net.sf.saxon.type

Interface ItemType

All Superinterfaces:

Serializable

All Known Subinterfaces:

AtomicType, FunctionItemType, PlainType, UnionType

All Known Implementing Classes:

AnyChildNodeTest, AnyFunctionType, AnyItemType, AnyNodeTest, BuiltInAtomicType, CombinedNodeTest, ContentTypeTest, DocumentNodeTest, EmptySequenceTest, ErrorType, ExternalObjectType, LocalNameTest, MapType, NamespaceTest, NameTest, NodeKindTest, NodeTest, SchemaAttributeTest, SchemaElementTest, SpecificFunctionType, UserAtomicType, UserUnionType

public interface ItemType
extends Serializable

ItemType is an interface that allows testing of whether an Item conforms to an expected type. ItemType represents the types in the type hierarchy in the XPath model, as distinct from the schema model: an item type is either item() (matches everything), a node type (matches nodes), an atomic type (matches atomic values), or empty() (matches nothing). Atomic types, represented by the class AtomicType, are also instances of SimpleType in the schema type hierarchy. Node Types, represented by the class NodeTest, are also Patterns as used in XSLT.

Saxon assumes that apart from AnyItemType (which corresponds to item() and matches anything), every ItemType will be either an AtomicType, a NodeTest, or a FunctionItemType. User-defined implementations of ItemType must therefore extend one of those three classes/interfaces.

See Also:

AtomicType, NodeTest, FunctionItemType

Method Summary

Methods

Modifier and Type	Method and Description
PlainType	getAtomizedItemType() Get the item type of the atomic values that will be produced when an item of this type is atomized
double	getDefaultPriority() Determine the default priority of this item type when used on its own as a Pattern
ItemType	getPrimitiveItemType() Get the primitive item type corresponding to this item type.
int	getPrimitiveType() Get the primitive type corresponding to this item type.
ItemType	getSuperType(TypeHierarchy th) Get the type from which this item type is derived by restriction.
boolean	isAtomicType() Determine whether this item type is an atomic type
boolean	isAtomizable() Ask whether values of this type are atomizable
boolean	isPlainType() Determine whether this item type is a plain type (that is, whether it can ONLY match atomic values)
boolean	matches(Item item, XPathContext context) Test whether a given item conforms to this type
boolean	matchesItem(Item item, boolean allowURIPromotion, Configuration config) Test whether a given item conforms to this type
void	visitNamedSchemaComponents(SchemaComponentVisitor visitor) Visit all the schema components used in this ItemType definition

Method Detail

isAtomicType

boolean isAtomicType()

Determine whether this item type is an atomic type

Returns:

true if this is ANY_ATOMIC_TYPE or a subtype thereof

isPlainType

boolean isPlainType()

Determine whether this item type is a plain type (that is, whether it can ONLY match atomic values)

Returns:

true if this is ANY_ATOMIC_TYPE or a subtype thereof, or a "plain" union type (that is, unions of atomic types that impose no further restrictions)

matches

boolean matches(Item item,
              XPathContext context)

Test whether a given item conforms to this type

Parameters:

item - The item to be tested

context - the XPath dynamic evaluation context

Returns:

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

matchesItem

boolean matchesItem(Item item,
                  boolean allowURIPromotion,
                  Configuration config)

Test whether a given item conforms to this type

Parameters:

item - The item to be tested

allowURIPromotion - if a URI value is to be treated as a string

config - the Saxon configuration

Returns:

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

getSuperType

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()

getPrimitiveItemType

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 and union types 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, xs:dayTimeDuration, and xs:yearMonthDuration are considered to be primitive types.

Returns:

the corresponding primitive type

getPrimitiveType

int getPrimitiveType()

Get the primitive 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 BuiltInAtomicType.ANY_ATOMIC. 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.

Returns:

the integer fingerprint of the corresponding primitive type

getDefaultPriority

double getDefaultPriority()

Determine the default priority of this item type when used on its own as a Pattern

Returns:

the default priority

getAtomizedItemType

PlainType getAtomizedItemType()

Get the item type of the atomic values that will be produced when an item of this type is atomized

Returns:

the best available item type of the atomic values that will be produced when an item of this type is atomized, or null if it is known that atomization will throw an error.

isAtomizable

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, or function items, in which case return false

visitNamedSchemaComponents

void visitNamedSchemaComponents(SchemaComponentVisitor visitor)
                                throws XPathException

Visit all the schema components used in this ItemType definition

Parameters:

visitor - the visitor class to be called when each component is visited

Throws:

XPathException - if an error occurs