NAME

yacc − yet another compiler-compiler: parsing program generator

SYNOPSIS

yacc [ −dv ] grammar

DESCRIPTION

yacc converts a context−free grammar into a set of tables for a simple automaton which executes an LR(1) parsing algorithm.  The grammar may be ambiguous, in which case specified precedence rules may be used to break those ambiguities. 

The output file, y.tab.c, must be compiled by the C compiler to produce a function named yyparse(). The yyparse() function must be loaded with the lexical analyzer yylex(), as well as main() and the error handling routine yyerror(). These routines must be supplied by the user; lex(1) is useful for creating lexical analyzers usable by yacc−produced parsers. 

OPTIONS

−d Generate the file y.tab.h with the define statements that associate the yacc−assigned “token codes” with the user−declared “token names” so that source files other than y.tab.c can access the token codes. 

−v Prepare the file y.output containing a description of the parsing tables and a report on conflicts generated by ambiguities in the grammar. 

FILES

y.output description of parsing tables and conflict report

y.tab.c output parser

y.tab.h defines for token names

yacc.tmp, yacc.acts temporary files

/usr/lib/yaccpar parser prototype for C programs

SEE ALSO

lex(1)

Programming Utilities and Libraries
LR Parsing by A. V. Aho and S. C. Johnson, Computing Surveys, June, 1974

DIAGNOSTICS

The number of reduce−reduce and shift−reduce conflicts is reported on the standard output; a more detailed report is found in the y.output file.  Similarly, it is also reported if some rules are not reachable from the start symbol. 

BUGS

Because file names are fixed, no more than one yacc process should be active in a given directory at a time. 

Sun Release 4.0  —  Last change: 26 March 1989