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petitparser/lib/src/debug/progress.dart

-part of debug;
-
-/**
- * Returns a transformed [parser] that when being used to read input
- * visually prints its progress while progressing.
- *
- * For example, the snippet
- *
- *     var parser = letter() & word().star();
- *     progress(parser).parse('f123');
- *
- * produces the following output:
- *
- *     * Instance of 'SequenceParser'
- *     * Instance of 'CharacterParser'[letter expected]
- *     ** Instance of 'PossessiveRepeatingParser'[0..*]
- *     ** Instance of 'CharacterParser'[letter or digit expected]
- *     *** Instance of 'CharacterParser'[letter or digit expected]
- *     **** Instance of 'CharacterParser'[letter or digit expected]
- *     ***** Instance of 'CharacterParser'[letter or digit expected]
- *
- * Jumps backwards mean that the parser is back-tracking. Often choices can
- * be reordered to such expensive parses.
- */
-Parser progress(Parser parser, [OutputHandler output = print]) {
-  return transformParser(parser, (each) {
-    return new ContinuationParser(each, (continuation, context) {
-      output('${_repeat(1 + context.position, '*')} $each');
-      return continuation(context);
-    });
-  });
-}