Class XMLHandle

Defined in File tinyxml2.h

Class Documentation

class XMLHandle

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.FirstChildElement( "Document" ).FirstChildElement( "Element" ).FirstChildElement().NextSiblingElement();
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.

Public Functions

inline explicit XMLHandle(XMLNode *node): Create a handle from any node (at any depth of the tree.) This can be a null pointer.

inline explicit XMLHandle(XMLNode &node): Create a handle from a node.

inline XMLHandle(const XMLHandle &ref): Copy constructor.

inline XMLHandle &operator=(const XMLHandle &ref): Assignment.

inline XMLHandle FirstChild(): Get the first child of this handle.

inline XMLHandle FirstChildElement(const char *name = 0): Get the first child element of this handle.

inline XMLHandle LastChild(): Get the last child of this handle.

inline XMLHandle LastChildElement(const char *name = 0): Get the last child element of this handle.

inline XMLHandle PreviousSibling(): Get the previous sibling of this handle.

inline XMLHandle PreviousSiblingElement(const char *name = 0): Get the previous sibling element of this handle.

inline XMLHandle NextSibling(): Get the next sibling of this handle.

inline XMLHandle NextSiblingElement(const char *name = 0): Get the next sibling element of this handle.

inline XMLNode *ToNode(): Safe cast to XMLNode. This can return null.

inline XMLElement *ToElement(): Safe cast to XMLElement. This can return null.

inline XMLText *ToText(): Safe cast to XMLText. This can return null.

inline XMLUnknown *ToUnknown(): Safe cast to XMLUnknown. This can return null.

inline XMLDeclaration *ToDeclaration(): Safe cast to XMLDeclaration. This can return null.