net.sf.saxon.type

Interface ItemType

All Known Subinterfaces:

AtomicType, FunctionItemType, ItemType.WithSequenceTypeCache, PlainType, UnionType

All Known Implementing Classes:

AnyChildNodeTest, AnyFunctionType, AnyFunctionTypeWithAssertions, AnyItemType, AnyNodeTest, ArrayItemType, BuiltInAtomicType, CombinedNodeTest, ContentTypeTest, DocumentNodeTest, ErrorType, JavaExternalObjectType, LocalNameTest, MapType, MultipleNodeKindTest, NamespaceTest, NameTest, NodeKindTest, NodeTest, NumericType, SameNameTest, SchemaAttributeTest, SchemaElementTest, SpecificFunctionType, TupleItemType, UserAtomicType, UserUnionType

public interface ItemType

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

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	ItemType.WithSequenceTypeCache Extension of the ItemType interface implemented by some item types, to provide a cache of SequenceType objects based on this item type, with different occurrence indicators.

Method Summary

Modifier and Type	Method and Description
java.lang.String	generateJavaScriptItemTypeAcceptor(java.lang.String errorCode, int targetVersion) Generate Javascript code to convert a supplied Javascript value to this item type, if conversion is possible, or throw an error otherwise.
java.lang.String	generateJavaScriptItemTypeTest(ItemType knownToBe, int targetVersion) Generate Javascript code to test whether an item conforms to this item type
PlainType	getAtomizedItemType() Get the item type of the atomic values that will be produced when an item of this type is atomized
ItemType	getPrimitiveItemType() Get the primitive item type corresponding to this item type.
int	getPrimitiveType() Get the primitive type corresponding to this item type.
UType	getUType() Get the corresponding UType.
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, TypeHierarchy th) Test whether a given item conforms to this type
java.lang.String	toExportString() Return a string representation of this SequenceType suitable for use in export (SEF) files.
java.lang.String	toString()
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). Return false if this is a union type whose member types are not all known.

matches

boolean matches(Item item,
                TypeHierarchy th)
         throws XPathException

Test whether a given item conforms to this type

Parameters:

item - The item to be tested

th - The type hierarchy cache. Currently used only when matching function items.

Returns:

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

Throws:

XPathException

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

getUType

UType getUType()

Get the corresponding UType. A UType is a union of primitive item types.

Returns:

the smallest UType that subsumes this item type

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

toExportString

java.lang.String toExportString()

Return a string representation of this SequenceType suitable for use in export (SEF) files. The difference from the toString() method is that the representation will not contain references to anonymous types.

Returns:

the string representation as an instance of the XPath SequenceType construct, using only names that will be in-scope if the target environment imports the same schema as the source environment

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

generateJavaScriptItemTypeTest

java.lang.String generateJavaScriptItemTypeTest(ItemType knownToBe,
                                                int targetVersion)
                                         throws XPathException

Generate Javascript code to test whether an item conforms to this item type

Parameters:

knownToBe - An item type that the supplied item is known to conform to; the generated code can assume that the item is an instance of this type.

targetVersion - The version of Saxon-JS for which code is being generated. Currently either 1 or 2.

Returns:

a Javascript instruction or sequence of instructions, which can be used as the body of a Javascript function, and which returns a boolean indication whether the value of the variable "item" is an instance of this item type.

Throws:

XPathException - if JS code cannot be generated for this item type, for example because the test is schema-aware.

generateJavaScriptItemTypeAcceptor

java.lang.String generateJavaScriptItemTypeAcceptor(java.lang.String errorCode,
                                                    int targetVersion)
                                             throws XPathException

Generate Javascript code to convert a supplied Javascript value to this item type, if conversion is possible, or throw an error otherwise.

Parameters:

errorCode - the error to be thrown if conversion is not possible

targetVersion - the version of Saxon-JS for which code is being generated

Returns:

a Javascript instruction or sequence of instructions, which can be used as the body of a Javascript function, and which returns the result of conversion to this type, or throws an error if conversion is not possible. The variable "val" will hold the supplied Javascript value.

Throws:

XPathException

toString

java.lang.String toString()

Overrides:

toString in class java.lang.Object