* src/files.c (guard_obstack): New.

[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
] [
.B \-\-defines
] [
.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 \-r
] [
.B \-\-raw
] [
.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
.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.
For instance, a grammar description file named
.B parse.y
would produce the generated parser in a file named
.BR parse.tab.c ,
instead of
.IR yacc 's
.BR y.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\fB.c\fR.
.TP
.B \-d
.br
.ns
.TP
.B \-\-defines
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
\fIname\fB.c\fR
then this file
is named
\fIname\fB.h\fR.
.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
.B \-r
.br
.ns
.TP
.B \-\-raw
The token numbers in the \fIname\fB.h\fR file are usually the Yacc compatible 
translations.  If this switch is specified, Bison token numbers
are output instead.  (Yacc numbers start at 257 except for single character 
tokens;  Bison assigns token numbers sequentially for all tokens 
starting at 3.)
.TP
.B \-k
.br
.ns
.TP
.B \-\-token-table
This switch causes the \fIname\fB.tab.c\fR 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 \fIname\fB.tab.c\fR file will have only 
constant declarations.  In addition, a \fIname\fB.act\fR 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
Output a definition of the macro
.B YYDEBUG 
into the parser file,
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 look-ahead 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
.IR yacc :
.sp
.RS
.ft B
bison \-y $*
.ft R
.sp
.RE
.SH FILES
/usr/local/lib/bison.simple	simple parser
.br
/usr/local/lib/bison.hairy	complicated parser
.SH "ENVIRONMENT VARIABLES"
.TP
.SM BISON_SIMPLE
If this is set, it specifies the location in which the
.B bison.simple
parser can be found.
.TP
.SM BISON_HAIRY
If this is set, it specifies the location in which the
.B bison.hairy
parser can be found.
.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.