A New Normal-Form Theorem for Context-Free Phrase Structure Grammars
Journal of the ACM (JACM)
Journal of the ACM (JACM)
Weak and Mixed Strategy Precedence Parsing
Journal of the ACM (JACM)
A Formalization of Transition Diagram Systems
Journal of the ACM (JACM)
Foundations of Fast Communication via XML
Annals of Software Engineering
ACM SIGPLAN Notices
SuperC: parsing all of C by taming the preprocessor
Proceedings of the 33rd ACM SIGPLAN conference on Programming Language Design and Implementation
Proceedings of the 26th annual ACM symposium on User interface software and technology
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The class of context free grammars that can be deterministically parsed in a top down manner with a fixed amount of look-ahead is investigated. These grammars, called LL(k) grammars where k is the amount of look-ahead are first defined and a procedure is given for determining if a context free grammar is LL(k) for a given value of k. It is shown that &egr;-rules can be eliminated from an LL(k) grammar, at the cost of increasing the value of k by one, and a description is given of a canonical pushdown machine for recognizing LL(k) languages. It is shown that for each value of k there are LL(k+l) languages that are not LL(k) languages. It is shown that the equivalence problem is decidable for LL(k) grammars. Additional properties are also given.