net.sf.saxon.pattern

Class NodeTest

public abstract class NodeTest extends Object implements ItemType, Serializable

A NodeTest is a simple kind of pattern that enables a context-free test of whether a node has a particular name. There are several kinds of node test: a full name test, a prefix test, and an "any node of a given type" test, an "any node of any type" test, a "no nodes" test (used, e.g. for "@comment()").

As well as being used to support XSLT pattern matching, NodeTests act as predicates in axis steps, and also act as item types for type matching.

For use in user-written application calling NodeInfo, it is possible to write a user-defined subclass of NodeTest that implements a single method, NodeTest

Author: Michael H. Kay

Method Summary
AtomicTypegetAtomizedItemType()
Get the item type of the atomic values that will be produced when an item of this type is atomized (assuming that atomization succeeds)
SchemaTypegetContentType()
Get the content type allowed by this NodeTest (that is, the type annotation of the matched nodes).
abstract doublegetDefaultPriority()
Determine the default priority of this node test when used on its own as a Pattern
intgetFingerprint()
Get the name of the nodes matched by this nodetest, if it matches a specific name.
intgetNodeKindMask()
Get a mask indicating which kinds of nodes this NodeTest can match.
ItemTypegetPrimitiveItemType()
Get the primitive item type corresponding to this item type.
intgetPrimitiveType()
Get the basic kind of object that this ItemType matches: for a NodeTest, this is the kind of node, or Type.Node if it matches different kinds of nodes.
IntHashSetgetRequiredNodeNames()
Get the set of node names allowed by this NodeTest.
ItemTypegetSuperType(TypeHierarchy th)
Get the type from which this item type is derived by restriction.
booleanisAtomicType()
Determine whether this item type is atomic (that is, whether it can ONLY match atomic values)
booleanisAtomizable()
Ask whether values of this type are atomizable
booleanisNillable()
Determine whether the content type (if present) is nillable
booleanmatches(TinyTree tree, int nodeNr)
Test whether this node test is satisfied by a given node on a TinyTree.
abstract booleanmatches(int nodeKind, int fingerprint, int annotation)
Test whether this node test is satisfied by a given node.
booleanmatches(NodeInfo node)
Test whether this node test is satisfied by a given node.
booleanmatchesItem(Item item, boolean allowURIPromotion, Configuration config)
Test whether a given item conforms to this type.
StringtoString(NamePool pool)
Display the type descriptor for diagnostics

Method Detail

getAtomizedItemType

public AtomicType getAtomizedItemType()
Get the item type of the atomic values that will be produced when an item of this type is atomized (assuming that atomization succeeds)

getContentType

public SchemaType getContentType()
Get the content type allowed by this NodeTest (that is, the type annotation of the matched nodes). Return AnyType if there are no restrictions. The default implementation returns AnyType.

getDefaultPriority

public abstract double getDefaultPriority()
Determine the default priority of this node test when used on its own as a Pattern

getFingerprint

public int getFingerprint()
Get the name of the nodes matched by this nodetest, if it matches a specific name. Return -1 if the node test matches nodes of more than one name

getNodeKindMask

public int getNodeKindMask()
Get a mask indicating which kinds of nodes this NodeTest can match. This is a combination of bits: 1<

getPrimitiveItemType

public ItemType getPrimitiveItemType()
Get the primitive item type corresponding to this item type. For item(), this is Type.ITEM. For node(), it is Type.NODE. For specific node kinds, it is the value representing the node kind, for example Type.ELEMENT. For anyAtomicValue it is Type.ATOMIC_VALUE. For numeric it is Type.NUMBER. For other atomic types it is the primitive type as defined in XML Schema, except that INTEGER is considered to be a primitive type.

getPrimitiveType

public int getPrimitiveType()
Get the basic kind of object that this ItemType matches: for a NodeTest, this is the kind of node, or Type.Node if it matches different kinds of nodes.

Returns: the node kind matched by this node test

getRequiredNodeNames

public IntHashSet getRequiredNodeNames()
Get the set of node names allowed by this NodeTest. This is returned as a set of Integer fingerprints. A null value indicates that all names are permitted (i.e. that there are no constraints on the node name. The default implementation returns null.

getSuperType

public ItemType getSuperType(TypeHierarchy th)
Get the type from which this item type is derived by restriction. This is the supertype in the XPath type heirarchy, as distinct from the Schema base type: this means that the supertype of xs:boolean is xs:anyAtomicType, whose supertype is item() (rather than xs:anySimpleType).

In fact the concept of "supertype" is not really well-defined, because the types form a lattice rather than a hierarchy. The only real requirement on this function is that it returns a type that strictly subsumes this type, ideally as narrowly as possible.

Parameters: th the type hierarchy cache

Returns: the supertype, or null if this type is item()

isAtomicType

public boolean isAtomicType()
Determine whether this item type is atomic (that is, whether it can ONLY match atomic values)

Returns: false: this is not ANY_ATOMIC_TYPE or a subtype thereof

isAtomizable

public boolean isAtomizable()
Ask whether values of this type are atomizable

Returns: true unless it is known that these items will be elements with element-only content, in which case return false

isNillable

public boolean isNillable()
Determine whether the content type (if present) is nillable

Returns: true if the content test (when present) can match nodes that are nilled

matches

public boolean matches(TinyTree tree, int nodeNr)
Test whether this node test is satisfied by a given node on a TinyTree. The node must be a document, element, text, comment, or processing instruction node. This method is provided so that when navigating a TinyTree a node can be rejected without actually instantiating a NodeInfo object. The default implementation instantiates the node and then calls the method matches

Parameters: tree the TinyTree containing the node nodeNr the number of the node within the TinyTree

Returns: true if the node matches the NodeTest, otherwise false

matches

public abstract boolean matches(int nodeKind, int fingerprint, int annotation)
Test whether this node test is satisfied by a given node. This method is only fully supported for a subset of NodeTests, because it doesn't provide all the information needed to evaluate all node tests. In particular (a) it can't be used to evaluate a node test of the form element(N,T) or schema-element(E) where it is necessary to know whether the node is nilled, and (b) it can't be used to evaluate a node test of the form document-node(element(X)). This in practice means that it is used (a) to evaluate the simple node tests found in the XPath 1.0 subset used in XML Schema, and (b) to evaluate node tests where the node kind is known to be an attribute.

Parameters: nodeKind The kind of node to be matched fingerprint identifies the expanded name of the node to be matched. The value should be -1 for a node with no name. annotation The actual content type of the node

matches

public boolean matches(NodeInfo node)
Test whether this node test is satisfied by a given node. This alternative method is used in the case of nodes where calculating the fingerprint is expensive, for example DOM or JDOM nodes. The default implementation calls the method NodeTest

Parameters: node the node to be matched

matchesItem

public boolean matchesItem(Item item, boolean allowURIPromotion, Configuration config)
Test whether a given item conforms to this type. This implements a method of the ItemType interface.

Parameters: item The item to be tested allowURIPromotion config

Returns: true if the item is an instance of this type; false otherwise

toString

public String toString(NamePool pool)
Display the type descriptor for diagnostics