Mezzanine::XML::TreeWalker Class Reference

Used to call a function OnEachNode member of the subtree of nodes descended from a specific node. More...

#include <treewalker.h>

Public Member Functions
	TreeWalker ()
	Default constructor, initializes depth, and can do little else without a fully implemented treewalker.
virtual	~TreeWalker ()
	Virtual deconstructor. Tears down a TreeWalker.
virtual bool	OnEachNode (Node &node)=0
	A Pure Virtual function that is expected to be implemented to create the desired behavior. More...
virtual bool	OnTraversalBegin (Node &node)
	Called by the root Node of the xml subtree when traversal begins. More...
virtual bool	OnTraversalEnd (Node &node)
	Called on the root Node of the xml subtree when traversal ends. More...

Protected Member Functions
int	Depth () const
	How many descendants deep are we during traversal. More...

Friends
class	Node

Detailed Description

Used to call a function OnEachNode member of the subtree of nodes descended from a specific node.

If you want to do a deep tree traversal, you'll either have to do it via a recursive function or some equivalent method or use a TreeWalker. This provides a helper for depth-first traversal of a subtree. In order to use it, you have to implement XML::TreeWalker interface and call XML::Node::Traverse() function.

• First, TreeWalker::OnTraversalBegin() is called with traversal root as its argument.
  
• Then, TreeWalker::OnEachNode() function is called for all nodes in the traversal subtree in depth first order, excluding the traversal root. Each Node is passed as an argument.
  
• Finally, TreeWalker::OnTraversalEnd() function is called with traversal root as its argument.
  
  If TreeWalker::OnTraversalBegin(), TreeWalker::OnTraversalEnd() or any of the TreeWalker::OnEachNode() calls return false, the traversal is terminated and false is returned as the traversal result; otherwise, the traversal results in true. Note that you don't have to override begin or end functions; their default implementations return true.
  
  You can get the node's depth relative to the traversal root at any point by calling TreeWalker::Depth() function.

Definition at line 83 of file treewalker.h.

Member Function Documentation

int Mezzanine::XML::TreeWalker::Depth ( ) const

protected

How many descendants deep are we during traversal.

Returns

This returns -1 if called from TreeWalker::OnTraversalBegin() or TreeWalker::OnTraversalEnd(), and returns 0-based depth if called from OnEachNode - depth is 0 for all children of the traversal root, 1 for all grandchildren, 2 for great-grandchildren and so on.

virtual bool Mezzanine::XML::TreeWalker::OnEachNode ( Node &  node)

pure virtual

A Pure Virtual function that is expected to be implemented to create the desired behavior.

Parameters

node	The curren node being trraversed.

This is called on every Node that is traversed except the root node of the traversed subtree. Can be used to perform sophisticated searches of a portion of the xml document, alter the document on a large scale, gather statistics, or just about any other behavior that requires touching many nodes.

Returns

if true Traversal is expected to continue, if false, then traversal ends and the Node::Traverse() that was called is expected to return false.

virtual bool Mezzanine::XML::TreeWalker::OnTraversalBegin ( Node &  node)

virtual

Called by the root Node of the xml subtree when traversal begins.

Parameters

node	The first node the Tree to traverse

By default this simply returns true, but is expected to be overridden with any desired behavior

Returns

True by default. If it returns false, then traversal ends and the Node::Traverse() that was called is expected to return false.

virtual bool Mezzanine::XML::TreeWalker::OnTraversalEnd ( Node &  node)

virtual

Called on the root Node of the xml subtree when traversal ends.

Parameters

node	The last node the Tree to traverse

By default this simply returns true, but is expected to be overridden with any desired behavior

Returns

True by default. If it returns false, then traversal ends and the Node::Traverse() that was called is expected to return false.

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

• /home/sqeaky/Code/Mezzanine/Mezzanine/src/XML/treewalker.h