yacc(1) — AIX PS/2 1.2.1



YACC(1,C)                   AIX Commands Reference                    YACC(1,C)



-------------------------------------------------------------------------------
yacc



PURPOSE

Generates an LR parsing program from input consisting of a context-free grammar
specification.

SYNTAX


        +-----------+
yacc ---| +-------+ |-- grammar --|
        +-| -v -d |-+
         ^| -l -s ||
         || -t    ||
         |+-------+|
         +---------+


Note:  This command does not have MBCS support.

DESCRIPTION

The yacc command converts a context-free grammar into a set of tables for a
simple automaton that executes an LR(1) parsing algorithm.  The grammar can be
ambiguous; specified precedence rules are used to break ambiguities.

You must compile the output file, y.tab.c, with a C Language compiler to
produce a function yyparse.  This function must be loaded with the lexical
analyzer function yylex, as well as main and yyerror, an error-handling routine
(you must provide these routines).  The lex command is useful for creating
lexical analyzers usable by yacc.

For more detailed discussion of yacc and its operations, see AIX Operating
System Programming Tools and Interfaces.

FLAGS

-d Produces the file y.tab.h.  This contains the #define statements that
   associate the yacc-assigned token codes with your token names.  This allows
   source files other than y.tab.c to access the token codes by including this
   header file.

-l Does not include any #line constructs in y.tab.c.  Use this only after the
   grammar and associated actions are fully debugged.

-s Breaks the yyparse function into several smaller functions.  Since its size
   is somewhat proportional to that of the grammar, it is possible for yyparse
   to become too large to compile, optimize, or execute efficiently.



Processed November 8, 1990         YACC(1,C)                                  1



YACC(1,C)                   AIX Commands Reference                    YACC(1,C)




-t Compiles run-time debugging code.  By default, this code is not included
   when y.tab.c is compiled.  However, the run-time debugging code is under the
   control of YYDEBUG, a global variable for the cc command preprocessor.  If
   YYDEBUG has a nonzero value, the C compiler (cc) includes the debugging
   code, whether the -t flag was used.  Without compiling this code, yyparse
   has a faster operating speed.

-v Prepares the file y.output.  It contains a readable description of the
   parsing tables and a report on conflicts generated by grammar ambiguities.

FILES

y.output
y.tab.c
y.tab.h                Definitions for token names.
yacc.tmp,
yacc.debug             Temporary file.
yacc.acts              Temporary file.
/usr/lib/yaccpar       Parser prototype for C programs.

RELATED INFORMATION

See the following command:  "lex."

See the description of yacc in AIX Operating System Programming Tools and
Interfaces.




























Processed November 8, 1990         YACC(1,C)                                  2

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