Class NodeDescendants
This supports two ways of traversing the tree, either using an iterator, or providing an object which visits each node in the tree in turn.
Note that the iterator()
and visitTree(uk.ac.starlink.util.NodeDescendants.Visitor)
methods
below share state -- namely the state which this object represents
-- so you should not use simultaneously the result of two such
method calls on the same object.
-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic interface
TheVisitor
processes a single node in a tree. -
Field Summary
FieldsModifier and TypeFieldDescriptionstatic final int
Indicates that all nodes should be included in a traversal of, or iteration through, a tree.static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
-
Constructor Summary
ConstructorsConstructorDescriptionNodeDescendants
(Node node) Creates a newNodeDescendant
object.NodeDescendants
(Node node, int whatToShow) Creates a newNodeDescendant
object. -
Method Summary
Modifier and TypeMethodDescriptioniterator()
Obtains an iterator which iterates over the nodes in the set of descendants.void
reset()
Sets the object back to its initial state.void
reset
(int whatToShow) Sets the object back to its initial state, but with a (possibly) different constraint on which nodes are included in the set.Visits each of the nodes in the tree.
-
Field Details
-
SHOW_ALL
public static final int SHOW_ALLIndicates that all nodes should be included in a traversal of, or iteration through, a tree. To visit only certain nodes, use one of the otherSHOW...
constants.Note: this mechanism is taken from the DOM2 Traversal specification, though it is not an implementation of that set of interfaces. As noted there, not all of the
SHOW...
values are useful, since not all of the associatedNode
types can appear as descendants of a Node, othe than in rather special circumstances. The constants are included here for completeness, however.- See Also:
-
SHOW_ELEMENT
public static final int SHOW_ELEMENT- See Also:
-
SHOW_ATTRIBUTE
public static final int SHOW_ATTRIBUTE- See Also:
-
SHOW_TEXT
public static final int SHOW_TEXT- See Also:
-
SHOW_CDATA_SECTION
public static final int SHOW_CDATA_SECTION- See Also:
-
SHOW_ENTITY_REFERENCE
public static final int SHOW_ENTITY_REFERENCE- See Also:
-
SHOW_ENTITY
public static final int SHOW_ENTITY- See Also:
-
SHOW_PROCESSING_INSTRUCTION
public static final int SHOW_PROCESSING_INSTRUCTION- See Also:
-
SHOW_COMMENT
public static final int SHOW_COMMENT- See Also:
-
SHOW_DOCUMENT
public static final int SHOW_DOCUMENT- See Also:
-
SHOW_DOCUMENT_TYPE
public static final int SHOW_DOCUMENT_TYPE- See Also:
-
SHOW_DOCUMENT_FRAGMENT
public static final int SHOW_DOCUMENT_FRAGMENT- See Also:
-
SHOW_NOTATION
public static final int SHOW_NOTATION- See Also:
-
-
Constructor Details
-
NodeDescendants
Creates a newNodeDescendant
object. Equivalent toNodeDescendant(node, SHOW_ALL)
.- Parameters:
node
- the node which is to be the root of the tree
-
NodeDescendants
Creates a newNodeDescendant
object. This represents the set of Nodes in the tree rooted at the given Node.You can configure the set to include only certain nodes. If the
whatToShow
parameter is given asSHOW_ALL
, then all nodes are returned. If the parameter has one of the otherSHOW_...
values, or more than one or'ed together (using|
), then only the indicated node types are included in the set, and returned by any iterator or examined by any visitor.For example, if you create the
NodeDescendant
using the constructor:NodeDescendants tree = new NodeDescendants (mynode, NodeDescendants.SHOW_ALL);
(which is equivalent to theNodeDescendants(Node)
constructor), then the set represents all the nodes in the tree which are reachable from the nodemynode
by thegetFirstChild
and similar methods. If, however, the object was constructed withNodeDescendants tree = new NodeDescendants (mynode, NodeDescendants.SHOW_TEXT|NodeDescendants.SHOW_CDATA_SECTION);
then all Text and CDATA nodes would be included in the set, and only these would be returned by the iterator or visited by the visitor.- Parameters:
node
- the node which is to be the root of the treewhatToShow
- code indicating which node types should be included in the set
-
-
Method Details
-
reset
public void reset()Sets the object back to its initial state. This allows you to extract a second iterator either after an earlier one has finished, or before. -
reset
public void reset(int whatToShow) Sets the object back to its initial state, but with a (possibly) different constraint on which nodes are included in the set.- Parameters:
whatToShow
- code indicating which node types should be included in the set. SeeNodeDescendants(Node,int)
-
visitTree
Visits each of the nodes in the tree. This method iterates through all the descendants of the given node, starting with that node, and presents each of them to the givenNodeVisitor
. If that object'svisitNode
method returns non-null, then the traversal is stopped and the returned object immediately returned as the value of this method. If thevisitNode
method always returns null and so the traversal completes, then the method returns null also.- Parameters:
v
- a visitor which has each node presented to it in turn
-
iterator
Obtains an iterator which iterates over the nodes in the set of descendants. The traversal happens in depth-first order.- Returns:
- an iterator which returns in turn the given node, then all of its descendants.
-