Full visual debugging facilities for look-ahead productions

Detlef Meyer-Eltz <Meyer-Eltz@t-online.de>
Tue, 6 Nov 2007 14:05:30 +0100

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Full visual debugging facilities for look-ahead productions Meyer-Eltz@t-online.de (Detlef Meyer-Eltz) (2007-11-06)
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From: Detlef Meyer-Eltz <Meyer-Eltz@t-online.de>
Newsgroups: comp.compilers
Date: Tue, 6 Nov 2007 14:05:30 +0100
Organization: Compilers Central
Keywords: tools, debug, available
Posted-Date: 06 Nov 2007 10:42:11 EST

TextTransformer 1.4.0 with new debugging facilities has been released.
TextTransformer is a Windows IDE to construct, debug and execute
parsers and translators. You can download the program from:


New in version 1.4.0

1. Now look-ahead productions (*) can be debugged as well, just like
      ordinary productions. A special button or shortcut starts
      look-ahead debugging, afterwards the same commands can be used to
      single step over or into productions, as in the mainstream
      debugger. This even works in the staggered case, where other
      look-ahead productions are used inside of the first one; and so on.

(*) Explanation to look-ahead productions: For disambiguation of
alternatives, a tentative parse of the input is possible, using the
already existing productions. In this mode no semantic actions are
performed, instead the productions return an success/failure value,
which allows to skip inappropriate alternatives. This is very similar
to GLR parsing.

2. Now it's also possible to step backwards in the debugger, from a
      breakpoint or error condition. This backtrace allows to find out
      how this state was reached, without restarting the parser, and
      eliminates the need for writing specialized test cases, which
      otherwise may be required to reproduce a certain error condition.

3. The variable-inspector now shows all members of a container
      variable. A double click on a node member shows the entire subtree,
      linked to this node.

4. Subtrees can be opened and closed in the tree display, and the root
      of the tree can be moved to the present parents root.

5. Many more small improvements and bug fixes.

These new debugging facilities were developed in connection with a big
project carried out successfully: a parser for the programming
language C++ has been built for the preparatorily translation of
approx. 120000 lines of source code of a company software into Java

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