minix/external/bsd/byacc/bin/yacc.1

.\"	$NetBSD: yacc.1,v 1.4 2011/09/10 21:38:59 christos Exp $
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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
.\"	from: Id: yacc.1,v 1.12 2011/09/08 00:40:44 tom Exp
.\"	$NetBSD: yacc.1,v 1.4 2011/09/10 21:38:59 christos Exp $
.\"
.Dd September 7, 2011
.Dt YACC 1
.Os
.Sh NAME
.Nm yacc
.Nd an
.Tn LALR(1)
parser generator
.Sh SYNOPSIS
.Nm
.Op Fl dgilPrtVv
.Op Fl b Ar prefix
.Op Fl o Ar outputfile
.Op Fl p Ar symbol_prefix
.Ar filename
.Sh DESCRIPTION
.Nm
reads the grammar specification in the file
.Ar filename
and generates an
.Tn LALR(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 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 contains #define's for the token identifiers.
.It Fl g
The
.Fl g
option causes a graphical description of the generated
.Tn LALR(1)
parser to be written to the file
.Pa y.dot
in graphviz format, ready to be processed by
.Xr dot 1 .
.It Fl i
The 
.Fl i
option causes a supplementary header file
.Pa y.tab.i
to be written.
It contains extern declarations
and supplementary #define's as needed to map the conventional
.Nm
yy-prefixed names to whatever the
.Fl p
option may specify.
The code file, e.g., 
.Pa y.tab.c
is modified to #include this file
as well as the
.Pa y.tab.h
file, enforcing consistent usage of the symbols defined in those files.
The supplementary header file makes it simpler to separate compilation
of lex- and yacc-files.
.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 outputfile
The
.Fl o
option specifies an explicit output file name should be used instead
of the default.
.It Fl P
The
.Fl P
options instructs
.Nm
to create a reentrant parser, like
.Dq %pure-parser
does.
.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 prints the version number to the standard output.
.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 .
.El
.Sh EXTENSIONS
.Nm
provides some extensions for compatibility with 
.Xr bison 1
and other implementations
of 
.Nm :
.Pp
.Bl -tag -width "%expect-rr number" -compact
.It Dv %expect Ar number
Tell
.Nm
the expected number of shift/reduce conflicts.
That makes it only report the number if it differs.
.It Dv %expect-rr Ar number
Tell 
.Nm
the expected number of reduce/reduce conflicts.
That makes it only report the number if it differs.
This is (unlike
.Xr bison 1 )
allowable in
.Tn LALR(1)
parsers.
.It Dv %lex-param Ar { Ar argument-declaration Ar }
By default, the lexer accepts no parameters, e.g., 
.Fn yylex .
Use this directive to add parameter declarations for your customized lexer.
.It Dv %parse-param Ar { Ar argument-declaration Ar }
By default, the parser accepts no parameters, e.g.,
.Fn yyparse .
Use this directive to add parameter declarations for your customized parser.
.It Dv %pure-parser
Most variables (other than 
.Fa yydebug
and
.Fa yynerrs )
are allocated on the stack within
.Fn yyparse ,
making the parser reasonably reentrant.
.El
.Sh ENVIRONMENT
The following environment variable is referenced by
.Nm :
.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
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
utility conforms to
.St -p1003.2 .