tinyxml2::XMLHandle Class Reference

#include "tinyxml2.h"

Public Member Functions
	XMLHandle (XMLNode *node)
	Create a handle from any node (at any depth of the tree.) This can be a null pointer. More...
	XMLHandle (XMLNode &node)
	Create a handle from a node. More...
	XMLHandle (const XMLHandle &ref)
	Copy constructor. More...
XMLHandle	FirstChild ()
	Get the first child of this handle. More...
XMLHandle	FirstChildElement (const char *value=0)
	Get the first child element of this handle. More...
XMLHandle	LastChild ()
	Get the last child of this handle. More...
XMLHandle	LastChildElement (const char *_value=0)
	Get the last child element of this handle. More...
XMLHandle	NextSibling ()
	Get the next sibling of this handle. More...
XMLHandle	NextSiblingElement (const char *_value=0)
	Get the next sibling element of this handle. More...
XMLHandle &	operator= (const XMLHandle &ref)
	Assignment. More...
XMLHandle	PreviousSibling ()
	Get the previous sibling of this handle. More...
XMLHandle	PreviousSiblingElement (const char *_value=0)
	Get the previous sibling element of this handle. More...
XMLDeclaration *	ToDeclaration ()
	Safe cast to XMLDeclaration. This can return null. More...
XMLElement *	ToElement ()
	Safe cast to XMLElement. This can return null. More...
XMLNode *	ToNode ()
	Safe cast to XMLNode. This can return null. More...
XMLText *	ToText ()
	Safe cast to XMLText. This can return null. More...
XMLUnknown *	ToUnknown ()
	Safe cast to XMLUnknown. This can return null. More...

Detailed Description

A XMLHandle is a class that wraps a node pointer with null checks; this is an incredibly useful thing. Note that XMLHandle is not part of the TinyXML-2 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:

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

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

XMLHandle docHandle( &document );
XMLElement* child2 = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).FirstChild().NextSibling().ToElement();
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.

XMLHandle handleCopy = handle;

See also XMLConstHandle, which is the same as XMLHandle, but operates on const objects.

Constructor & Destructor Documentation

tinyxml2::XMLHandle::XMLHandle ( XMLNode *  node )

inline

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

tinyxml2::XMLHandle::XMLHandle ( XMLNode &  node )

inline

Create a handle from a node.

tinyxml2::XMLHandle::XMLHandle ( const XMLHandle &  ref )

inline

Copy constructor.

Member Function Documentation

XMLHandle tinyxml2::XMLHandle::FirstChild ( )

inline

Get the first child of this handle.

XMLHandle tinyxml2::XMLHandle::FirstChildElement ( const char *  value = 0 )

inline

Get the first child element of this handle.

XMLHandle tinyxml2::XMLHandle::LastChild ( )

inline

Get the last child of this handle.

XMLHandle tinyxml2::XMLHandle::LastChildElement ( const char *  _value = 0 )

inline

Get the last child element of this handle.

XMLHandle tinyxml2::XMLHandle::NextSibling ( )

inline

Get the next sibling of this handle.

XMLHandle tinyxml2::XMLHandle::NextSiblingElement ( const char *  _value = 0 )

inline

Get the next sibling element of this handle.

XMLHandle& tinyxml2::XMLHandle::operator= ( const XMLHandle &  ref )

inline

Assignment.

XMLHandle tinyxml2::XMLHandle::PreviousSibling ( )

inline

Get the previous sibling of this handle.

XMLHandle tinyxml2::XMLHandle::PreviousSiblingElement ( const char *  _value = 0 )

inline

Get the previous sibling element of this handle.

XMLDeclaration* tinyxml2::XMLHandle::ToDeclaration ( )

inline

Safe cast to XMLDeclaration. This can return null.

XMLElement* tinyxml2::XMLHandle::ToElement ( )

inline

Safe cast to XMLElement. This can return null.

XMLNode* tinyxml2::XMLHandle::ToNode ( )

inline

Safe cast to XMLNode. This can return null.

XMLText* tinyxml2::XMLHandle::ToText ( )

inline

Safe cast to XMLText. This can return null.

XMLUnknown* tinyxml2::XMLHandle::ToUnknown ( )

inline

Safe cast to XMLUnknown. This can return null.

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

• /builds/master-contrib_docs-mac/opencv_contrib/modules/datasets/include/opencv2/datasets/tinyxml2/tinyxml2.h