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.TH YACC 1 "December 10, 1989"

.UC 6

.SH NAME

Yacc \- an LALR(1) parser generator

.SH SYNOPSIS

.B yacc [ -dltv ] [ -b

.I 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.

.PP

The following options are available:

.RS

.TP

\fB-b \fIprefix\fR

The

.B -b

option changes the prefix prepended to the output file names to

the string denoted by

.IR 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.

.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

.B -t

The

.B -t

option will change 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.

.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.

.SH TABLES

There is a program \fI:yyfix\fR

that extracts tables from \fIyacc\fR-generated

files.

The program takes the names of the tables as its command-line arguments.

The names of the tables generated by this version of

.I yacc

are

.IR yylhs,

.IR yylen,

.IR yydefred,

.IR yydgoto,

.IR yysindex,

.IR yyrindex,

.IR yygindex,

.IR yytable,

and

.IR yycheck.

Two additional tables,

.I yyname

and

.I yyrule,

are created if YYDEBUG is defined and nonzero.

.SH FILES

.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

.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.

