A Simple, Possibly Correct LR Parser for C11
Résumé
The syntax of the C programming language is described in the C11 standard by an ambiguous context-free grammar, accompanied with English prose that describes the concept of " scope " and indicates how certain ambiguous code fragments should be interpreted. Based on these elements, the problem of implementing a compliant C11 parser is not entirely trivial. We review the main sources of difficulty and describe a relatively simple solution to the problem. Our solution employs the well-known technique of combining an LALR(1) parser with a " lexical feedback " mechanism. It draws on folklore knowledge and adds several original aspects , including: a twist on lexical feedback that allows a smooth interaction with lookahead; a simplified and powerful treatment of scopes; and a few amendments in the grammar. Although not formally verified, our parser avoids several pitfalls that other implementations have fallen prey to. We believe that its simplicity, its mostly-declarative nature, and its high similarity with the C11 grammar are strong informal arguments in favor of its correctness. Our parser is accompanied with a small suite of " tricky " C11 programs. We hope that it may serve as a reference or a starting point in the implementation of compilers and analysis tools.
Domaines
Langage de programmation [cs.PL]Origine | Fichiers produits par l'(les) auteur(s) |
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