net.sf.saxon.pattern

Class NodeTest

Implemented Interfaces:
ItemType, Serializable
Known Direct Subclasses:
AnyChildNodePattern, AnyNodeTest, CombinedNodeTest, ContentTypeTest, DocumentNodeTest, EmptySequenceTest, LocalNameTest, NamespaceTest, NameTest, NodeKindTest, SubstitutionGroupTest

public abstract class NodeTest
extends java.lang.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.iterateAxis(byte,NodeTest), it is possible to write a user-defined subclass of NodeTest that implements a single method, matches(int,int,int)

Author:
Michael H. Kay

Method Summary

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)
SchemaType
getContentType()
Get the content type allowed by this NodeTest (that is, the type annotation of the matched nodes).
abstract double
getDefaultPriority()
Determine the default priority of this node test when used on its own as a Pattern
int
getFingerprint()
Get the name of the nodes matched by this nodetest, if it matches a specific name.
int
getNodeKindMask()
Get a mask indicating which kinds of nodes this NodeTest can match.
ItemType
getPrimitiveItemType()
Get the primitive item type corresponding to this item type.
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.
IntHashSet
getRequiredNodeNames()
Get the set of node names allowed by this NodeTest.
ItemType
getSuperType(TypeHierarchy th)
Get the type from which this item type is derived by restriction.
boolean
isAtomicType()
Determine whether this item type is atomic (that is, whether it can ONLY match atomic values)
boolean
isNillable()
Determine whether the content type (if present) is nillable
abstract boolean
matches(int nodeKind, int fingerprint, int annotation)
Test whether this node test is satisfied by a given node.
boolean
matches(NodeInfo node)
Test whether this node test is satisfied by a given node.
boolean
matches(TinyTree tree, int nodeNr)
Test whether this node test is satisfied by a given node on a TinyTree.
boolean
matchesItem(Item item, boolean allowURIPromotion, Configuration config)
Test whether a given item conforms to this type.
String
toString(NamePool pool)
Display the type descriptor for diagnostics

Method Details

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)
Specified by:
getAtomizedItemType in interface ItemType

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<<Type.ELEMENT for element nodes, 1<<Type.TEXT for text nodes, and so on. The default implementation indicates that nodes of all kinds are matched.

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.
Specified by:
getPrimitiveItemType in interface ItemType

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.
Specified by:
getPrimitiveType in interface ItemType
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.

Specified by:
getSuperType in interface ItemType
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)
Specified by:
isAtomicType in interface ItemType
Returns:
false: this is not ANY_ATOMIC_TYPE or a subtype thereof

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 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 matches(int,int,int)
Parameters:
node - the node to be matched

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(NodeInfo)
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

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.
Specified by:
matchesItem in interface ItemType
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
Specified by:
toString in interface ItemType