TiXmlHandle Class Reference

A TiXmlHandle is a class that wraps a node pointer with null checks; this is an incredibly useful thing. More...

#include <tinyxml.h>

List of all members.

Public Member Functions
	TiXmlHandle (TiXmlNode *_node)
	Create a handle from any node (at any depth of the tree.) This can be a null pointer.
	TiXmlHandle (const TiXmlHandle &ref)
	Copy constructor.
TiXmlHandle	FirstChild () const
	Return a handle to the first child node.
TiXmlHandle	FirstChild (const char *value) const
	Return a handle to the first child node with the given name.
TiXmlHandle	FirstChildElement () const
	Return a handle to the first child element.
TiXmlHandle	FirstChildElement (const char *value) const
	Return a handle to the first child element with the given name.
TiXmlHandle	Child (const char *value, int index) const
	Return a handle to the "index" child with the given name.
TiXmlHandle	Child (int index) const
	Return a handle to the "index" child.
TiXmlHandle	ChildElement (const char *value, int index) const
	Return a handle to the "index" child element with the given name.
TiXmlHandle	ChildElement (int index) const
	Return a handle to the "index" child element.
TiXmlNode *	Node () const
	Return the handle as a TiXmlNode. This may return null.
TiXmlElement *	Element () const
	Return the handle as a TiXmlElement. This may return null.
TiXmlText *	Text () const
	Return the handle as a TiXmlText. This may return null.
TiXmlUnknown *	Unknown () const
	Return the handle as a TiXmlUnknown. This may return null;.

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Detailed Description

A TiXmlHandle is a class that wraps a node pointer with null checks; this is an incredibly useful thing.

Note that TiXmlHandle is not part of the TinyXml DOM structure. It is a separate utility class.

Take an example:

	<Document>
		<Element attributeA = "valueA">
			<Child attributeB = "value1" />
			<Child attributeB = "value2" />
		</Element>
	<Document>
	

Assuming you want the value of "attributeB" in the 2nd "Child" element, it's very easy to write a *lot* of code that looks 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.
	

And that doesn't even cover "else" cases. TiXmlHandle addresses the verbosity of such code. A TiXmlHandle checks for null pointers so it is perfectly safe and correct to use:

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

Which is MUCH more concise and useful.

It is also safe to copy handles - internally they are nothing more than node pointers.

	TiXmlHandle handleCopy = handle;
	

What they should not be used for is iteration:

	int i=0; 
	while ( true )
	{
		TiXmlElement* child = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).Child( "Child", i ).Element();
		if ( !child )
			break;
		// do something
		++i;
	}
	

It seems reasonable, but it is in fact two embedded while loops. The Child method is a linear walk to find the element, so this code would iterate much more than it needs to. Instead, prefer:

	TiXmlElement* child = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).FirstChild( "Child" ).Element();

	for( child; child; child=child->NextSiblingElement() )
	{
		// do something
	}
	

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Member Function Documentation

TiXmlHandle TiXmlHandle::Child (  int  index  )  const

Return a handle to the "index" child. The first child is 0, the second 1, etc.

TiXmlHandle TiXmlHandle::Child (  const char *  value, int  index )  const

Return a handle to the "index" child with the given name. The first child is 0, the second 1, etc.

TiXmlHandle TiXmlHandle::ChildElement (  int  index  )  const

Return a handle to the "index" child element. The first child element is 0, the second 1, etc. Note that only TiXmlElements are indexed: other types are not counted.

TiXmlHandle TiXmlHandle::ChildElement (  const char *  value, int  index )  const

Return a handle to the "index" child element with the given name. The first child element is 0, the second 1, etc. Note that only TiXmlElements are indexed: other types are not counted.

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The documentation for this class was generated from the following file:

• tinyxml.h

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