Navegando por Autor "Maidl, André Murbach"

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Error reporting in Parsing Expression Grammars
(Elsevier, 2016-12-15) Medeiros, Sérgio Queiroz de; Maidl, André Murbach; Mascarenhas, Fabio; Ierusalimschy, Roberto
Parsing Expression Grammars (PEGs) describe top-down parsers. Unfortunately, the error-reporting techniques used in conventional top-down parsers do not directly apply to parsers based on Parsin Expression Grammars (PEGs), so they have to be somehow simulated. While the PEG formalism has no account of semantic actions, actual PEG implementations add them, and we show how to simula-te an error-reporting heuristic through these semantic actions. We also propose a complementary error reporting strategy that may lead to better error messages: labeled failures. This approach is inspired by exception handling of programming languages, and lets a PEG define different kinds of failure, with each ordered choice operator specifying which kinds it catches. Labeled failures give a way to annotate grammars for better error reporting, to express some of the error reporting strategies used by deterministic parser combinators, and to encode predictive top-down parsing in a PEG. © 2016 Elsevier B.V. All rights reserved.

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