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YACC(1) 			   BSD General Commands Manual				  YACC(1)

NAME
     yacc -- an LALR(1) parser generator

SYNOPSIS
     yacc [-dgilPrtVv] [-b prefix] [-o outputfile] [-p symbol_prefix] filename

DESCRIPTION
     yacc reads the grammar specification in the file filename and generates an LALR(1) parser
     for it.  The parsers consist of a set of LALR(1) parsing tables and a driver routine written
     in the C programming language.  yacc normally writes the parse tables and the driver routine
     to the file y.tab.c.

     The following options are available:

     -b prefix	   The -b option changes the prefix prepended to the output file names to the
		   string denoted by prefix.  The default prefix is the character y.

     -d 	   The -d option causes the header file y.tab.h to be written.	It contains
		   #define's for the token identifiers.

     -g 	   The -g option causes a graphical description of the generated LALR(1) parser
		   to be written to the file y.dot in graphviz format, ready to be processed by
		   dot(1).

     -i 	   The -i option causes a supplementary header file y.tab.i to be written.  It
		   contains extern declarations and supplementary #define's as needed to map the
		   conventional yacc yy-prefixed names to whatever the -p option may specify.
		   The code file, e.g., y.tab.c is modified to #include this file as well as the
		   y.tab.h file, enforcing consistent usage of the symbols defined in those
		   files.  The supplementary header file makes it simpler to separate compilation
		   of lex- and yacc-files.

     -l 	   If the -l option is not specified, yacc will insert #line directives in the
		   generated code.  The #line directives let the C compiler relate errors in the
		   generated code to the user's original code.	If the -l option is specified,
		   yacc will not insert the #line directives.  #line directives specified by the
		   user will be retained.

     -o outputfile
		   The -o option specifies an explicit output file name should be used instead of
		   the default.

     -P 	   The -P options instructs yacc to create a reentrant parser, like
		   ``%pure-parser'' does.

     -p symbol_prefix
		   The -p option changes the prefix prepended to yacc-generated symbols to the
		   string denoted by symbol_prefix.  The default prefix is the string yy.

     -r 	   The -r option causes yacc to produce separate files for code and tables.  The
		   code file is named y.code.c, and the tables file is named y.tab.c.

     -t 	   The -t option changes the preprocessor directives generated by yacc so that
		   debugging statements will be incorporated in the compiled code.

     -V 	   The -V option prints the version number to the standard output.

     -v 	   The -v option causes a human-readable description of the generated parser to
		   be written to the file y.output.

EXTENSIONS
     yacc provides some extensions for compatibility with bison(1) and other implementations of
     yacc:

     %expect number	Tell yacc the expected number of shift/reduce conflicts.  That makes it
			only report the number if it differs.
     %expect-rr number	Tell yacc the expected number of reduce/reduce conflicts.  That makes it
			only report the number if it differs.  This is (unlike bison(1)) allow-
			able in LALR(1) parsers.
     %lex-param { argument-declaration }
			By default, the lexer accepts no parameters, e.g., yylex().  Use this
			directive to add parameter declarations for your customized lexer.
     %parse-param { argument-declaration }
			By default, the parser accepts no parameters, e.g., yyparse().	Use this
			directive to add parameter declarations for your customized parser.
     %pure-parser	Most variables (other than yydebug and yynerrs) are allocated on the
			stack within yyparse(), making the parser reasonably reentrant.

ENVIRONMENT
     The following environment variable is referenced by yacc:

     TMPDIR  If the environment variable TMPDIR is set, the string denoted by TMPDIR will be used
	     as the name of the directory where the temporary files are created.

TABLES
     The names of the tables generated by this version of yacc are ``yylhs'', ``yylen'',
     ``yydefred'', ``yydgoto'', ``yysindex'', ``yyrindex'', ``yygindex'', ``yytable'', and
     ``yycheck''.  Two additional tables, ``yyname'' and ``yyrule'', are created if YYDEBUG is
     defined and non-zero.

FILES
     y.code.c
     y.tab.c
     y.tab.h
     y.output
     /tmp/yacc.aXXXXXX
     /tmp/yacc.tXXXXXX
     /tmp/yacc.uXXXXXX

DIAGNOSTICS
     If there are rules that are never reduced, the number of such rules is written to the stan-
     dard error.  If there are any LALR(1) conflicts, the number of conflicts is also written to
     the standard error.

STANDARDS
     The yacc utility conforms to IEEE Std 1003.2 (``POSIX.2'').

BSD					September 7, 2011				      BSD
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