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Approximating Context-Free Grammars for Parsing and Verification

Abstract : Programming language developers are blessed with the availability of efficient, powerful tools for parser generation. But even with automated help, the implementation of a parser remains often overly complex.

Although programs should convey an unambiguous meaning, the parsers produced for their syntax, specified by a context-free grammar, are most often nondeterministic, and even ambiguous. Facing the limitations of traditional deterministic parsers, developers have embraced general parsing techniques, capable of exploring every nondeterministic choice, but offering no unambiguity warranty. The real challenge in parser development lies then in the proper identification and treatment of ambiguities---but these issues are undecidable.

The grammar approximation technique discussed in the thesis is applied to nondeterminism and ambiguity issues in two different ways. The first application is the generation of noncanonical parsers, less prone to nondeterminism, mostly thanks to their ability to exploit an unbounded context-free language as right context to guide their decision. Such parsers enforce the unambiguity of the grammar, and furthermore warrant a linear time parsing complexity. The second application is ambiguity detection in itself, with the insurance that a grammar reported as unambiguous is actually so, whatever level of approximation we might choose.
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Contributor : Sylvain Schmitz <>
Submitted on : Tuesday, April 8, 2008 - 1:39:40 PM
Last modification on : Monday, October 12, 2020 - 10:30:27 AM
Long-term archiving on: : Friday, September 28, 2012 - 12:25:30 PM


  • HAL Id : tel-00271168, version 1



Sylvain Schmitz. Approximating Context-Free Grammars for Parsing and Verification. Software Engineering [cs.SE]. Université Nice Sophia Antipolis, 2007. English. ⟨tel-00271168⟩



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