * {@link #setFieldSeparator setFieldSeparator()}.
   * <p>
   * @param compiler  The PatternCompiler to use to compile registered
   *                  patterns.
   * @param matcher   The PatternMatcher to use when searching for matches.
   */
  public MatchActionProcessor(PatternCompiler compiler, PatternMatcher matcher)
  {
    __compiler = compiler;
    __matcher  = matcher;
  }

  /**
   * Default constructor for MatchActionProcessor.  Same as calling
   * <blockquote><code>
   * MatchActionProcessor(new Perl5Compiler(), new Perl5Matcher());
   * </code></blockquote>
   */
  public MatchActionProcessor() {
    this(new Perl5Compiler(), new Perl5Matcher());
  }


  /**
   * Registers a pattern action pair, providing options to be used to
   * compile the pattern.  If a pattern is null, the action
   * is performed for every line of input.
   * <p>
   * @param pattern  The pattern to bind to an action.
   * @param options  The compilation options to use for the pattern.
   * @param action   The action to associate with the pattern.
   * @exception MalformedPatternException If the pattern cannot be compiled.
   */
  public void addAction(String pattern, int options, MatchAction action)
       throws MalformedPatternException
  {
    if(pattern != null)
      __patterns.addElement(__compiler.compile(pattern, options));
    else
      __patterns.addElement(null);
    __actions.addElement(action);
  }

  /**
   * Binds a patten to the default action, providing options to be
   * used to compile the pattern.  The default action is to simply print
   * the matched line to the output.  If a pattern is null, the action
   * is performed for every line of input.
   * <p>
   * @param pattern  The pattern to bind to an action.
   * @param options  The compilation options to use for the pattern.
   * @exception MalformedPatternException If the pattern cannot be compiled.
   */
  public void addAction(String pattern, int options)
       throws MalformedPatternException
  {
    addAction(pattern, options, __defaultAction);
  }

  /**
   * Binds a patten to the default action.  The default action is to simply
   * print the matched line to the output.  If a pattern is null, the action