Recursive descent parser: Difference between revisions

Revision as of 08:30, 12 October 2018

Revision as of 09:04, 12 November 2018

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===C implementation===

What follows is ana implementation of a recursive descent parser for the above language in [[C (programming language)|C]]. The parser reads in source code, and exits with an error message if the code fails to parse, exiting silently if the code parses correctly.

Notice how closely the predictive parser below mirrors the grammar above. There is a procedure for each nonterminal in the grammar. Parsing descends in a top-down manner, until the final nonterminal has been processed. The program fragment depends on a global variable, ''sym'', which contains the current symbol from the input, and the function ''nextsym'', which updates ''sym'' when called.