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How To Serialize a CTreeCtrl in XML

, 3 May 2006 CPOL
Extend derived CTreeCtrl classes with an easy and fast to use approach for XML serialisation.
/** @mainpage

<h1> TinyXml </h1>

TinyXml is a simple, small, C++ XML parser that can be easily 
integrating into other programs.

<h2> What it does. </h2>
In brief, TinyXml parses an XML document, and builds from that a 
Document Object Model (DOM) that can be read, modified, and saved.

XML stands for "eXtensible Markup Language." It allows you to create 
your own document markups. Where HTML does a very good job of marking 
documents for browsers, XML allows you to define any kind of document 
markup, for example a document that describes a "to do" list for an 
organizer application. XML is a very structured and convenient format.
All those random file formats created to store application data can 
all be replaced with XML. One parser for everything.

The best place for the complete, correct, and quite frankly hard to
read spec is at <a href=""></a>. An intro to XML
(that I really like) can be found at 
<a href=""></a>.

There are different ways to access and interact with XML data.
TinyXml uses a Document Object Model (DOM), meaning the XML data is parsed
into a C++ objects that can be browsed and manipulated, and then 
written to disk or another output stream. You can also construct an XML document from
scratch with C++ objects and write this to disk or another output

TinyXml is designed to be easy and fast to learn. It is two headers 
and four cpp files. Simply add these to your project and off you go. 
There is an example file - xmltest.cpp - to get you started. 

TinyXml is released under the ZLib license, 
so you can use it in open source or commercial code. The details
of the license are at the top of every source file.

TinyXml attempts to be a flexible parser, but with truly correct and
compliant XML output. TinyXml should compile on any reasonably C++
compliant system. It does not rely on exceptions or RTTI. It can be 
compiled with or without STL support. TinyXml fully supports
the UTF-8 encoding, and the first 64k character entities.

<h2> What it doesn't do. </h2>

It doesnt parse or use DTDs (Document Type Definitions) or XSLs
(eXtensible Stylesheet Language.) There are other parsers out there 
(check out, search for XML) that are much more fully
featured. But they are also much bigger, take longer to set up in
your project, have a higher learning curve, and often have a more
restrictive license. If you are working with browsers or have more
complete XML needs, TinyXml is not the parser for you.

The following DTD syntax will not parse at this time in TinyXml:

	<!DOCTYPE Archiv [
	 <!ELEMENT Comment (#PCDATA)>

because TinyXml sees this as a !DOCTYPE node with an illegally 
embedded !ELEMENT node. This may be addressed in the future.

<h2> Tutorials. </h2>

For the impatient, here is a tutorial to get you going. A great way to get started, 
but it is worth your time to read this (very short) manual completely.

- @subpage tutorial0

<h2> Code Status.  </h2>

TinyXml is mature, tested code. It is very stable. If you find
bugs, please file a bug report on the sourceforge web site
We'll get them straightened out as soon as possible.

There are some areas of improvement; please check sourceforge if you are
interested in working on TinyXml.

<h2> Features </h2>

<h3> Using STL </h3>

TinyXml can be compiled to use or not use STL. When using STL, TinyXml
uses the std::string class, and fully supports std::istream, std::ostream,
operator<<, and operator>>. Many API methods have both 'const char*' and
'const std::string&' forms.

When STL support is compiled out, no STL files are included whatsover. All
the string classes are implemented by TinyXml itself. API methods
all use the 'const char*' form for input.

Use the compile time #define:


to compile one version or the other. This can be passed by the compiler,
or set as the first line of "tinyxml.h".

Note: If compiling the test code in Linux, setting the environment
variable TINYXML_USE_STL=YES/NO will control STL compilation. In the
Windows project file, STL and non STL targets are provided. In your project,
its probably easiest to add the line "#define TIXML_USE_STL" as the first
line of tinyxml.h.

<h3> UTF-8 </h3>

TinyXml supports UTF-8 allowing to manipulate XML files in any language. TinyXml
also supports "legacy mode" - the encoding used before UTF-8 support and
probably best described as "extended ascii".

Normally, TinyXml will try to detect the correct encoding and use it. However,
by setting the value of TIXML_DEFAULT_ENCODING in the header file, TinyXml
can be forced to always use one encoding.

