YACC(1) | General Commands Manual | YACC(1) |
yacc
— an LALR(1)
parser generator
yacc |
[-dlrtv ] [-b
file_prefix] [-o
output_file] [-p
symbol_prefix] file |
yacc
reads the grammar specification in
file 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. yacc
normally writes the
parse tables and the driver routine to the file
y.tab.c.
The options are as follows:
-b
file_prefix-b
option changes the prefix prepended to the
output file names to the string denoted by
file_prefix. The default prefix is the character
y.-d
-d
option causes the header file
y.tab.h to be written.-l
-l
option is not specified,
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
-l
option is specified,
yacc
will not insert the #line directives. #line
directives specified by the user will be retained.-o
output_file-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 output_file as
described under the -d
and
-v
options.-p
symbol_prefix-p
option changes the prefix prepended to
yacc-generated symbols to the string denoted by
symbol_prefix. The default prefix is the string
yy.-r
-r
option causes yacc
to produce separate files for code and tables. The code file is named
y.code.c, and the tables file is named
y.tab.c.-t
-t
option changes the preprocessor directives
generated by yacc
so that debugging statements
will be incorporated in the compiled code.-v
-v
option causes a human-readable description
of the generated parser to be written to the file
y.output.The names of the tables generated by this version of
yacc
are “yylhs”,
“yylen”, “yydefred”, “yydgoto”,
“yysindex”, “yyrindex”,
“yygindex”, “yytable”, and
“yycheck”. Two additional tables, “yyname” and
“yyrule”, are created if YYDEBUG
is
defined and non-zero.
The yacc
utility exits 0 on
success, and >0 if an error occurs.
If there are rules that are never reduced, the number of such rules is written to the standard error. If there are any LALR(1) conflicts, the number of conflicts is also written to the standard error.
S. C. Johnson, Yacc — Yet Another Compiler-Compiler, AT&T Bell Laboratories, Computing Science Technical Report, 32, July 1975.
F. DeRemer and T. J. Pennello, Efficient Computation of LALR(1) Look-Ahead Sets, TOPLAS, Issue 4, Volume 4, pp. 615–649, 1982.
The yacc
utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification, though its presence is optional.
The flags [-or
] are extensions to that
specification.
yacc
was originally developed at AT&T
by Stephen C. Johnson.
Berkeley yacc
was originally developed
using PCC on a VAX with the intent of being as compatible as possible with
AT&T UNIX yacc
. Much is
owed to the unflagging efforts of Keith Bostic. His badgering kept me
working on yacc
long after I was ready to quit.
Berkeley yacc
is based on the excellent
algorithm for computing LALR(1) lookaheads developed by Tom
Pennello and Frank DeRemer. The algorithm is
described in their almost impenetrable article in TOPLAS (see above).
Finally, much credit must go to those who pointed out deficiencies of earlier releases. Among the most prolific contributors were Benson I. Margulies, Dave Gentzel, Antoine Verheijen, Peter S. Housel, Dale Smith, Ozan Yigit, John Campbell, Bill Sommerfeld, Paul Hilfinger, Gary Bridgewater, Dave Bakken, Dan Lanciani, Richard Sargent, and Parag Patel.
The yacc
utility was written by
Robert Corbett.
March 8, 2021 | OpenBSD-current |