net.sf.saxon.instruct

Class ElementCreator

Implemented Interfaces:
SourceLocator, EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator, TailCallReturner
Known Direct 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.

Field Summary

protected boolean
inheritNamespaces
The inheritNamespaces flag indicates that the namespace nodes on the element created by this instruction are to be inherited (copied) on the children of this element.
protected boolean
preservingTypes
Flag set to true if validation=preserve and no schema type supplied for validation

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

content

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Constructor Summary

ElementCreator()
Construct an ElementCreator.

Method Summary

protected void
checkContentSequence(StaticContext env)
Check statically whether the content of the element creates attributes or namespaces after creating any child nodes
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.
protected abstract void
outputNamespaceNodes(XPathContext context, Receiver receiver)
Callback to output namespace nodes for the new element.
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, checkContentSequence, computeCardinality, createsNewNodes, getBaseURI, getCardinality, getContentExpression, getSchemaType, getValidationMode, isLazyConstruction, isNamespaceSensitive, iterateSubExpressions, optimize, promoteInst, replaceSubExpression, setBaseURI, setContentExpression, setLazyConstruction, setSchemaType, setValidationMode, simplify, typeCheck

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

assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, createsNewNodes, dynamicError, evaluateAsString, evaluateItem, getImplementationMethod, getInstructionInfo, getInstructionNameCode, getItemType, getSourceLocator, isXSLT, iterate, process, processLeavingTail, promote, promoteInst, simplify

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

addToPathMap, adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Field Details

inheritNamespaces

protected boolean inheritNamespaces
The inheritNamespaces flag indicates that the namespace nodes on the element created by this instruction are to be inherited (copied) on the children of this element. That is, if this flag is false, the child elements must carry a namespace undeclaration for all the namespaces on the parent, unless they are redeclared in some way.

preservingTypes

protected boolean preservingTypes
Flag set to true if validation=preserve and no schema type supplied for validation

Constructor Details

ElementCreator

public ElementCreator()
Construct an ElementCreator. Exists for the benefit of subclasses.

Method Details

checkContentSequence

protected void checkContentSequence(StaticContext env)
            throws XPathException
Check statically whether the content of the element creates attributes or namespaces after creating any child nodes
Overrides:
checkContentSequence in interface ParentNodeConstructor
Parameters:
env - the static context
Throws:
XPathException -

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 interface Instruction
Returns:
a set of flags indicating static properties of this expression

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 interface Instruction

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.

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 interface Instruction

getItemType

public ItemType getItemType(TypeHierarchy th)
Get the item type of the value returned by this instruction
Overrides:
getItemType in interface Instruction
Parameters:
th - the type hierarchy cache
Returns:
the item type

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

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

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

iterateEvents

public EventIterator iterateEvents(XPathContext context)
            throws XPathException
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 interface 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

outputNamespaceNodes

protected abstract void outputNamespaceNodes(XPathContext context,
                                             Receiver receiver)
            throws XPathException
Callback to output namespace nodes for the new element.
Parameters:
context - The execution context
receiver - the Receiver where the namespace nodes are to be written
Throws:
XPathException -

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
Overrides:
processLeavingTail in interface Instruction
Parameters:
context - XPath dynamic evaluation context
Returns:
null (this instruction never returns a tail call)
Throws:
XPathException -

setValidationMode

public void setValidationMode(int mode)
Set the validation mode for the new element
Overrides:
setValidationMode in interface ParentNodeConstructor

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 interface Expression