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.\" 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
.\"
.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 o Ar output_file
.Op Fl p Ar symbol_prefix
.Ar filename
.Sh DESCRIPTION
.Nm
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
normally writes the parse tables and the driver routine to the file
.Pa y.tab.c .
.Pp
The options are as follows:
.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
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
will not insert the #line directives.
#line directives specified by the user will be retained.
.It Fl o Ar output_file
The
.Fl o
option specifies an explicit name for the parser's output file name instead
of the default.
The names of the other output files are constructed from
.Pa output_file
as described under the
.Fl d
and
.Fl v
options.
.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
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
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 .
.Sh ENVIRONMENT
The following environment variables affect the execution of
.Nm yacc :
.Bl -tag -width TMPDIR
.It Ev TMPDIR
Name of directory where temporary files are to be created.
.El
.Sh TABLES
The names of the tables generated by this version of
.Nm
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 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 FILES
.Bl -tag -width /tmp/yacc.uXXXXXXXXXX -compact
.It Pa y.code.c
.It Pa y.tab.c
.It Pa y.tab.h
.It Pa y.output
.It Pa /tmp/yacc.aXXXXXXXXXX
.It Pa /tmp/yacc.tXXXXXXXXXX
.It Pa /tmp/yacc.uXXXXXXXXXX
.El
.Sh SEE ALSO
.Xr yyfix 1
.Sh STANDARDS
The
.Nm
utility conforms to
.St -p1003.2 .