yacc(1)       (Extended Software Generation System Utilities)       yacc(1)


   NAME
         yacc - yet another compiler-compiler

   SYNOPSIS
         yacc [-vVdlt] [-Q[y|n]] 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 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;
         the lex(1) command is useful for creating lexical analyzers usable by
         yacc.

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

         -d       Generates the file y.tab.h with the #define statements that
                  associate the yacc-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.

         -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 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.

         -V       Prints on the standard error output the version information
                  for yacc.



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   yacc(1)       (Extended Software Generation System Utilities)       yacc(1)


   FILES
         y.output
         y.tab.c
         y.tab.h             defines for token names
         yacc.tmp,
         yacc.debug, yacc.acts
                             temporary files
         LIBDIR/yaccpar      parser prototype for C programs
         LIBDIR              usually /usr/ccs/lib

   SEE ALSO
         lex(1).
         See the ``yacc'' chapter in the programmer's Guide: ANSI C and
         Programming Support Tools.

   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.





























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