.\"	%W%	%R% (Berkeley) %E%
.\"
.TH YACC 1 "July\ 15,\ 1990"
.UC 6
.SH NAME
Yacc \- an LALR(1) parser generator
.SH SYNOPSIS
.B yacc [ -dlrstv ] [ -b
.I file_prefix
.B ] [ -p
.I symbol_prefix
.B ]
.I filename
.SH DESCRIPTION
.I Yacc
reads the grammar specification in the file
.I filename
and generates an LR(1) parser for it.
The parsers consist of a set of LALR(1) parsing tables and a driver routine
written in the C programming language.
.I Yacc
normally writes the parse tables and the driver routine to the file
.IR y.tab.c
The same file name is usualy used on Win9X if LFN support is available.
On Win9X with LFN support available, you can control the type of
.IR tab
.IR extension
.IR separator
you prefer to use by seting or omiting the
.B -s
command-line option. On Win9X with LFN support available and an omited
.B -s
option a dot is used as extension separator in all file names and you will
get the same file names as on a posix system.
On plain DOS the 
.B -s
option is ignored.
On Win9X with LFN support available, you can force the use of
.IR y_tab.c
as file name if you specify the
.B -s
option. On plain DOS
.IR y_tab.c
is always used as file name.
.PP
The following options are available:
.RS
.TP
\fB-b \fIfile_prefix\fR
The
.B -b
option changes the prefix prepended to the output file names to
the string denoted by
.IR file_prefix.
The default prefix is the character
.IR y.
.TP
.B -d
The \fB-d\fR option causes the header file
.IR y.tab.h
to be written.
The
.IR y.tab.h
file name is also used on Win9X if LFN support is available
and the
.B -s
option has been omited.
On plain DOS or Win9X with LFN support available and with the
.B -s
option specified,
.IR y_tab.h
will be used as the file name.
.TP
.B -l
If the
.B -l
option is not specified,
.I 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 \fB-l\fR option is specified,
.I yacc
will not insert the #line directives.
#line directives specified by the user will be retained.
.TP
\fB-p \fIsymbol_prefix\fR
The
.B -p
option changes the prefix prepended to yacc-generated symbols to
the string denoted by
.IR symbol_prefix.
The default prefix is the string
.IR yy.
.TP
.B -r
The
.B -r
option causes
.I yacc
to produce separate files for code and tables.  The code file
is named
.IR y.code.c
and the tables file is named
.IR y.tab.c.
The
.IR y.code.c
and
.IR y.tab.c
file names are also used on Win9X if LFN support is available and the
.B -s
option has been omited.
On plain DOS or Win9X with LFN support available
.IR y_code.c
and
.IR y_tab.c
are used as file name if the
.B -s
option has been specified.
.TP
.B -s
The
.B -s
is a DJGPP specific option that allows the user to choose the
type of prefered
.IR tab
.IR extension
.IR separator.
The
.B -s
option is ignored on plain DOS and Win9X without LFN support.
In this case always file names with an underscore as
.IR tab
.IR extension
.IR separator
will be used.
On Win9X with LFN support available, if the
.B -s
option is specified, always file names with an undersore as
.IR tab
.IR extension
.IR separator
will be used.
On Win9X with LFN support available, if the
.B -s
option is omited, always file names with a dot as
.IR tab
.IR extension
.IR separator
will be used.
.TP
.B -t
The
.B -t
option changes the preprocessor directives generated by
.I yacc
so that debugging statements will be incorporated in the compiled code.
.TP
.B -v
The
.B -v
option causes a human-readable description of the generated parser to
be written to the file
.IR y.output.
The
.IR y.output
file name is also used on Win9X if LFN support is available and the
.B -s
option has not been specified.
On plain DOS or Win9X with LFN support available
.IR y.out
is used as file name if the
.B -s
option has been specified.
.RE
.PP
If the environment variable TMPDIR is set, the string denoted by
TMPDIR will be used as the name of the directory where the temporary
files are created.
On MS-DOS the string denoted by one of the following environment variables TMPDIR, TMP
or TEMP (in this order) will be used as the name of the directory where the temporary
files are created. If non of them are set, the working directory will be used.
.SH FILES
.IR y.code.c
.br
.IR y.tab.c
.br
.IR y.tab.h
.br
.IR y.output
.br
.IR /tmp/yacc.aXXXXXX
.br
.IR /tmp/yacc.tXXXXXX
.br
.IR /tmp/yacc.uXXXXXX


On Win9X with LFN support available and the
.B -s
option omited the following files will be generated:

.IR y.code.c
.br
.IR y.tab.c
.br
.IR y.tab.h
.br
.IR y.output
.br
.IR $TMPDIR/yaXXXXXX
.br
.IR $TMPDIR/ytXXXXXX
.br
.IR $TMPDIR/yuXXXXXX

On plain DOS and Win9X with LFN support available and the
.B -s
option specified the following files will be generated:

.IR y_code.c
.br
.IR y_tab.c
.br
.IR y_tab.h
.br
.IR y.out
.br
.IR $TMPDIR/yaXXXXXX
.br
.IR $TMPDIR/ytXXXXXX
.br
.IR $TMPDIR/yuXXXXXX

$TMPDIR denotes the value of one of the environment variables TMPDIR, TMP or TEMP or the working
directory if non of them are set.

.SH DIAGNOSTICS
If there are rules that are never reduced, the number of such rules is
reported on standard error.
If there are any LALR(1) conflicts, the number of conflicts is reported
on standard error.