Methods for Computing LALR(k) Lookahead
ACM Transactions on Programming Languages and Systems (TOPLAS)
Efficient Computation of LALR(1) Look-Ahead Sets
ACM Transactions on Programming Languages and Systems (TOPLAS)
Communications of the ACM
Introduction to Formal Language Theory
Introduction to Formal Language Theory
Regular look-ahead and look-back for lr parsers
Regular look-ahead and look-back for lr parsers
Scannerless NSLR(1) parsing of programming languages
PLDI '89 Proceedings of the ACM SIGPLAN 1989 Conference on Programming language design and implementation
Efficient construction of LR(k) states and tables
ACM Transactions on Programming Languages and Systems (TOPLAS)
LL and LR translators need k1 lookahead
ACM SIGPLAN Notices
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We present a practical technique that provides an LR (0) parser with either fixed or arbitrary look-ahead. The construction algorithm is based on certain paths in the LR (0) state diagram, which must be restricted to a maximum length m. The technique determines the amount of look-ahead required, and the user is spared the task of guessing it. Instead, the user provides m. In situations where single symbol look-ahead is sufficient, the corresponding grammar class (called LAR (m )) is identical to the NQLALR (1) class. For practical grammars that require arbitrary look-ahead, the storage requirements typically do not exceed an amount linear in the size of the corresponding LR (0) parser. The technique is shown to work for a practical programming language grammar, and has been used to solve particular cases of the PL/1 keyword problem.