YACC(1)                                                   YACC(1)

     NAME
          yacc - yet another compiler-compiler

     SYNOPSIS
          yacc [ -vd ] grammar

     DESCRIPTION
          Yacc converts a context-free grammar into a set of tables
          for a simple automaton which executes an LR(1) parsing algo-
          rithm.  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; 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.

     FILES
          y.output
          y.tab.c
          y.tab.h             defines for token names
          yacc.tmp, yacc.acts temporary files
          /usr/lib/yaccpar    parser prototype for C programs
          /lib/liby.a         library with default `main' and `yyer-
          ror'

     SEE ALSO
          lex(1)
          LR Parsing by A. V. Aho and S. C. Johnson, Computing Sur-
          veys, June, 1974.
          YACC - Yet Another Compiler Compiler by S. C. Johnson.

     DIAGNOSTICS
          The number of reduce-reduce and shift-reduce conflicts is
          reported on the standard 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.

     YACC(1)                                                   YACC(1)

     BUGS
          Because file names are fixed, at most one yacc process can
          be active in a given directory at a time.