TinyXml will assume Legacy Mode until one of the following occurs:
	<li> If the non-standard but common "UTF-8 lead bytes" (0xef 0xbb 0xbf)
		 begin the file or data stream, TinyXml will read it as UTF-8. </li>
	<li> If the declaration tag is read, and it has an encoding="UTF-8", then
		 TinyXml will read it as UTF-8. </li>
	<li> If the declaration tag is read, and it has no encoding specified, then
		 TinyXml will read it as UTF-8. </li>
	<li> If the declaration tag is read, and it has an encoding="something else", then
		 TinyXml will read it as Legacy Mode. In legacy mode, TinyXml will 
		 work as it did before. It's not clear what that mode does exactly, but 
		 old content should keep working.</li>
	<li> Until one of the above criteria is met, TinyXml runs in Legacy Mode.</li>

What happens if the encoding is incorrectly set or detected? TinyXml will try
to read and pass through text seen as improperly encoded. You may get some strange
results or mangled characters. You may want to force TinyXml to the correct mode.

<b> You may force TinyXml to Legacy Mode by using LoadFile( TIXML_ENCODING_LEGACY ) or
LoadFile( filename, TIXML_ENCODING_LEGACY ). You may force it to use legacy mode all
the time by setting TIXML_DEFAULT_ENCODING = TIXML_ENCODING_LEGACY. Likewise, you may 
force it to TIXML_ENCODING_UTF8 with the same technique.</b>

For English users, using English XML, UTF-8 is the same as low-ASCII. You
don't need to be aware of UTF-8 or change your code in any way. You can think
of UTF-8 as a "superset" of ASCII.

UTF-8 is not a double byte format - but it is a standard encoding of Unicode!
TinyXml does not use or directly support wchar, TCHAR, or Microsofts _UNICODE at this time. 
It is common to see the term "Unicode" improperly refer to UTF-16, a wide byte encoding
of unicode. This is a source of confusion.

For "high-ascii" languages - everything not English, pretty much - TinyXml can
handle all languages, at the same time, as long as the XML is encoded
in UTF-8. That can be a little tricky, older programs and operating systems
tend to use the "default" or "traditional" code page. Many apps (and almost all
modern ones) can output UTF-8, but older or stubborn (or just broken) ones
still output text in the default code page. 

For example, Japanese systems traditionally use SHIFT-JIS encoding. 
Text encoded as SHIFT-JIS can not be read by tinyxml. 
A good text editor can import SHIFT-JIS and then save as UTF-8.

The <a href=""> link</a> does a great
job covering the encoding issue.

The test file "utf8test.xml" is an XML containing English, Spanish, Russian,
and Simplified Chinese. (Hopefully they are translated correctly). The file
"utf8test.gif" is a screen capture of the XML file, rendered in IE. Note that
if you don't have the correct fonts (Simplified Chinese or Russian) on your
system, you won't see output that matches the GIF file even if you can parse
it correctly. Also note that (at least on my Windows machine) console output
is in a Western code page, so that Print() or printf() cannot correctly display
the file. This is not a bug in TinyXml - just an OS issue. No data is lost or 
destroyed by TinyXml. The console just doesn't render UTF-8.

<h3> Entities </h3>
TinyXml recognizes the pre-defined "character entities", meaning special
characters. Namely:

	&amp;	&
	&lt;	<
	&gt;	>
	&quot;	"
	&apos;	'

These are recognized when the XML document is read, and translated to there
UTF-8 equivalents. For instance, text with the XML of:

	Far &amp; Away

will have the Value() of "Far & Away" when queried from the TiXmlText object,
and will be written back to the XML stream/file as an ampersand. Older versions
of TinyXml "preserved" character entities, but the newer versions will translate
them into characters.

Additionally, any character can be specified by its Unicode code point:
The syntax "&#xA0;" or "&#160;" are both to the non-breaking space characher.

<h3> Streams </h3>
TiXml has been modified to support both C (FILE) and C++ (operator <<,>>) 
streams. There are some differences that you may need to be aware of.

C style output:
	- based on FILE*
	- the Print() and SaveFile() methods

	Generates formatted output, with plenty of white space, intended to be as 
	human-readable as possible. They are very fast, and tolerant of ill formed 
	XML documents. For example, an XML document that contains 2 root elements 
	and 2 declarations, will still print.

