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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>

Collaboration diagram for TiXmlHandle:

Collaboration graph
[legend]
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 operator= (const TiXmlHandle &ref)
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.

TiXmlHandle FirstChild (const std::string &_value) const
TiXmlHandle FirstChildElement (const std::string &_value) const
TiXmlHandle Child (const std::string &_value, int index) const
TiXmlHandle ChildElement (const std::string &_value, int index) const
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;.


Private Attributes

TiXmlNode * node

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
	}

Constructor & Destructor Documentation

TiXmlHandle::TiXmlHandle (  TiXmlNode *  _node  )  [inline]
 

Create a handle from any node (at any depth of the tree.) This can be a null pointer.

TiXmlHandle::TiXmlHandle (  const TiXmlHandle &  ref  )  [inline]
 

Copy constructor.

Member Function Documentation

TiXmlHandle TiXmlHandle::Child (  const std::string &  _value,
int  index
)  const [inline]
 

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 (  const std::string &  _value,
int  index
)  const [inline]
 

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.

TiXmlElement* TiXmlHandle::Element (   )  const [inline]
 

Return the handle as a TiXmlElement. This may return null.

TiXmlHandle TiXmlHandle::FirstChild (  const std::string &  _value  )  const [inline]
 

TiXmlHandle TiXmlHandle::FirstChild (  const char *  value  )  const
 

Return a handle to the first child node with the given name.

TiXmlHandle TiXmlHandle::FirstChild (   )  const
 

Return a handle to the first child node.

TiXmlHandle TiXmlHandle::FirstChildElement (  const std::string &  _value  )  const [inline]
 

TiXmlHandle TiXmlHandle::FirstChildElement (  const char *  value  )  const
 

Return a handle to the first child element with the given name.

TiXmlHandle TiXmlHandle::FirstChildElement (   )  const
 

Return a handle to the first child element.

TiXmlNode* TiXmlHandle::Node (   )  const [inline]
 

Return the handle as a TiXmlNode. This may return null.

TiXmlHandle TiXmlHandle::operator= (  const TiXmlHandle &  ref  )  [inline]
 

TiXmlText* TiXmlHandle::Text (   )  const [inline]
 

Return the handle as a TiXmlText. This may return null.

TiXmlUnknown* TiXmlHandle::Unknown (   )  const [inline]
 

Return the handle as a TiXmlUnknown. This may return null;.

Member Data Documentation

TiXmlNode* TiXmlHandle::node [private]
 

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