yacc(1)                              SysV                              yacc(1)



NAME
     yacc - yet another compiler-compiler

SYNOPSIS
     yacc [-vdlt] [-Xp<path_name>] [-N<secondary><n> ...]  [-p sym_prefix] [-b
     file_prefix] grammar

DESCRIPTION
     yacc converts a context-free grammar into a set of tables for a simple
     automaton which executes an LALR(1) parsing algorithm as described in
     popular compiler-construction literature.  Ambiguous grammar is allowed;
     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.

   Options
     yacc recognizes the following options:

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

          -d             Generate file y.tab.h 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.

          -l             Do not place any #line constructs in code produced in
                         y.tab.c.  Generally, this option should only be used
                         after y.tab.c has compiled successfully, since the
                         #line directives allow the C compiler to give error
                         messages that refer to the yacc source file rather
                         than the y.tab.c file.  This option is useful,
                         however, for symbolic debugging, since some symbolic
                         debuggers may be confused by line numbers that are
                         not in order.

          -t             Compile runtime debugging code (see Debugging below
                         for details).

          -Xp<path_name> Read the skeleton parser source code from path_name
                         instead of /usr/lib/yaccpar.

          -N<secondary><n>
                         Allow the sizes of certain internal yacc tables to be
                         reset.  secondary is one of the letters from the set
                         {Ba m s p n e c l w} and specifies the table; n is
                         the new size.  Tables that can be reset by using
                         secondary letters are as follows:

                              a       a-array size; default is 30000.
                              m       mem array size; default is 30000.
                              s       number of states; default is 1000.
                              p       number of productions; default is 3000.
                              n       number of non-terminals; default is
                                      1000.

                              e       temp-space size; default is 1250.
                              c       name-space size; default is 5000.
                              l       look-ahead set table size; default is
                                      4000.
                              w       working set table size; default is 4000.

          -p sym_prefix  Use sym_prefix instead of yy as the prefix for
                         externally scoped variable and function names
                         produced by yacc.  Names affected are:  yyparse,
                         yylex, yyerror, yylval, yychar, yydebug, and yynerrs.

          -b file_prefix Use file_prefix instead of y as the prefix for output
                         filenames.  Names affected are:  y.tab.c, y.tab.h,
                         and y.output.

     If an array overflows, yacc issues a fatal error message including a
     suggestion of which table to reset.  For example:

          too many states, try -Ns option

   Debugging
     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
     is 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, the debugging code is
     included.  If its value is zero, the code is not included.  The size and
     execution time of a program produced without the runtime debugging code
     is smaller and slightly faster.

EXTERNAL INFLUENCES
   International Code Set Support
     Single-byte character code sets are supported.

ERRORS
     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.

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

WARNINGS
     Because file names are fixed, only one yacc process can be active in a
     given directory at any given time.

     The maximum number of terminal symbols is fixed at 2000 and cannot be
     reset using the -N option.

SEE ALSO
     lex(1), malloc(3X).

     YACC - Yet Another Compiler Compiler tutorial in C Programming Tools
     manual.

     Compilers - Principles, Techniques, and Tools by Aho, Sethi, and Ullman;
     Addison-Wesley ISBN 0-201-10088-6.