class Poco::XML::NodeIterator

Overview

Iterators are used to step through a set of nodes, e.g. More…

#include <NodeIterator.h>

class NodeIterator
{
public:
    // construction

    NodeIterator(
        Node* root,
        unsigned long whatToShow,
        NodeFilter* pFilter = 0
        );

    NodeIterator(const NodeIterator& iterator);

    // methods

    NodeIterator&
    operator=(const NodeIterator& iterator);

    Node*
    root() const;

    unsigned long
    whatToShow() const;

    NodeFilter*
    filter() const;

    bool
    expandEntityReferences() const;

    Node*
    nextNode();

    Node*
    previousNode();

    Node*
    currentNodeNP() const;

    void
    detach();

protected:
    // methods

    bool
    accept(Node* pNode) const;

    Node*
    next() const;

    Node*
    previous() const;

    Node*
    last();
};

Detailed Documentation

Iterators are used to step through a set of nodes, e.g.

the set of nodes in a NodeList, the document subtree governed by a particular Node, the results of a query, or any other set of nodes. The set of nodes to be iterated is determined by the implementation of the NodeIterator. DOM Level 2 specifies a single NodeIterator implementation for document-order traversal of a document subtree.

A NodeIterator can be directly instantiated using one of its constructors - the DocumentTraversal interface is not needed and therefore not implemented. Unlike most other DOM classes, NodeIterator supports value semantics.

If the NodeIterator ‘s current node is removed from the document, the result of calling any of the movement methods is undefined. This behavior does not conform to the DOM Level 2 Traversal specification.

Construction

NodeIterator(
    Node* root,
    unsigned long whatToShow,
    NodeFilter* pFilter = 0
    )

Creates a NodeIterator over the subtree rooted at the specified node.

NodeIterator(const NodeIterator& iterator)

Creates a NodeIterator by copying another NodeIterator.

Methods

NodeIterator&
operator=(const NodeIterator& iterator)

Assignment operator.

Node*
root() const

The root node of the NodeIterator, as specified when it was created.

unsigned long
whatToShow() const

This attribute determines which node types are presented via the iterator.

The available set of constants is defined in the NodeFilter interface. Nodes not accepted by whatToShow will be skipped, but their children may still be considered. Note that this skip takes precedence over the filter, if any.

NodeFilter*
filter() const

The NodeFilter used to screen nodes.

bool
expandEntityReferences() const

The value of this flag determines whether the children of entity reference nodes are visible to the iterator.

If false, they and their descendants will be rejected. Note that this rejection takes precedence over whatToShow and the filter. Also note that this is currently the only situation where NodeIterators may reject a complete subtree rather than skipping individual nodes.

To produce a view of the document that has entity references expanded and does not expose the entity reference node itself, use the whatToShow flags to hide the entity reference node and set expandEntityReferences to true when creating the iterator. To produce a view of the document that has entity reference nodes but no entity expansion, use the whatToShow flags to show the entity reference node and set expandEntityReferences to false.

This implementation does not support entity reference expansion and thus always returns false.

Node*
nextNode()

Returns the next node in the set and advances the position of the iterator in the set.

After a NodeIterator is created, the first call to nextNode() returns the first node in the set.

Node*
previousNode()

Returns the previous node in the set and moves the position of the NodeIterator backwards in the set.

Node*
currentNodeNP() const

Returns the current node in the set.

Leaves the NodeIterator unchanged.

Warning: This is a proprietary extension to the DOM Level 2 NodeIterator interface.

void
detach()

Detaches the NodeIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.

After detach has been invoked, calls to nextNode or previousNode will raise the exception INVALID_STATE_ERR.