1768	 A Global Parser for Context-Free Phrase Structure Grammars	 An algorithm for analyzing any context-free phrase structure grammar and for generating a program which can then parse any sentence in the language or indicate that the given sentence is invalid is described. The parser is of the top-to-bottom type and is recursive . A number of heuristic procedures whose purpose is to shorten the basic algorithm by quickly ascertaining that certain substrings of the input sentence cannot correspond to the target nonterminal symbols are included. Both the generating algorithm and the parser have been implemented in RCA SNOBOL and have been tested successfully on a number of artificial grammars and on a subset of ALGOL. A number of the routines for extracting data about a grammar such as minimum lengths of N-derivable strings and possible prefixes are given and may be of interest apart from their application in this particular context. parser syntax-directed compiler context-free grammars syntactic analysis translators
