1DTDReader(3)          User Contributed Perl Documentation         DTDReader(3)
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NAME

6       XML::Simple::DTDReader - Simple XML file reading based on their DTDs
7

SYNOPSIS

9         use XML::Simple::DTDReader;
10
11         my $ref = XMLin("data.xml");
12
13       Or the object oriented way:
14
15         require XML::Simple::DTDReader;
16
17         my $xsd = XML::Simple::DTDReader->new;
18         my $ref = $xsd->XMLin("data.xml");
19

DESCRIPTION

21       XML::Simple::DTDReader aims to be a XML::Simple drop-in replacement,
22       but with several aspects of the module controlled by the XML's DTD.
23       Specifically, array folding and array forcing are inferred from the
24       DTD.
25
26       Currently, only "XMLin" is supported; support for "XMLout" is planned
27       for later releases.
28
29   XMLin()
30       Parses XML formatted data and returns a reference to a data structure
31       which contains the same information in a more readily accessible form.
32       (Skip down to "EXAMPLES" for sample code).  The XML must have a valid
33       <!DOCTYPE> element.
34
35       "XMLin()" accepts an optional XML specifier, which can be one of the
36       following:
37
38       A filename
39           If the filename contains no directory components "XMLin()" will
40           look for the file in the current directory.  Note, the filename '-'
41           can be used to parse from STDIN.  eg:
42
43             $ref = XMLin('/etc/params.xml');
44
45       undef
46           If there is no XML specifier, "XMLin()" will check the script
47           directory for a file with the same name as the script but with the
48           extension '.xml'.  eg:
49
50             $ref = XMLin();
51
52       A string of XML
53           A string containing XML (recognized by the presence of '<' and '>'
54           characters) will be parsed directly.  eg:
55
56             $ref = XMLin('<opt username="bob" password="flurp" />');
57
58       An IO::Handle object
59           An IO::HAndle object will be read to EOF and its contents parsed.
60           eg:
61
62             $fh = new IO::File('/etc/params.xml');
63             $ref = XMLin($fh);
64

OPTIONS

66       Currently, none of XML::Simple's myriad of options are supported.
67       Support for "ContentKey", "ForceContent", "KeepRoot", "SearchPath", and
68       "ValueAttr" are planned for future releases.
69

DTD CONFIGURATION

71       XML::Simple::DTDReader is able to deal with inline and external DTDs.
72       Inline DTDs take the form:
73
74         <?xml version="1.0" encoding="UTF-8" ?>
75         <!DOCTYPE greeting [
76           <!ELEMENT greeting (#PCDATA)>
77         ]>
78         <greeting>Hello, world!</greeting>
79
80       External DTDs are either "system" DTDs or "public" DTDs.  System DTDs
81       are of the form:
82
83         <?xml version="1.0"?>
84         <!DOCTYPE greeting SYSTEM "hello.dtd">
85         <greeting>Hello, world!</greeting>
86
87       The path in the external system identifier "hello.dtd" is relative to
88       the path to the XML file in question, or to the current working
89       directory if the XML does not come from a file, or the path to the file
90       cannot be determined.
91
92       Public DTDs take the form:
93
94         <?xml version="1.0"?>
95         <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN"
96                   "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
97         <svg>
98           <path d="M202,702l1,-3l7,-3l3,1l3,7l-1,3l-7,4l-3,-1l-3,-8z" />
99         </svg>
100
101       Two properties of the DTD are used by XML::Simple::DTDReader when
102       determining the final structure of the data; repeated elements, and ID
103       attributes.  In the DTD, specifications of the form "element+" or
104       "element*" will lead to the key "element" mapping to an anonymous
105       array.  This is perhaps best illustrated with an example:
106
107         <?xml version="1.0" encoding="iso-8859-1"?>
108         <!DOCTYPE data [
109           <!ELEMENT data (stuff+)>
110           <!ELEMENT stuff (name,other*)>
111           <!ELEMENT name  (#PCDATA)>
112           <!ELEMENT other (#PCDATA)>
113         ]>
114         <data>
115           <stuff>
116             <name>Moose</name>
117             <other>Value</other>
118           </stuff>
119           <stuff>
120             <name>Thingy</name>
121             <other>Value</other>
122             <other>Value2</other>
123           </stuff>
124         </data>
125
126       ...will map to the data structure:
127
128         {
129           stuff => [
130                     {
131                      name => "Moose",
132                      other => ["Value"],
133                     },
134                     {
135                      name => "Thingy",
136                      other => ["Value", "Value2"],
137                     }
138                    ]
139         }
140
141       The other element of the DTD that impacts the data structure is ID
142       attributes.  In XML, ID attributes are unique across a file, which is a
143       more general case of Perl's restriction that keys be unique in a hash.
144       Hence, the presence of attributes of type ID will cause that layer of
145       the data to be folded into a hash, based on the value of the ID
146       attribute as the key.  This is again, best illustrated by example:
147
148         <?xml version="1.0" encoding="iso-8859-1"?>
149         <!DOCTYPE data [
150           <!ELEMENT data (stuff+)>
151           <!ELEMENT stuff (name)>
152           <!ATTLIST stuff attrib ID #REQUIRED>
153           <!ELEMENT name  (#PCDATA)>
154         ]>
155         <data>
156           <stuff attrib="first">
157             <name>Moose</name>
158           </stuff>
159           <stuff attrib="second">
160             <name>Thingy</name>
161           </stuff>
162         </data>
163
164       ...will lead to the data structure:
165
166         {
167           stuff => {
168                     first => {
169                               name => "Moose",
170                               attrib => "first"
171                              },
172                     second => {
173                                name => "Thingy",
174                                attrib => "second"
175                               }
176                    }
177         }
178
179       XML::Simple::DTDReader recognizes most ELEMENT types, with the
180       exception of mixed data (#PCDATA intermixed with elements) or ANY data.
181       Attempts to parse DTDs describing elements with these types will result
182       in an error.
183

ERROR HANDLING

185       XML::Simple::DTDReader is more strict than XML::Simple in parsing of
186       documents; not only must the documents be compliant, they must also
187       follow the DTD specified.  XML::Simple::DTDReader will die with an
188       appropriate message if it encounters a parsing of validation error.
189

EXAMPLES

191       See the "t/" directory of the distribution for a number of example XML
192       files, and the perl data structures they map to.
193

BUGS

195       None currently known, but I'm sure there are several.
196

AUTHOR

198   Contact Info
199       Alex Vandiver : alexmv@mit.edu
200
201   Copyright
202       Copyright (C) 2003 Alex Vandiver.  All rights reserved.  This package
203       is free software; you can redistribute it and/or modify it under the
204       same terms as Perl itself.
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208perl v5.28.0                      2005-07-30                      DTDReader(3)
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