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TiXmlHandle Class Reference

#include <tinyxml.hh>

List of all members.

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
        }

Definition at line 1463 of file tinyxml.hh.

Public Member Functions

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.

Definition at line 1467 of file tinyxml.hh.

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

Copy constructor.

Definition at line 1469 of file tinyxml.hh.

Member Function Documentation

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

Definition at line 1504 of file tinyxml.hh.

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]

Definition at line 1505 of file tinyxml.hh.

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.

Definition at line 1511 of file tinyxml.hh.

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

Definition at line 1501 of file tinyxml.hh.

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]

Definition at line 1502 of file tinyxml.hh.

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.

Definition at line 1509 of file tinyxml.hh.

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

Definition at line 1470 of file tinyxml.hh.

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

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

Definition at line 1513 of file tinyxml.hh.

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

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

Definition at line 1515 of file tinyxml.hh.

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