For consistency, use `lookahead' instead of `look-ahead' or

[bison.git] / doc / bison.1

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