yacc(1) 							   User Commands							   yacc(1)

NAME

       yacc - 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
       analyzer  program,  yylex(),  as  well as main() and yyerror(), an error handling 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 specified), will be changed to file_pre-
		       fix.tab.c, file_prefix.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  func-
		       tions  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 notational 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  compi-
		       lation  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 symbol. If YYDEBUG has a non-zero value,  then  the
		       debugging 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 description of the parsing tables and a report on conflicts generated by ambi-
		       guities in the grammar.

       -V	       Prints on the standard error output the version information 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
       functions 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
", 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_MES-
       SAGES, 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 ALSO

       cc(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)