NAME
Yacc - an LALR(1) parser generator
SYNOPSIS
yacc [ -dglrtv ] [ -b file_prefix ] [ -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 file_prefix
The -b option changes the prefix prepended to the output file
names to the string denoted by file_prefix. The default prefix
is the character y.
-d The -d option causes the header file y.tab.h to be written.
-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).
-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 output_file
specify the filename for the parser file. If this option is not
given, the output filename is the file prefix concatenated with
the file suffix, e.g., y.tab.c. This overrides the -p option.
-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.
-P create a reentrant parser, e.g., "%pure-parser".
-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 causes a human-readable description of the
generated parser to be written to the file y.output.
-V print the version number to the standard output.
EXTENSIONS
yacc provides some extensions for compatibility with bison 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) allowable in LALR 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.
DIAGNOSTICS
If there are rules that are never reduced, the number of such rules is
reported on standard error. If there are any LALR(1) conflicts, the
number of conflicts is reported on standard error.