Bison
is a parser generator in the style of
yacc(1).
It should be upwardly compatible with input files designed
for
yacc.
Input files should follow the
yacc
convention of ending in
.y.
Unlike
yacc,
the generated files do not have fixed names, but instead use the prefix
of the input file.
Moreover, if you need to put
C++
code in the input file, you can end his name by a C++-like extension
(.ypp or .y++), then bison will follow your extension to name the
output file (.cpp or .c++).
For instance, a grammar description file named
parse.yxx
would produce the generated parser in a file named
parse.tab.cxx,
instead of
yacc's
y.tab.c
or old
Bison
version's
parse.tab.c.
This description of the options that can be given to
bison
is adapted from the node
Invocation
in the
bison.texinfo
manual, which should be taken as authoritative.
Bison
supports both traditional single-letter options and mnemonic long
option names. Long option names are indicated with
--
instead of
-.
Abbreviations for option names are allowed as long as they
are unique. When a long option takes an argument, like
--file-prefix,
connect the option name and the argument with
=.
OPTIONS
-b file-prefix
--file-prefix=file-prefix
Specify a prefix to use for all
bison
output file names. The names are
chosen as if the input file were named
file-prefix.c.
-d
Write an extra output file containing macro definitions for the token
type names defined in the grammar and the semantic value type
YYSTYPE,
as well as a few
extern
variable declarations.
If the parser output file is named
name.c
then this file
is named
name.h.
This output file is essential if you wish to put the definition of
yylex
in a separate source file, because
yylex
needs to be able to refer to token type codes and the variable
yylval.
--defines=defines-file
The behavior of
--defines
is the same than
-d
option.
The only difference is that it has an optional argument which is
the name of the output filename.
-g
Output a VCG definition of the LALR(1) grammar automaton computed by
Bison. If the grammar file is
foo.y
, the VCG output file will be
foo.vcg.
--graph=graph-file
The behavior of
--graph
is the same than
-g
option. The only difference is that it has an optional argument which
is the name of the output graph filename.
-k
--token-table
This switch causes the
name.tab.c
output to include a list of
token names in order by their token numbers; this is defined in the array
yytname.
Also generated
are #defines for
YYNTOKENS,
YYNNTS,
YYNRULES,
and
YYNSTATES.
-l
--no-lines
Don't put any
#line
preprocessor commands in the parser file.
Ordinarily
bison
puts them in the parser file so that the C compiler
and debuggers will associate errors with your source file, the
grammar file. This option causes them to associate errors with the
parser file, treating it an independent source file in its own right.
-n
--no-parser
Do not generate the parser code into the output; generate only
declarations. The generated
name.tab.c
file will have only
constant declarations. In addition, a
name.act
file is
generated containing a switch statement body containing all the
translated actions.
-o outfile
--output-file=outfile
Specify the name
outfile
for the parser file.
The other output files' names are constructed from
outfile
as described under the
-v
and
-d
switches.
-p prefix
--name-prefix=prefix
Rename the external symbols used in the parser so that they start with
prefix
instead of
yy.
The precise list of symbols renamed is
yyparse,
yylex,
yyerror,
yylval,
yychar,
and
yydebug.
For example, if you use
-p c,
the names become
cparse,
clex,
and so on.
-t
--debug
In the parser file, define the macro
YYDEBUG
to 1 if it is not already defined,
so that the debugging facilities are compiled.
-v
--verbose
Write an extra output file containing verbose descriptions of the
parser states and what is done for each type of look-ahead token in
that state.
This file also describes all the conflicts, both those resolved by
operator precedence and the unresolved ones.
The file's name is made by removing
.tab.c
or
.c
from the parser output file name, and adding
.output
instead.
Therefore, if the input file is
foo.y,
then the parser file is called
foo.tab.c
by default. As a consequence, the verbose
output file is called
foo.output.
-V
--version
Print the version number of
bison
and exit.
-h
--help
Print a summary of the options to
bison
and exit.
-y
--yacc
--fixed-output-files
Equivalent to
-o y.tab.c;
the parser output file is called
y.tab.c,
and the other outputs are called
y.output
and
y.tab.h.
The purpose of this switch is to imitate
yacc's
output file name conventions.
Thus, the following shell script can substitute for
yacc
and is often installed as
yacc:
bison -y "$@"
SEE ALSO
yacc(1)
The
Bison Reference Manual,
included as the file
bison.texinfo
in the
bison
source distribution.
