yacc(1) User Commands yacc(1)NAMEyacc - yet another compiler-compiler
SYNOPSIS
/usr/ccs/bin/yacc [-dltVv] [-b file_prefix] [ -Q
[y | n] ] [-P parser] [-p sym_prefix] file
DESCRIPTION
The yacc command converts a context-free grammar into a set of tables
for a simple automaton that executes an LALR(1) parsing algorithm. The
grammar may be ambiguous. Specified precedence rules are used to break
ambiguities.
The output file, y.tab.c, must be compiled by the C compiler to produce
a function yyparse(). This program must be loaded with the lexical ana‐
lyzer program, yylex(), as well as main() and yyerror(), an error han‐
dling routine. These routines must be supplied by the user. The lex(1)
command is useful for creating lexical analyzers usable by yacc.
OPTIONS
The following options are supported:
-b file_prefix Uses file_prefix instead of y as the prefix for all
output files. The code file y.tab.c, the header file
y.tab.h (created when -d is specified), and the
description file y.output (created when -v is speci‐
fied), will be changed to file_prefix.tab.c, file_pre‐
fix.tab.h, and file_prefix.output, respectively.
-d Generates the file y.tab.h with the #define statements
that associate the yacc user-assigned "token codes"
with the user-declared "token names". This association
allows source files other than y.tab.c to access the
token codes.
-l Specifies that the code produced in y.tab.c will not
contain any #line constructs. This option should only
be used after the grammar and the associated actions
are fully debugged.
-p sym_prefix Uses sym_prefix instead of yy as the prefix for all
external names produced by yacc. The names affected
include the functions yyparse(), yylex() and yyerror(),
and the variables yylval, yychar and yydebug. (In the
remainder of this section, the six symbols cited are
referenced using their default names only as a nota‐
tional convenience.) Local names may also be affected
by the -p option. However, the -p option does not
affect #define symbols generated by yacc.
-P parser Allows you to specify the parser of your choice instead
of /usr/ccs/bin/yaccpar. For example, you can specify:
example% yacc-P ~/myparser parser.y
-Q[y|n] The -Qy option puts the version stamping information in
y.tab.c. This allows you to know what version of yacc
built the file. The -Qn option (the default) writes no
version information.
-t Compiles runtime debugging code by default. Runtime
debugging code is always generated in y.tab.c under
conditional compilation control. By default, this code
is not included when y.tab.c is compiled. Whether or
not the -t option is used, the runtime debugging code
is under the control of YYDEBUG , a preprocessor sym‐
bol. If YYDEBUG has a non-zero value, then the debug‐
ging code is included. If its value is 0, 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.
-v Prepares the file y.output, which contains a descrip‐
tion of the parsing tables and a report on conflicts
generated by ambiguities in the grammar.
-V Prints on the standard error output the version infor‐
mation for yacc.
OPERANDS
The following operand is required:
file A path name of a file containing instructions for which a
parser is to be created.
EXAMPLES
Example 1: Accessing the yacc library
Access to the yacc library is obtained with library search operands to
cc. To use the yacc library main:
example% cc y.tab.c -ly
Both the lex library and the yacc library contain main. To access the
yacc main:
example% cc y.tab.c lex.yy.c -ly -ll
This ensures that the yacc library is searched first, so that its main
is used.
The historical yacc libraries have contained two simple functions that
are normally coded by the application programmer. These library func‐
tions are similar to the following code:
#include <locale.h>
int main(void)
{
extern int yyparse();
setlocale(LC_ALL, "");
/* If the following parser is one created by lex, the
application must be careful to ensure that LC_CTYPE
and LC_COLLATE are set to the POSIX locale. */
(void) yyparse();
return (0);
}
#include <stdio.h>
int yyerror(const char *msg)
{
(void) fprintf(stderr, "%s\n", msg);
return (0);
}
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables
that affect the execution of yacc: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
and NLSPATH.
yacc can handle characters from EUC primary and supplementary codesets
as one-token symbols. EUC codes may only be single character quoted
terminal symbols. yacc expects yylex() to return a wide character
(wchar_t) value for these one-token symbols.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
FILES
y.output state transitions of the generated parser
y.tab.c source code of the generated parser
y.tab.h header file for the generated parser
yacc.acts temporary file
yacc.debug temporary file
yacc.tmp temporary file
yaccpar parser prototype for C programs
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWbtool │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOcc(1B), lex(1), attributes(5), environ(5), standards(5)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
y.output file. Similarly, if some rules are not reachable from the
start symbol, this instance is also reported.
NOTES
Because file names are fixed, at most one yacc process can be active in
a given directory at a given time.
Users are encouraged to avoid using '$' as part of any identifier name.
SunOS 5.10 20 Dec 1996 yacc(1)
