YACC(1-SysV)        RISC/os Reference Manual         YACC(1-SysV)



NAME
     yacc - yet another compiler-compiler

SYNOPSIS
     yacc [ -vdlt ] grammar

DESCRIPTION
     The yacc command converts a context-free grammar into a set
     of tables for a simple automaton which executes a parsing
     algorithm.  The grammar may be ambiguous; specified pre-
     cedence 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 lexi-
     cal 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
     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.

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



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YACC(1-SysV)        RISC/os Reference Manual         YACC(1-SysV)



     /usr/lib/yaccpar    parser prototype for C programs

SEE ALSO
     lex(1).
     Programmer's Guide.

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.

CAVEAT
     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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