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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 Methods
	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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