


      YACC(1)                     (UNIX 5.0)                    YACC(1)



      NAME
           yacc - yet another compiler-compiler

      SYNTAX
           yacc [ -vdlt ] grammar

      DESCRIPTION
           Yacc converts a context-free grammar into a set of tables
           for a simple automaton which executes an LR(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 program 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; lex(1) is useful for creating
           lexical analyzers usable by yacc.

           If the -v flag is given, the file y.output is prepared,
           which contains a description of the parsing tables and a
           report on conflicts generated by ambiguities in the grammar.

           If the -d flag is used, the file y.tab.h is generated with
           the #define statements that associate the yacc-assigned
           ``token codes'' with the user-declared ``token names''.
           This allows source files other than y.tab.c to access the
           token codes.

           If the -l flag is given, the code produced in y.tab.c will
           not contain any #line constructs.  This should only be used
           after the grammar and the associated actions are fully
           debugged.

           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.  However, when yacc's
           -t option is used, this debugging code will be compiled by
           default.  Independent of whether the -t option was used, the
           runtime debugging code is under the control of YYDEBUG, a
           pre-processor symbol.  If YYDEBUG 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.

      FILES
           y.output
           y.tab.c
           y.tab.h             defines for token names
           yacc.tmp,
           yacc.debug, yacc.acts    temporary files



      Page 1                                          (73 A2 02MT REV1)






      YACC(1)                     (UNIX 5.0)                    YACC(1)



           /usr/lib/yaccpar    parser prototype for C programs

      SEE ALSO
           lex(1).
           YACC-Yet Another Compiler Compiler in the Programmers Guide
           to ROS.

      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 is also
           reported.

      BUGS
           Because file names are fixed, at most one yacc process can
           be active in a given directory at a time.






































      Page 2                                          (73 A2 02MT REV1)



