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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>

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.

TiXmlNodeNode () const
 Return the handle as a TiXmlNode. This may return null.

TiXmlElementElement () const
 Return the handle as a TiXmlElement. This may return null.

TiXmlTextText () const
 Return the handle as a TiXmlText. This may return null.

TiXmlUnknownUnknown () const
 Return the handle as a TiXmlUnknown. This may return null;.


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 }


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.


The documentation for this class was generated from the following file:
Generated on Fri Apr 15 18:30:30 2005 for TinyXml by doxygen 1.3.6