1Config::Grammar(3) User Contributed Perl Documentation Config::Grammar(3)
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6 Config::Grammar - A grammar-based, user-friendly config parser
7
9 use Config::Grammar;
10 my $args = { encoding => 'utf8' }; # the second parameter to parse() is optional
12 my $parser = Config::Grammar->new(\%grammar);
13 my $cfg = $parser->parse('app.cfg', $args) or die "ERROR: $parser->{err}\n";
14 my $pod = $parser->makepod();
15 my $ex = $parser->maketmpl('TOP','SubNode');
16 my $minex = $parser->maketmplmin('TOP','SubNode');
17
19 Config::Grammar is a module to parse configuration files. The optional
20 second parameter to the parse() method can be used to specify the file
21 encoding to use for opening the file (see documentation for Perl's use
22 open pragma).
23 The configuration may consist of multiple-level sections with
25 assignments and tabular data. The parsed data will be returned as a
26 hash containing the whole configuration. Config::Grammar uses a grammar
27 that is supplied upon creation of a Config::Grammar object to parse the
28 configuration file and return helpful error messages in case of syntax
29 errors. Using the makepod method you can generate documentation of the
30 configuration file format.
31 The maketmpl method can generate a template configuration file. If
33 your grammar contains regexp matches, the template will not be all that
34 helpful as Config::Grammar is not smart enough to give you sensible
35 template data based in regular expressions. The related function
36 maketmplmin generates a minimal configuration template without
37 examples, regexps or comments and thus allows an experienced user to
38 fill in the configuration data more efficiently.
39 Grammar Definition
41 The grammar is a multiple-level hash of hashes, which follows the
42 structure of the configuration. Each section or variable is represented
43 by a hash with the same structure. Each hash contains special keys
44 starting with an underscore such as '_sections', '_vars', '_sub' or
45 '_re' to denote meta data with information about that section or
46 variable. Other keys are used to structure the hash according to the
47 same nesting structure of the configuration itself. The starting hash
48 given as parameter to 'new' contains the "root section".
49 Special Section Keys
51 _sections Array containing the list of sub-sections of this section.
53 Each sub-section must then be represented by a sub-hash in
54 this hash with the same name of the sub-section.
55 The sub-section can also be a regular expression denoted by
57 the syntax '/re/', where re is the regular-expression. In
58 case a regular expression is used, a sub-hash named with
59 the same '/re/' must be included in this hash.
60 _vars Array containing the list of variables (assignments) in
62 this section. Analogous to sections, regular expressions
63 can be used.
64 _mandatory Array containing the list of mandatory sections and
66 variables.
67 _inherited Array containing the list of the variables that should be
69 assigned the same value as in the parent section if nothing
70 is specified here.
71 _table Hash containing the table grammar (see Special Table Keys).
73 If not specified, no table is allowed in this section. The
74 grammar of the columns if specified by sub-hashes named
75 with the column number.
76 _text Section contains free-form text. Only sections and
78 @includes statements will be interpreted, the rest will be
79 added in the returned hash under '_text' as string.
80 _text is a hash reference which can contain a _re and a
82 _re_error key which will be used to scrutanize the text ...
83 if the hash is empty, all text will be accepted.
84 _order If defined, a '_order' element will be put in every hash
86 containing the sections with a number that determines the
87 order in which the sections were defined.
88 _doc Describes what this section is about
90 _sub A function pointer. It is called for every instance of this
92 section, with the real name of the section passed as its
93 first argument. This is probably only useful for the regexp
94 sections. If the function returns a defined value it is
95 assumed that the test was not successful and an error is
96 generated with the returned string as content.
97 Special Variable Keys
99 _re Regular expression upon which the value will be checked.
101 _re_error String containing the returned error in case the regular
103 expression doesn't match (if not specified, a generic
104 'syntax error' message will be returned).
105 _sub A function pointer. It called for every value, with the
107 value passed as its first argument. If the function returns
108 a defined value it is assumed that the test was not
109 successful and an error is generated with the returned
110 string as content.
111 If the '_varlist' key (see above) is defined in this
113 section, the '_sub' function will also receive an array
114 reference as the second argument. The array contains a list
115 of those variables already defined in the same section.
116 This can be used to enforce the order of the variables.
117 _default A default value that will be assigned to the variable if
119 none is specified or inherited.
120 _doc Description of the variable.
122 _example A one line example for the content of this variable.
124 Special Table Keys
126 _columns Number of columns. If not specified, it will not be
128 enforced.
129 _key If defined, the specified column number will be used as key
131 in a hash in the returned hash. If not defined, the
132 returned hash will contain a '_table' element with the
133 contents of the table as array. The rows of the tables are
134 stored as arrays.
135 _sub they work analog to the description in the previous
137 section.
138 _doc describes the content of the column.
140 _example example for the content of this column
142 Special Text Keys
144 _re Regular expression upon which the text will be checked
146 (everything as a single line).
147 _re_error String containing the returned error in case the regular
149 expression doesn't match (if not specified, a generic
150 'syntax error' message will be returned).
151 _sub they work analog to the description in the previous
153 section.
154 _doc Ditto.
