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TreeWalker Class

TreeWalker
objects are used to navigate a document tree or subtree using the view of the document defined by their
whatToShow
flags and filter (if any). Any function which performs navigation using a
TreeWalker
will automatically support any view defined by a
TreeWalker
.
Omitting nodes from the logical view of a subtree can result in a structure that is substantially different from the same subtree in the complete, unfiltered document. Nodes that are siblings in the
TreeWalker
view may be children of different, widely separated nodes in the original view. For instance, consider a
NodeFilter
that skips all nodes except for Text nodes and the root node of a document. In the logical view that results, all text nodes will be siblings and appear as direct children of the root node, no matter how deeply nested the structure of the original document.
See also the Document Object Model (DOM) Level 2 Traversal and Range Specification. @since DOM Level 2

Namespace: SharpKit.Html

Base Types

System.Object

Constructors

Name Description
TreeWalker()

Properties

Name Description
currentNode The node at which the
TreeWalker
is currently positioned.
Alterations to the DOM tree may cause the current node to no longer be accepted by the
TreeWalker
's associated filter.
currentNode
may also be explicitly set to any node, whether or not it is within the subtree specified by the
root
node or would be accepted by the filter and
whatToShow
flags. Further traversal occurs relative to
currentNode
even if it is not part of the current view, by applying the filters in the requested direction; if no traversal is possible,
currentNode
is not changed.
expandEntityReferences The value of this flag determines whether the children of entity reference nodes are visible to the
TreeWalker
. If false, they and their descendants will be rejected. Note that this rejection takes precedence over
whatToShow
and the filter, if any.
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
TreeWalker
. 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.
filter The filter used to screen nodes.
root The
root
node of the
TreeWalker
, as specified when it was created.
whatToShow This attribute determines which node types are presented via the
TreeWalker
. 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.

Methods

Name Description
firstChild() Moves the
TreeWalker
to the first visible child of the current node, and returns the new node. If the current node has no visible children, returns
null
, and retains the current node.
lastChild() Moves the
TreeWalker
to the last visible child of the current node, and returns the new node. If the current node has no visible children, returns
null
, and retains the current node.
nextNode() Moves the
TreeWalker
to the next visible node in document order relative to the current node, and returns the new node. If the current node has no next node, or if the search for nextNode attempts to step upward from the
TreeWalker
's
root
node, returns
null
, and retains the current node.
nextSibling() Moves the
TreeWalker
to the next sibling of the current node, and returns the new node. If the current node has no visible next sibling, returns
null
, and retains the current node.
parentNode() Moves to and returns the closest visible ancestor node of the current node. If the search for
parentNode
attempts to step upward from the
TreeWalker
's
root
node, or if it fails to find a visible ancestor node, this method retains the current position and returns
null
.
previousNode() Moves the
TreeWalker
to the previous visible node in document order relative to the current node, and returns the new node. If the current node has no previous node, or if the search for
previousNode
attempts to step upward from the
TreeWalker
's
root
node, returns
null
, and retains the current node.
previousSibling() Moves the
TreeWalker
to the previous sibling of the current node, and returns the new node. If the current node has no visible previous sibling, returns
null
, and retains the current node.
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