yacc(1)  UNIX System V(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.

FILES




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


      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)
      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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