Name

Synopsis

Description

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

Diagnostics

Table of Contents

• Name
• Synopsis
• Description
• Options
• See Also
• Diagnostics