term% cat index.txt 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 ana‐
lyzer 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 generated
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 sym‐
bol, 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.
YACC(1)