Scannerless NSLR(1) Parsing of Programming Languages

Abstract

The disadvantages of traditional two-phase parsing (a scanner phase preprocessing input for a parser phase) are discussed. We present metalanguage enhancements for context-free grammars that allow the syntax of programming languages to be completely described in a single grammar. The enhancements consist of two new grammar rules, the exclusion rule, and the adjacency-restriction rule. We also present parser construction techniques for building parsers from these enhanced grammars, that eliminate the need for a scanner phase.