.\" Copyright (c) 1989, 1990 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Robert Paul Corbett.
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.\"	from: @(#)yacc.1	5.7 (Berkeley) 7/30/91
.\"	$Id: yacc.1,v 1.2 1996/01/11 17:52:34 deraadt Exp $
.\"
.Dd July 30, 1991
.Dt YACC 1
.Os
.Sh NAME
.Nm yacc
.Nd an
.Tn LALR(1)
parser generator
.Sh SYNOPSIS
.Nm yacc
.Op Fl dlrtv
.Op Fl b Ar prefix
.Op Fl p Ar symbol_prefix
.Ar filename
.Sh DESCRIPTION
.Nm Yacc
reads the grammar specification in the file
.Ar filename
and generates an
.Tn LR(1)
parser for it.
The parsers consist of a set of
.Tn LALR(1)
parsing tables and a driver routine
written in the C programming language.
.Nm Yacc
normally writes the parse tables and the driver routine to the file
.Pa y.tab.c .
.Pp
The following options are available:
.Bl -tag -width Ar
.It Fl b Ar prefix
The
.Fl b
option changes the prefix prepended to the output file names to
the string denoted by
.Ar prefix .
The default prefix is the character
.Ar y .
.It Fl d
The
.Fl d
option causes the header file
.Pa y.tab.h
to be written.
.It Fl l
If the
.Fl l
option is not specified,
.Nm yacc
will insert #line directives in the generated code.
The #line directives let the C compiler relate errors in the
generated code to the user's original code.
If the
.Fl l
option is specified,
.Nm yacc
will not insert the #line directives.
#line directives specified by the user will be retained.
.It Fl p Ar symbol_prefix
The
.Fl p
option changes the prefix prepended to yacc-generated symbols to
the string denoted by
.Ar symbol_prefix .
The default prefix is the string
.Ar yy .
.It Fl r
The
.Fl r
option causes
.Nm yacc
to produce separate files for code and tables.
The code file is named
.Pa y.code.c ,
and the tables file is named
.Pa y.tab.c .
.It Fl t
The
.Fl t
option changes the preprocessor directives generated by
.Nm yacc
so that debugging statements will be incorporated in the compiled code.
.It Fl v
The
.Fl v
option causes a human-readable description of the generated parser to
be written to the file
.Pa y.output .
.Pp
.Sh ENVIRONMENT
The following environment variable is referenced by
.Nm yacc :
.Bl -tag -width TMPDIR
.It Ev TMPDIR
If the environment variable
.Ev TMPDIR
is set, the string denoted by
.Ev TMPDIR
will be used as the name of the directory where the temporary
files are created.
.El
.Sh TABLES
The names of the tables generated by this version of
.Nm yacc
are
.Dq yylhs ,
.Dq yylen ,
.Dq yydefred ,
.Dq yydgoto ,
.Dq yysindex ,
.Dq yyrindex ,
.Dq yygindex ,
.Dq yytable ,
and
.Dq yycheck .
Two additional tables,
.Dq yyname
and
.Dq yyrule ,
are created if
.Dv YYDEBUG
is defined and non-zero.
.Sh FILES
.Bl -tag -width /tmp/yacc.uXXXXXXXX -compact
.It Pa y.code.c
.It Pa y.tab.c
.It Pa y.tab.h
.It Pa y.output
.It Pa /tmp/yacc.aXXXXXX
.It Pa /tmp/yacc.tXXXXXX
.It Pa /tmp/yacc.uXXXXXX
.El
.Sh DIAGNOSTICS
If there are rules that are never reduced, the number of such rules is
written to the standard error.
If there are any
.Tn LALR(1)
conflicts, the number of conflicts is also written
to the standard error.
.\" .Sh SEE ALSO
.\" .Xr yyfix 1
.Sh STANDARDS
The
.Nm yacc
utility conforms to
.St -p1003.2 .