YACC(1) 						      General Commands Manual							   YACC(1)

NAME

       yacc - yet another compiler-compiler

SYNOPSIS

       yacc [ -vd ] 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; specified precedence rules are used to break ambiguities.

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

       If the -v flag is given, the file y.output is prepared, which contains a description of the parsing tables and a report on conflicts gener-
       ated by ambiguities in the grammar.

       If  the	-d  flag is used, the file y.tab.h is generated with the define statements that associate the yacc-assigned `token codes' with the
       user-declared `token names'.  This allows source files other than y.tab.c to access the token codes.

FILES

       y.output
       y.tab.c
       y.tab.h		   defines for token names
       yacc.tmp, yacc.acts temporary files
       /usr/lib/yaccpar    parser prototype for C programs
       /lib/liby.a	   library with default `main' and `yyerror'

SEE ALSO

       lex(1)
       LR Parsing by A. V. Aho and S. C. Johnson, Computing Surveys, June, 1974.
       YACC - Yet Another Compiler Compiler by S. C. Johnson.

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, if some rules are not reachable from the start symbol, this is also reported.

BUGS

       Because file names are fixed, at most one yacc process can be active in a given directory at a time.

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