C style input:
	- based on FILE*
	- the Parse() and LoadFile() methods

	A fast, tolerant read. Use whenever you don't need the C++ streams.

C++ style ouput:
	- based on std::ostream
	- operator<<

	Generates condensed output, intended for network transmission rather than
	readability. Depending on your system's implementation of the ostream class,
	these may be somewhat slower. (Or may not.) Not tolerant of ill formed XML:
	a document should contain the correct one root element. Additional root level
	elements will not be streamed out.

C++ style input:
	- based on std::istream
	- operator>>

	Reads XML from a stream, making it useful for network transmission. The tricky
	part is knowing when the XML document is complete, since there will almost
	certainly be other data in the stream. TinyXml will assume the XML data is
	complete after it reads the root element. Put another way, documents that
	are ill-constructed with more than one root element will not read correctly.
	Also note that operator>> is somewhat slower than Parse, due to both 
	implementation of the STL and limitations of TinyXml.

<h3> White space </h3>
The world simply does not agree on whether white space should be kept, or condensed.
For example, pretend the '_' is a space, and look at "Hello____world". HTML, and 
at least some XML parsers, will interpret this as "Hello_world". They condense white
space. Some XML parsers do not, and will leave it as "Hello____world". (Remember
to keep pretending the _ is a space.) Others suggest that __Hello___world__ should become

It's an issue that hasn't been resolved to my satisfaction. TinyXml supports the
first 2 approaches. Call TiXmlBase::SetCondenseWhiteSpace( bool ) to set the desired behavior.
The default is to condense white space.

If you change the default, you should call TiXmlBase::SetCondenseWhiteSpace( bool )
before making any calls to Parse XML data, and I don't recommend changing it after
it has been set.

<h3> Handles </h3>

Where browsing an XML document in a robust way, it is important to check
for null returns from method calls. An error safe implementation can
generate a lot of code like:

TiXmlElement* root = document.FirstChildElement( "Document" );
if ( root )
	TiXmlElement* element = root->FirstChildElement( "Element" );
	if ( element )
		TiXmlElement* child = element->FirstChildElement( "Child" );
		if ( child )
			TiXmlElement* child2 = child->NextSiblingElement( "Child" );
			if ( child2 )
				// Finally do something useful.

Handles have been introduced to clean this up. Using the TiXmlHandle class,
the previous code reduces to:

TiXmlHandle docHandle( &document );
TiXmlElement* child2 = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).Child( "Child", 1 ).Element();
if ( child2 )
	// do something useful

Which is much easier to deal with. See TiXmlHandle for more information.

<h3> Row and Column tracking </h3>
Being able to track nodes and attributes back to their origin location
in source files can be very important for some applications. Additionally,
knowing where parsing errors occured in the original source can be very
time saving.

TinyXml can tracks the row and column origin of all nodes and attributes
in a text file. The TiXmlBase::Row() and TiXmlBase::Column() methods return
the origin of the node in the source text. The correct tabs can be 
configured in TiXmlDocument::SetTabSize().

<h2> Using and Installing </h2>

To Compile and Run xmltest:

A Linux Makefile and a Windows Visual C++ .dsw file is provided. 
Simply compile and run. It will write the file demotest.xml to your 
disk and generate output on the screen. It also tests walking the
DOM by printing out the number of nodes found using different 

The Linux makefile is very generic and will
probably run on other systems, but is only tested on Linux. You no
longer need to run 'make depend'. The dependecies have been
hard coded.

<h3>Windows project file for VC6</h3>
<li>tinyxml:		tinyxml library, non-STL </li>
<li>tinyxmlSTL:		tinyxml library, STL </li>
<li>tinyXmlTest:	test app, non-STL </li>
<li>tinyXmlTestSTL: test app, STL </li>

<h3>Linux Make file</h3>
At the top of the makefile you can set:

PROFILE, DEBUG, and TINYXML_USE_STL. Details (such that they are) are in
the makefile.

In the tinyxml directory, type "make clean" then "make". The executable
file 'xmltest' will be created.

<h3>To Use in an Application:</h3>

Add tinyxml.cpp, tinyxml.h, tinyxmlerror.cpp, tinyxmlparser.cpp, tinystr.cpp, and tinystr.h to your
project or make file. That's it! It should compile on any reasonably
compliant C++ system. You do not need to enable exceptions or
RTTI for TinyXml.

<h2> How TinyXml works.  </h2>

An example is probably the best way to go. Take:
	<?xml version="1.0" standalone=no>
	<!-- Our to do list data -->
		<Item priority="1"> Go to the <bold>Toy store!</bold></Item>
		<Item priority="2"> Do bills</Item>

Its not much of a To Do list, but it will do. To read this file 
(say "demo.xml") you would create a document, and parse it in:
	TiXmlDocument doc( "demo.xml" );

And its ready to go. Now lets look at some lines and how they 
relate to the DOM.

<?xml version="1.0" standalone=no>

	The first line is a declaration, and gets turned into the
	TiXmlDeclaration class. It will be the first child of the
	document node.
	This is the only directive/special tag parsed by by TinyXml.
	Generally directive targs are stored in TiXmlUnknown so the 
	commands wont be lost when it is saved back to disk.

<!-- Our to do list data -->

	A comment. Will become a TiXmlComment object.


	The "ToDo" tag defines a TiXmlElement object. This one does not have 
	any attributes, but does contain 2 other elements.

<Item priority="1"> 

	Creates another TiXmlElement which is a child of the "ToDo" element. 
	This element has 1 attribute, with the name "priority" and the value 

Go to the 

	A TiXmlText. This is a leaf node and cannot contain other nodes. 
	It is a child of the "Item" TiXmlElement.


	Another TiXmlElement, this one a child of the "Item" element.


Looking at the entire object tree, you end up with:
TiXmlDocument				"demo.xml"
	TiXmlDeclaration		"version='1.0'" "standalone=no"
	TiXmlComment			" Our to do list data"
	TiXmlElement			"ToDo"
		TiXmlElement		"Item"		Attribtutes: priority = 1
			TiXmlText		"Go to the "
			TiXmlElement    "bold"
				TiXmlText	"Toy store!"
		TiXmlElement			"Item"		Attributes: priority=2
			TiXmlText			"Do bills"

<h2> Documentation </h2>

The documentation is build with Doxygen, using the 'dox' 
configuration file.

<h2> License </h2>

TinyXml is released under the zlib license:

This software is provided 'as-is', without any express or implied 
warranty. In no event will the authors be held liable for any 
damages arising from the use of this software.

Permission is granted to anyone to use this software for any 
purpose, including commercial applications, and to alter it and 
redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must 
not claim that you wrote the original software. If you use this 
software in a product, an acknowledgment in the product documentation 
would be appreciated but is not required.

2. Altered source versions must be plainly marked as such, and 
must not be misrepresented as being the original software.

3. This notice may not be removed or altered from any source 

<h2> References  </h2>

The World Wide Web Consortium is the definitive standard body for 
XML, and there web pages contain huge amounts of information. 

The definitive spec: <a href=""></a>

I also recommend "XML Pocket Reference" by Robert Eckstein and published by 
OReilly...the book that got the whole thing started.

<h2> Contributors, Contacts, and a Brief History </h2>

Thanks very much to everyone who sends suggestions, bugs, ideas, and 
encouragement. It all helps, and makes this project fun. A special thanks
to the contributors on the web pages that keep it lively.

So many people have sent in bugs and ideas, that rather than list here 
we try to give credit due in the "changes.txt" file.

TinyXml was originally written be Lee Thomason. (Often the "I" still
in the documenation.) Lee reviews changes and releases new versions,
with the help of Yves Berquin and the tinyXml community.

We appreciate your suggestions, and would love to know if you 
use TinyXml. Hopefully you will enjoy it and find it useful. 
Please post questions, comments, file bugs, or contact us at:

Lee Thomason,
Yves Berquin

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About the Author

Andreas Loeffler
Web Developer
Germany Germany
I was born in 1982 near Stuttgart / Germany and began my first steps in programming computers at the age of only nine years on an old Commodore CBM 7072. In 2002 I finished my education as IT specialist for software engineering and did my civillian service afterwards. Currently I'm working as leader of the software division in a bigger company located in south west Germany, mainly on software development and research projects for multimedia terminals and user recognition/verification systems.

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