Config::Grammar - A grammar-based, user-friendly config parser
use Config::Grammar;
my $parser = Config::Grammar->new(\%grammar); my $cfg = $parser->parse('app.cfg') or die "ERROR: $parser->{err}\n"; my $pod = $parser->makepod(); my $ex = $parser->maketmpl('TOP','SubNode');
Config::Grammar is a module to parse configuration files. The configuration may consist of multiple-level sections with assignments and tabular data. The parsed data will be returned as a hash containing the whole configuration. Config::Grammar uses a grammar that is supplied upon creation of a Config::Grammar object to parse the configuration file and return helpful error messages in case of syntax errors. Using the makepod method you can generate documentation of the configuration file format.
The maketmpl method can generate a template configuration file. If your grammar contains regexp matches, the template will not be all that helpful as Config::Grammar is not smart enough to give you sensible template data based in regular expressions.
The grammar is a multiple-level hash of hashes, which follows the structure of the configuration. Each section or variable is represented by a hash with the same structure. Each hash contains special keys starting with an underscore such as '_sections', '_vars', '_sub' or '_re' to denote meta data with information about that section or variable. Other keys are used to structure the hash according to the same nesting structure of the configuration itself. The starting hash given as parameter to 'new' contains the ``root section''.
The sub-section can also be a regular expression denoted by the syntax '/re/', where re is the regular-expression. In case a regular expression is used, a sub-hash named with the same '/re/' must be included in this hash.
The same effect can be accomplished with circular references in the grammar tree or a suitable _dyn section subroutine (see below}, so this facility is included just for convenience.
_text is a hash reference which can contain a _re and a _re_error key which will be used to scrutanize the text ... if the hash is empty, all text will be accepted.
The '_sub' function (see below) of any variables defined in this section will also receive a list of those variables already defined in the same section. This can be used to enforce the order of the variables during parsing.
_dyn()
subroutine is then called for each of
these names and the differences of the resulting grammar and
the original one are documented. This module can currently document
differences in the _vars list, listing new variables and removed
ones, and differences in the _sections list, listing the
new and removed sections.
If the '_varlist' key (see above) is defined in this section, the '_sub' function will also receive an array reference as the second argument. The array contains a list of those variables already defined in the same section. This can be used to enforce the order of the variables.
Note that no _dyn()
call is made for default and inherited values of
the variable.
_dyn()
subroutine is then called for each of
these values and the differences of the resulting grammar and
the original one are documented. This module can currently document
differences in the _vars list, listing new variables and removed
ones, and differences in the _sections list, listing the
new and removed sections.
'#' denotes a comment up to the end-of-line, empty lines are allowed and space at the beginning and end of lines is trimmed.
'\' at the end of the line marks a continued line on the next line. A single space will be inserted between the concatenated lines.
'@include filename' is used to include another file.
'@define a some value' will replace all occurences of 'a' in the following text with 'some value'.
Fields in tables that contain white space can be enclosed in either '
or "
.
Whitespace can also be escaped with \
. Quotes inside quotes are allowed but must
be escaped with a backslash as well.
Config::Grammar supports hierarchical configurations through sections, whose syntax is as follows:
Assignements take the form: 'variable = value', where value can be any string (can contain whitespaces and special characters). The spaces before and after the equal sign are optional.
The data is interpreted as one or more columns separated by spaces.
my $parser = Config::Grammar->new({ _sections => [ 'network', 'hosts' ], network => { _vars => [ 'dns' ], _sections => [ "/$RE_IP/" ], dns => { _doc => "address of the dns server", _example => "ns1.oetiker.xs", _re => $RE_HOST, _re_error => 'dns must be an host name or ip address', }, "/$RE_IP/" => { _doc => "Ip Adress", _example => '10.2.3.2', _vars => [ 'netmask', 'gateway' ], netmask => { _doc => "Netmask", _example => "255.255.255.0", _re => $RE_IP, _re_error => 'netmask must be a dotted ip address' }, gateway => { _doc => "Default Gateway address in IP notation", _example => "10.22.12.1", _re => $RE_IP, _re_error => 'gateway must be a dotted ip address' }, }, }, hosts => { _doc => "Details about the hosts", _table => { _doc => "Description of all the Hosts", _key => 0, _columns => 3, 0 => { _doc => "Ethernet Address", _example => "0:3:3:d:a:3:dd:a:cd", _re => $RE_MAC, _re_error => 'first column must be an ethernet mac address', }, 1 => { _doc => "IP Address", _example => "10.11.23.1", _re => $RE_IP, _re_error => 'second column must be a dotted ip address', }, 2 => { _doc => "Host Name", _example => "tardis", }, }, }, });
my $cfg = $parser->parse('test.cfg') or die "ERROR: $parser->{err}\n"; print Dumper($cfg); print $praser->makepod;
*** network *** dns = 192.168.7.87 + 192.168.7.64 netmask = 255.255.255.192 gateway = 192.168.7.65 *** hosts *** 00:50:fe:bc:65:11 192.168.7.97 plain.hades 00:50:fe:bc:65:12 192.168.7.98 isg.ee.hades 00:50:fe:bc:65:14 192.168.7.99 isg.ee.hades
{ 'hosts' => { '00:50:fe:bc:65:11' => [ '00:50:fe:bc:65:11', '192.168.7.97', 'plain.hades' ], '00:50:fe:bc:65:12' => [ '00:50:fe:bc:65:12', '192.168.7.98', 'isg.ee.hades' ], '00:50:fe:bc:65:14' => [ '00:50:fe:bc:65:14', '192.168.7.99', 'isg.ee.hades' ] }, 'network' => { '192.168.7.64' => { 'netmask' => '255.255.255.192', 'gateway' => '192.168.7.65' }, 'dns' => '192.168.7.87' } };
Copyright (c) 2000-2005 by ETH Zurich. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
David Schweikert <dws_at_ee.ethz.ch>, Tobias Oetiker <oetiker_at_ee.ethz.ch>, Niko Tyni <ntyni_at_iki.fi>
2001-05-11 ds Initial Version of ISG::ParseConfig 2005-03-08 ds 1.00 Renamed from ISG::ParseConfig to Config::Grammar