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openvrml::node_traverser Class Reference
[Nodes]

List of all members.

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Detailed Description

Traverse the children of each node in a node hierarchy only once.

The node_traverser provides a generalized traversal mechanism that avoids redundantly traversing branches of the node hierarchy. If a node occurs multiple places in a branch, the children of that node will be visted in the traversal only once.

For each node encountered in the traversal, node_traverser does the following:

1. Call node_traverser::on_entering.
2. Traverse descendants, if any.
3. Call node_traverser::on_leaving.

Concrete subclasses of node_traverser implement the on_entering and/or on_leaving member functions in order to perform some operation(s) on each node. The traversal can be ended prematurely by calling node_traverser::halt_traversal.

Public Member Functions
	node_traverser () throw (std::bad_alloc)
	Construct.
virtual	~node_traverser ()=0 throw ()
	Destroy.
void	traverse (node &n)
	Traverse a node.
void	traverse (const node_ptr &node)
	Traverse a node.
void	traverse (const std::vector< node_ptr > &nodes)
	Traverse a std::vector of nodes.
Protected Member Functions
void	halt_traversal () throw ()
	Halt the traversal.
bool	halted () throw ()
	Indicate whether the traversal has been halted.
Private Member Functions
virtual void	on_entering (node &n)
	Called for each node in the traversal before traversing the its descendants.
virtual void	on_leaving (node &n)
	Called for each node in the traversal after traversing the its descendants.
void	do_traversal (node &n)
	Traverse a node.
Private Attributes
std::set< node * >	traversed_nodes
	The set of nodes that have already been traversed.
bool	halt
	Flag to indicate if the traversal should be halted.

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Constructor & Destructor Documentation

openvrml::node_traverser::node_traverser

(

)

throw (std::bad_alloc)

Construct.

Exceptions:

std::bad_alloc

if memory allocation fails.

openvrml::node_traverser::~node_traverser

(

)

throw () [pure virtual]

Destroy.

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Member Function Documentation

void openvrml::node_traverser::traverse

(

node &

n

)

Traverse a node.

No guarantee is made about the state of the node_traverser instance in the event that this method throws.

In addition to std::bad_alloc, this function throws any exception thrown from on_entering or on_leaving.

Parameters:

n

the root node of the branch to traverse.

Exceptions:

std::bad_alloc

if memory allocation fails.

void openvrml::node_traverser::traverse

(

const node_ptr &

node

)

Traverse a node.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters:

node

the root node of the branch to traverse.

void openvrml::node_traverser::traverse

(

const std::vector< node_ptr > &

nodes

)

Traverse a std::vector of nodes.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters:

nodes

the root nodes of the branch to traverse.

void openvrml::node_traverser::halt_traversal

(

)

throw () [protected]

Halt the traversal.

If this method is called during a traversal, no more descendant nodes will be traversed. Note that if halt_traversal is called in the implementation of on_entering, on_leaving will still be called for the current node and any parent nodes (that is, any node for which on_entering has been called). Implementations of on_leaving can call node_traverser::halted to check whether the traversal has been halted.

bool openvrml::node_traverser::halted

(

)

throw () [protected]

Indicate whether the traversal has been halted.

This function is useful in implementations of on_leaving that need to check whether the traversal has been halted.

Returns:

true if the traversal has been halted; false otherwise.

void openvrml::node_traverser::on_entering

(

node &

n

)

[private, virtual]

Called for each node in the traversal before traversing the its descendants.

Parameters:

n

the node currently being traversed.

void openvrml::node_traverser::on_leaving

(

node &

n

)

[private, virtual]

Called for each node in the traversal after traversing the its descendants.

Parameters:

n

the node currently being traversed.

void openvrml::node_traverser::do_traversal

(

node &

n

)

[private]

Traverse a node.

For internal use only.

Parameters:

n

the node to traverse.

Exceptions:

std::bad_alloc

if memory allocation fails.

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Member Data Documentation

std::set< node * > openvrml::node_traverser::traversed_nodes [private]

The set of nodes that have already been traversed.

For internal use only.

bool openvrml::node_traverser::halt [private]

Flag to indicate if the traversal should be halted.

For internal use only.