Provided by: libconfig-grammar-perl_1.10-1_all 
NAME
Config::Grammar - A grammar-based, user-friendly config parser
SYNOPSIS
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');
my $minex = $parser->maketmplmin('TOP','SubNode');
DESCRIPTION
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 related
function maketmplmin generates a minimal configuration template without examples, regexps
or comments and thus allows an experienced user to fill in the configuration data more
efficiently.
Grammar Definition
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".
Special Section Keys
_sections Array containing the list of sub-sections of this section. Each sub-section
must then be represented by a sub-hash in this hash with the same name of the
sub-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.
_vars Array containing the list of variables (assignments) in this section.
Analogous to sections, regular expressions can be used.
_mandatory Array containing the list of mandatory sections and variables.
_inherited Array containing the list of the variables that should be assigned the same
value as in the parent section if nothing is specified here.
_table Hash containing the table grammar (see Special Table Keys). If not specified,
no table is allowed in this section. The grammar of the columns if specified
by sub-hashes named with the column number.
_text Section contains free-form text. Only sections and @includes statements will
be interpreted, the rest will be added in the returned hash under '_text' as
string.
_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.
_order If defined, a '_order' element will be put in every hash containing the
sections with a number that determines the order in which the sections were
defined.
_doc Describes what this section is about
_sub A function pointer. It is called for every instance of this section, with the
real name of the section passed as its first argument. This is probably only
useful for the regexp sections. If the function returns a defined value it is
assumed that the test was not successful and an error is generated with the
returned string as content.
Special Variable Keys
_re Regular expression upon which the value will be checked.
_re_error String containing the returned error in case the regular expression doesn't
match (if not specified, a generic 'syntax error' message will be returned).
_sub A function pointer. It called for every value, with the value passed as its
first argument. If the function returns a defined value it is assumed that the
test was not successful and an error is generated with the returned string as
content.
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.
_default A default value that will be assigned to the variable if none is specified or
inherited.
_doc Description of the variable.
_example A one line example for the content of this variable.
Special Table Keys
_columns Number of columns. If not specified, it will not be enforced.
_key If defined, the specified column number will be used as key in a hash in the
returned hash. If not defined, the returned hash will contain a '_table'
element with the contents of the table as array. The rows of the tables are
stored as arrays.
_sub they work analog to the description in the previous section.
_doc describes the content of the column.
_example example for the content of this column
Special Text Keys
_re Regular expression upon which the text will be checked (everything as a single
line).
_re_error String containing the returned error in case the regular expression doesn't
match (if not specified, a generic 'syntax error' message will be returned).
_sub they work analog to the description in the previous section.
_doc Ditto.
_example Potential multi line example for the content of this text section
Configuration Syntax
General Syntax
'#' 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. Include works relative to the
directory where the parent file is in.
'@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.
Sections
Config::Grammar supports hierarchical configurations through sections, whose syntax is as
follows:
Level 1 *** section name ***
Level 2 + section name
Level 3 ++ section name
Level n, n>1 +..+ section name (number of '+' determines level)
Assignments
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.
Tabular Data
The data is interpreted as one or more columns separated by spaces.
Example
Code
use Data::Dumper;
use Config::Grammar;
my $RE_IP = '\d+\.\d+\.\d+\.\d+';
my $RE_MAC = '[0-9a-f]{2}(?::[0-9a-f]{2}){5}';
my $RE_HOST = '\S+';
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 $parser->makepod;
Configuration
*** 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
Result
{
'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'
}
};
SEE ALSO
Config::Grammar::Dynamic
COPYRIGHT
Copyright (c) 2000-2005 by ETH Zurich. All rights reserved. Copyright (c) 2007 by David
Schweikert. All rights reserved.
LICENSE
This program is free software; you can redistribute it and/or modify it under the same
terms as Perl itself.
AUTHORS
David Schweikert, Tobias Oetiker, Niko Tyni