net.sf.saxon.instruct
Class ElementCreator

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.instruct.Instruction
          net.sf.saxon.instruct.ParentNodeConstructor
              net.sf.saxon.instruct.ElementCreator

All Implemented Interfaces:

Serializable, SourceLocator, EvaluableItem, SequenceIterable, TailCallReturner, InstructionInfoProvider

Direct Known Subclasses:

ComputedElement, Copy, FixedElement

public abstract class ElementCreator
extends ParentNodeConstructor

An instruction that creates an element node. There are two subtypes, FixedElement for use where the name is known statically, and Element where it is computed dynamically. To allow use in both XSLT and XQuery, the class acts both as an Instruction and as an Expression.

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

ElementCreator()
Construct an ElementCreator.

Method Summary

int	computeSpecialProperties() Get the static properties of this expression (other than its type).
Item	evaluateItem(XPathContext context) Evaluate the constructor, returning the constructed element node.
int[]	getActiveNamespaces() Callback to get a list of the intrinsic namespaces that need to be generated for the element.
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
ItemType	getItemType(TypeHierarchy th) Get the item type of the value returned by this instruction
abstract int	getNameCode(XPathContext context) Determine (at run-time) the name code of the element being constructed
abstract String	getNewBaseURI(XPathContext context) Get the base URI for the element being constructed
boolean	isInheritNamespaces() Determine whether the inherit namespaces flag is set
boolean	isPreservingTypes() Determine whether this elementCreator performs validation or strips type annotations
EventIterator	iterateEvents(XPathContext context) Deliver the result of the expression as a sequence of events.
TailCall	processLeavingTail(XPathContext context) Evaluate the instruction to produce a new element node.
void	setValidationMode(int mode) Set the validation mode for the new element
void	suppressValidation(int validationMode) Suppress validation on contained element constructors, on the grounds that the parent element is already performing validation.

Methods inherited from class net.sf.saxon.instruct.ParentNodeConstructor

addToPathMap, computeCardinality, createsNewNodes, getBaseURI, getCardinality, getContentExpression, getSchemaType, getValidationMode, isLazyConstruction, isNamespaceSensitive, iterateSubExpressions, optimize, replaceSubExpression, setBaseURI, setContentExpression, setLazyConstruction, setSchemaType, simplify, typeCheck

Methods inherited from class net.sf.saxon.instruct.Instruction

evaluateAsString, getInstructionInfo, getInstructionNameCode, getSourceLocator, isXSLT, iterate, process, promote

Methods inherited from class net.sf.saxon.expr.Expression

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, copy, display, doPromotion, effectiveBooleanValue, explain, explain, findParentOf, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, markTailFunctionCalls, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getLineNumber, getPublicId, getSystemId

Constructor Detail

ElementCreator

public ElementCreator()

Construct an ElementCreator. Exists for the benefit of subclasses.

Method Detail

getItemType

public ItemType getItemType(TypeHierarchy th)

Get the item type of the value returned by this instruction

Overrides:

getItemType in class Instruction

Parameters:

th - the type hierarchy cache

Returns:

the item type

isPreservingTypes

public boolean isPreservingTypes()

Determine whether this elementCreator performs validation or strips type annotations

Returns:

false if the instruction performs validation of the constructed output or if it strips type annotations, otherwise true

isInheritNamespaces

public boolean isInheritNamespaces()

Determine whether the inherit namespaces flag is set

Returns:

true if namespaces constructed on a parent element are to be inherited by its children

computeSpecialProperties

public int computeSpecialProperties()

Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.

Overrides:

computeSpecialProperties in class Instruction

Returns:

a set of flags indicating static properties of this expression

setValidationMode

public void setValidationMode(int mode)

Set the validation mode for the new element

Overrides:

setValidationMode in class ParentNodeConstructor

Parameters:

mode - the validation mode, for example Validation.STRICT

suppressValidation

public void suppressValidation(int validationMode)

Suppress validation on contained element constructors, on the grounds that the parent element is already performing validation. The default implementation does nothing.

Overrides:

suppressValidation in class Expression

Parameters:

validationMode - the kind of validation being performed on the parent expression

getNameCode

public abstract int getNameCode(XPathContext context)
                         throws XPathException

Determine (at run-time) the name code of the element being constructed

Parameters:

context - the XPath dynamic evaluation context

Returns:

the integer name code representing the element name

Throws:

XPathException - if a failure occurs

getNewBaseURI

public abstract String getNewBaseURI(XPathContext context)

Get the base URI for the element being constructed

Parameters:

context - the XPath dynamic evaluation context

Returns:

the base URI of the constructed element

getActiveNamespaces

public int[] getActiveNamespaces()
                          throws XPathException

Callback to get a list of the intrinsic namespaces that need to be generated for the element.

Returns:

an array of namespace codes, the codes either occupy the whole array or are terminated by a -1 entry. A result of null is equivalent to a zero-length array.

Throws:

XPathException

getImplementationMethod

public int getImplementationMethod()

An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is prefered. For instructions this is the process() method.

Overrides:

getImplementationMethod in class Instruction

Returns:

the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

iterateEvents

public EventIterator iterateEvents(XPathContext context)
                            throws XPathException

Description copied from class: Expression

Deliver the result of the expression as a sequence of events.

The events (of class PullEvent) are either complete items, or one of startElement, endElement, startDocument, or endDocument, known as semi-nodes. The stream of events may also include a nested EventIterator. If a start-end pair exists in the sequence, then the events between this pair represent the content of the document or element. The content sequence will have been processed to the extent that any attribute and namespace nodes in the content sequence will have been merged into the startElement event. Namespace fixup will have been performed: that is, unique prefixes will have been allocated to element and attribute nodes, and all namespaces will be declared by means of a namespace node in the startElement event or in an outer startElement forming part of the sequence. However, duplicate namespaces may appear in the sequence.

The content of an element or document may include adjacent or zero-length text nodes, atomic values, and nodes represented as nodes rather than broken down into events.

Overrides:

iterateEvents in class Expression

Parameters:

context - The dynamic evaluation context

Returns:

the result of the expression as an iterator over a sequence of PullEvent objects

Throws:

XPathException - if a dynamic error occurs during expression evaluation

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException

Evaluate the instruction to produce a new element node. This method is typically used when there is a parent element or document in a result tree, to which the new element is added.

Specified by:

processLeavingTail in interface TailCallReturner

Specified by:

processLeavingTail in class Instruction

Parameters:

context - XPath dynamic evaluation context

Returns:

null (this instruction never returns a tail call)

Throws:

XPathException

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate the constructor, returning the constructed element node. If lazy construction mode is in effect, then an UnconstructedParent object is returned instead.

Specified by:

evaluateItem in interface EvaluableItem

Overrides:

evaluateItem in class Instruction

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression