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325 lines
11 KiB
Markdown
325 lines
11 KiB
Markdown
TinyXML-2
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=========
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TinyXML-2 is a simple, small, efficient, C++ XML parser that can be
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easily integrated into other programs.
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The master is hosted on github:
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https://github.com/leethomason/tinyxml2
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The online HTML version of these docs:
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http://grinninglizard.com/tinyxml2docs/index.html
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Examples are in the "related pages" tab of the HTML docs.
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What it does.
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-------------
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In brief, TinyXML-2 parses an XML document, and builds from that a
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Document Object Model (DOM) that can be read, modified, and saved.
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XML stands for "eXtensible Markup Language." It is a general purpose
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human and machine readable markup language to describe arbitrary data.
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All those random file formats created to store application data can
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all be replaced with XML. One parser for everything.
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http://en.wikipedia.org/wiki/XML
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There are different ways to access and interact with XML data.
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TinyXML-2 uses a Document Object Model (DOM), meaning the XML data is parsed
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into a C++ objects that can be browsed and manipulated, and then
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written to disk or another output stream. You can also construct an XML document
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from scratch with C++ objects and write this to disk or another output
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stream. You can even use TinyXML-2 to stream XML programmatically from
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code without creating a document first.
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TinyXML-2 is designed to be easy and fast to learn. It is one header and
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one cpp file. Simply add these to your project and off you go.
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There is an example file - xmltest.cpp - to get you started.
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TinyXML-2 is released under the ZLib license,
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so you can use it in open source or commercial code. The details
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of the license are at the top of every source file.
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TinyXML-2 attempts to be a flexible parser, but with truly correct and
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compliant XML output. TinyXML-2 should compile on any reasonably C++
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compliant system. It does not rely on exceptions, RTTI, or the STL.
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What it doesn't do.
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-------------------
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TinyXML-2 doesn't parse or use DTDs (Document Type Definitions) or XSLs
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(eXtensible Stylesheet Language.) There are other parsers out there
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that are much more fully featured. But they are also much bigger,
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take longer to set up in your project, have a higher learning curve,
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and often have a more restrictive license. If you are working with
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browsers or have more complete XML needs, TinyXML-2 is not the parser for you.
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TinyXML-1 vs. TinyXML-2
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-----------------------
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TinyXML-2 is now the focus of all development, well tested, and your
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best choice unless you have a requirement to maintain TinyXML-1 code.
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TinyXML-2 uses a similar API to TinyXML-1 and the same
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rich test cases. But the implementation of the parser is completely re-written
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to make it more appropriate for use in a game. It uses less memory, is faster,
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and uses far fewer memory allocations.
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TinyXML-2 has no requirement for STL, but has also dropped all STL support. All
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strings are query and set as 'const char*'. This allows the use of internal
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allocators, and keeps the code much simpler.
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Both parsers:
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1. Simple to use with similar APIs.
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2. DOM based parser.
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3. UTF-8 Unicode support. http://en.wikipedia.org/wiki/UTF-8
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Advantages of TinyXML-2
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1. The focus of all future dev.
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2. Many fewer memory allocation (1/10th to 1/100th), uses less memory
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(about 40% of TinyXML-1), and faster.
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3. No STL requirement.
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4. More modern C++, including a proper namespace.
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5. Proper and useful handling of whitespace
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Advantages of TinyXML-1
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1. Can report the location of parsing errors.
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2. Support for some C++ STL conventions: streams and strings
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3. Very mature and well debugged code base.
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Features
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--------
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### Memory Model
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An XMLDocument is a C++ object like any other, that can be on the stack, or
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new'd and deleted on the heap.
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However, any sub-node of the Document, XMLElement, XMLText, etc, can only
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be created by calling the appropriate XMLDocument::NewElement, NewText, etc.
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method. Although you have pointers to these objects, they are still owned
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by the Document. When the Document is deleted, so are all the nodes it contains.
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### White Space
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#### Whitespace Preservation (default)
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Microsoft has an excellent article on white space: http://msdn.microsoft.com/en-us/library/ms256097.aspx
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By default, TinyXML-2 preserves white space in a (hopefully) sane way that is almost complient with the
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spec. (TinyXML-1 used a completely different model, much more similar to 'collapse', below.)
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As a first step, all newlines / carriage-returns / line-feeds are normalized to a
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line-feed character, as required by the XML spec.
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White space in text is preserved. For example:
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<element> Hello, World</element>
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The leading space before the "Hello" and the double space after the comma are
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preserved. Line-feeds are preserved, as in this example:
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<element> Hello again,
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World</element>
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However, white space between elements is **not** preserved. Although not strictly
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compliant, tracking and reporting inter-element space is awkward, and not normally
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valuable. TinyXML-2 sees these as the same XML:
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<document>
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<data>1</data>
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<data>2</data>
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<data>3</data>
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</document>
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<document><data>1</data><data>2</data><data>3</data></document>
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#### Whitespace Collapse
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For some applications, it is preferable to collapse whitespace. Collapsing
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whitespace gives you "HTML-like" behavior, which is sometimes more suitable
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for hand typed documents.
