yacc(1)                                                   yacc(1)



NAME
     yacc - compiles compilers (yet another compiler-compiler)

SYNOPSIS
     yacc [-d] [-l] [-t] [-v] grammar

ARGUMENTS
     -d   Generates the y.tab.h file 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.

     grammar
          Specifies the data that will be converted by yacc.

     -l   Prevents the code produced in y.tab.c from containing
          any #line constructs.  This option should only be used
          after the grammar and the associated actions are fully
          debugged.

     -t   Compiles the runtime debugging code.

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

DESCRIPTION
     yacc converts a context-free grammar into a set of tables
     for a simple automaton which executes an lr 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 routine is useful for
     creating lexical analyzers usable by yacc.

     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 nonzero 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.





January 1992                                                    1

yacc(1)                                                   yacc(1)



EXAMPLES
     To process a file called file1.y in yacc format, enter:

        yacc file1.y


STATUS MESSAGES AND VALUES
     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.

LIMITATIONS
     Because filenames are fixed, only one yacc process can be
     active in a given directory at a time.

FILES
     /bin/yacc
          Executable file
     y.output
          Output file
     y.tab.c
          File
     y.tab.h
          File
     yacc.tmp
          Temporary file
     yacc.debug
          Temporary file
     yacc.acts
          Temporary file
     /usr/lib/yaccpar
          Temporary file

SEE ALSO
     lex(1)

     malloc(3X) in A/UX Programmer's Reference

     The yacc reference in A/UX Programming Languages and Tools,
     Volume 2













2                                                    January 1992