156 _example Potential multi line example for the content of this text
158 section
159 Configuration Syntax
161 General Syntax
162 '#' denotes a comment up to the end-of-line, empty lines are allowed
164 and space at the beginning and end of lines is trimmed.
165 '\' at the end of the line marks a continued line on the next line. A
167 single space will be inserted between the concatenated lines.
168 '@include filename' is used to include another file. Include works
170 relative to the directory where the parent file is in.
171 '@define a some value' will replace all occurrences of 'a' in the
173 following text with 'some value'.
174 Fields in tables that contain white space can be enclosed in either "'"
176 or """. Whitespace can also be escaped with "\". Quotes inside quotes
177 are allowed but must be escaped with a backslash as well.
178 Sections
180 Config::Grammar supports hierarchical configurations through sections,
182 whose syntax is as follows:
183 Level 1 *** section name ***
185 Level 2 + section name
187 Level 3 ++ section name
189 Level n, n>1 +..+ section name (number of '+' determines level)
191 Assignments
193 Assignments take the form: 'variable = value', where value can be any
195 string (can contain whitespaces and special characters). The spaces
196 before and after the equal sign are optional.
197 Tabular Data
199 The data is interpreted as one or more columns separated by spaces.
201 Example
203 Code
204 use Data::Dumper;
206 use Config::Grammar;
207 my $RE_IP = '\d+\.\d+\.\d+\.\d+';
209 my $RE_MAC = '[0-9a-f]{2}(?::[0-9a-f]{2}){5}';
210 my $RE_HOST = '\S+';
211 my $parser = Config::Grammar->new({
213 _sections => [ 'network', 'hosts' ],
214 network => {
215 _vars => [ 'dns' ],
216 _sections => [ "/$RE_IP/" ],
217 dns => {
218 _doc => "address of the dns server",
219 _example => "ns1.oetiker.xs",
220 _re => $RE_HOST,
221 _re_error =>
222 'dns must be an host name or ip address',
223 },
224 "/$RE_IP/" => {
225 _doc => "Ip Adress",
226 _example => '10.2.3.2',
227 _vars => [ 'netmask', 'gateway' ],
228 netmask => {
229 _doc => "Netmask",
230 _example => "255.255.255.0",
231 _re => $RE_IP,
232 _re_error =>
233 'netmask must be a dotted ip address'
234 },
235 gateway => {
236 _doc => "Default Gateway address in IP notation",
237 _example => "10.22.12.1",
238 _re => $RE_IP,
239 _re_error =>
240 'gateway must be a dotted ip address' },
241 },
242 },
243 hosts => {
244 _doc => "Details about the hosts",
245 _table => {
246 _doc => "Description of all the Hosts",
247 _key => 0,
248 _columns => 3,
249 0 => {
250 _doc => "Ethernet Address",
251 _example => "0:3:3:d:a:3:dd:a:cd",
252 _re => $RE_MAC,
253 _re_error =>
254 'first column must be an ethernet mac address',
255 },
256 1 => {
257 _doc => "IP Address",
258 _example => "10.11.23.1",
259 _re => $RE_IP,
260 _re_error =>
261 'second column must be a dotted ip address',
262 },
263 2 => {
264 _doc => "Host Name",
265 _example => "tardis",
266 },
267 },
268 },
269 });
270 my $args = { encoding => 'utf8' }; # the second parameter to parse() is optional
272 my $cfg = $parser->parse('test.cfg', $args) or
273 die "ERROR: $parser->{err}\n";
274 print Dumper($cfg);
275 print $parser->makepod;
276 Configuration
278 *** network ***
280 dns = 192.168.7.87
282 + 192.168.7.64
284 netmask = 255.255.255.192
286 gateway = 192.168.7.65
287 *** hosts ***
289 00:50:fe:bc:65:11 192.168.7.97 plain.hades
291 00:50:fe:bc:65:12 192.168.7.98 isg.ee.hades
292 00:50:fe:bc:65:14 192.168.7.99 isg.ee.hades
293 Result
295 {
297 'hosts' => {
298 '00:50:fe:bc:65:11' => [
299 '00:50:fe:bc:65:11',
300 '192.168.7.97',
301 'plain.hades'
302 ],
303 '00:50:fe:bc:65:12' => [
304 '00:50:fe:bc:65:12',
305 '192.168.7.98',
306 'isg.ee.hades'
307 ],
308 '00:50:fe:bc:65:14' => [
309 '00:50:fe:bc:65:14',
310 '192.168.7.99',
311 'isg.ee.hades'
312 ]
313 },
314 'network' => {
315 '192.168.7.64' => {
316 'netmask' => '255.255.255.192',
317 'gateway' => '192.168.7.65'
318 },
319 'dns' => '192.168.7.87'
320 }
321 };
322
324 Config::Grammar::Dynamic
325
327 Copyright (c) 2000-2005 by ETH Zurich. All rights reserved. Copyright
328 (c) 2007 by David Schweikert. All rights reserved.
329
331 This program is free software; you can redistribute it and/or modify it
332 under the same terms as Perl itself.
333
335 David Schweikert, Tobias Oetiker, Niko Tyni
336perl v5.34.0 2022-01-21 Config::Grammar(3)