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TinyXML-2 supports this with the 'whitespace' parameter to the XMLDocument constructor.
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(The default is to preserve whitespace, as described above.)
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However, you may also use COLLAPSE_WHITESPACE, which will:
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* Remove leading and trailing whitespace
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* Convert newlines and line-feeds into a space character
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* Collapse a run of any number of space characters into a single space character
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Note that (currently) there is a performance impact for using COLLAPSE_WHITESPACE.
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It essentially causes the XML to be parsed twice.
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### Entities
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TinyXML-2 recognizes the pre-defined "character entities", meaning special
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characters. Namely:
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& &
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< <
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> >
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" "
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' '
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These are recognized when the XML document is read, and translated to their
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UTF-8 equivalents. For instance, text with the XML of:
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Far & Away
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will have the Value() of "Far & Away" when queried from the XMLText object,
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and will be written back to the XML stream/file as an ampersand.
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Additionally, any character can be specified by its Unicode code point:
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The syntax " " or " " are both to the non-breaking space characher.
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This is called a 'numeric character reference'. Any numeric character reference
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that isn't one of the special entities above, will be read, but written as a
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regular code point. The output is correct, but the entity syntax isn't preserved.
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### Printing
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#### Print to file
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You can directly use the convenience function:
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XMLDocument doc;
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...
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doc.SaveFile( "foo.xml" );
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Or the XMLPrinter class:
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XMLPrinter printer( fp );
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doc.Print( &printer );
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#### Print to memory
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Printing to memory is supported by the XMLPrinter.
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XMLPrinter printer;
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doc.Print( &printer );
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// printer.CStr() has a const char* to the XML
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#### Print without an XMLDocument
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When loading, an XML parser is very useful. However, sometimes
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when saving, it just gets in the way. The code is often set up
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for streaming, and constructing the DOM is just overhead.
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The Printer supports the streaming case. The following code
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prints out a trivially simple XML file without ever creating
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an XML document.
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XMLPrinter printer( fp );
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printer.OpenElement( "foo" );
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printer.PushAttribute( "foo", "bar" );
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printer.CloseElement();
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Examples
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--------
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#### Load and parse an XML file.
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/* ------ Example 1: Load and parse an XML file. ---- */
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{
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XMLDocument doc;
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doc.LoadFile( "dream.xml" );
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}
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#### Lookup information.
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/* ------ Example 2: Lookup information. ---- */
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{
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XMLDocument doc;
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doc.LoadFile( "dream.xml" );
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// Structure of the XML file:
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// - Element "PLAY" the root Element, which is the
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// FirstChildElement of the Document
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// - - Element "TITLE" child of the root PLAY Element
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// - - - Text child of the TITLE Element
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// Navigate to the title, using the convenience function,
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// with a dangerous lack of error checking.
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const char* title = doc.FirstChildElement( "PLAY" )->FirstChildElement( "TITLE" )->GetText();
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printf( "Name of play (1): %s\n", title );
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// Text is just another Node to TinyXML-2. The more
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// general way to get to the XMLText:
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XMLText* textNode = doc.FirstChildElement( "PLAY" )->FirstChildElement( "TITLE" )->FirstChild()->ToText();
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title = textNode->Value();
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printf( "Name of play (2): %s\n", title );
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}
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Using and Installing
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--------------------
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There are 2 files in TinyXML-2:
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* tinyxml2.cpp
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* tinyxml2.h
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And additionally a test file:
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* xmltest.cpp
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Simply compile and run. There is a visual studio 2010 project included, a simple Makefile,
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an XCode project, a Code::Blocks project, and a cmake CMakeLists.txt included to help you.
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The top of tinyxml.h even has a simple g++ command line if you are are *nix and don't want
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to use a build system.
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Versioning
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----------
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TinyXML-2 uses semantic versioning. http://semver.org/ Releases are now tagged in github.
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Note that the major version will (probably) change fairly rapidly. API changes are fairly
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common.
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Documentation
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-------------
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The documentation is build with Doxygen, using the 'dox'
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configuration file.
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License
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-------
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TinyXML-2 is released under the zlib license:
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any
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damages arising from the use of this software.
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Permission is granted to anyone to use this software for any
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purpose, including commercial applications, and to alter it and
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redistribute it freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must
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not claim that you wrote the original software. If you use this
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software in a product, an acknowledgment in the product documentation
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would be appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and
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must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source
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distribution.
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Contributors
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------------
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Thanks very much to everyone who sends suggestions, bugs, ideas, and
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encouragement. It all helps, and makes this project fun.
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The original TinyXML-1 has many contributors, who all deserve thanks
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in shaping what is a very successful library. Extra thanks to Yves
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Berquin and Andrew Ellerton who were key contributors.
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TinyXML-2 grew from that effort. Lee Thomason is the original author
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of TinyXML-2 (and TinyXML-1) but TinyXML-2 has been and is being improved
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by many contributors.
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Thanks to John Mackay at http://john.mackay.rosalilastudio.com for the TinyXML-2 logo!
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