pdp11v/usr/man/u_man/man1/yacc.1

.TH YACC 1
.SH NAME
yacc \- yet another compiler-compiler
.SH SYNOPSIS
.B yacc
[
.B \-vdlt
]
grammar
.SH DESCRIPTION
.I Yacc\^
converts a context-free grammar into a set of
tables for a simple automaton which executes an
.SM LR(1)
parsing
algorithm.
The grammar may be ambiguous;
specified precedence rules are used to break ambiguities.
.PP
The output file,
.BR y.tab.c ,
must be compiled by the C compiler
to produce a program
.IR yyparse .
This program must be loaded with the lexical analyzer program,
.IR yylex ,
as well as
.I main\^
and
.IR yyerror ,
an error handling routine.
These routines must be supplied by the user;
.IR lex (1)
is useful for creating lexical analyzers usable by
.IR yacc .
.PP
If the
.B \-v
flag is given, the file
.B y.output
is prepared, which contains a description of the parsing tables
and a report on
conflicts generated by ambiguities in the grammar.
.PP
If the \-\fBd\fR flag is used, the file
.B y.tab.h
is generated with the
.B #define
statements that associate the
.I yacc\c\^
-assigned ``token codes'' with the user-declared ``token names''.
This allows source files other than
.B y.tab.c
to access the token codes.
.PP
If the
.B \-l
flag is given, the code produced in
.B y.tab.c
will \fInot\fR contain any
.B #line
constructs.  This should only be used after the
grammar and the associated actions are fully debugged.
.PP
Runtime debugging code is always generated in
.B y.tab.c
under conditional compilation control.
By default, this code is not included when
.B y.tab.c
is compiled.
However, when
.IR yacc 's
.B \-t
option is used, this debugging code will be compiled by default.
Independent of whether the
.B \-t
option was used, the runtime debugging code is under the control of
.BR \s-1YYDEBUG\s+1 ,
a pre-processor symbol.
If
.B \s-1YYDEBUG\s+1
has a non-zero value, then the debugging code is included.
If its value is zero, then the code will not be included.
The size and execution time of a program produced without the
runtime debugging code will be smaller and slightly faster.
.SH FILES
y.output
.br
y.tab.c
.br
y.tab.h			defines for token names
.br
yacc.tmp,
.br
yacc.debug, yacc.acts	temporary files
.br
/usr/lib/yaccpar	parser prototype for C programs
.br
.SH "SEE ALSO"
lex(1).
.br
.I "\s-1YACC\s+1\-Yet Another Compiler Compiler\^"
in the
.IR "\s-1UNIX\s+1 System Support Tools Guide" .
.SH DIAGNOSTICS
The number of reduce-reduce and shift-reduce conflicts
is reported on the standard error output;
a more detailed report is
found in the
.B y.output
file.
Similarly, if some rules are not reachable from the
start symbol, this is also reported.
.SH BUGS
Because file names are fixed, at most one
.I yacc\^
process can be active in a given directory at
a time.
.\"	@(#)yacc.1	5.2 of 5/18/82