Llun - a high-level debugger for generated parsers

Parser generators such as yacc have been used in a large number of applications, not just those that involve compiler writing. This has meant that these tools are being used increasingly by nonspecialist developers. A consequence of this is that good support is required for debugging a grammar and its generated parser(s). This paper describes Linn, a debugging tool that visualizes the operation of a generated parser at both a high-level and a low-level. Llun is superior to other parser visualization products by virtue of the high-level facilities it offers. The paper describes some of the problems encountered using parser generators, outlines a visualization system which addresses a number of the problems and uses a taxonomy developed by Price to categorize the system. Copyright (C) 2001 John Wiley & Sons, Ltd.