net.sf.saxon.expr.instruct
Class ElementCreator

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.instruct.Instruction
          extended by net.sf.saxon.expr.instruct.ParentNodeConstructor
              extended by net.sf.saxon.expr.instruct.ElementCreator
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, DivisibleInstruction, TailCallReturner, SequenceIterable, InstructionInfo, Locator
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
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.expr.instruct.ParentNodeConstructor
content
 
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD
 
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, NodeInfo copiedNode)
          Determine (at run-time) the name code of the element being constructed
protected abstract  String getNewBaseURI(XPathContext context, NodeInfo copiedNode)
          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  EventIterator iterateEvents(XPathContext context, NodeInfo copiedNode)
           
protected abstract  void outputNamespaceNodes(XPathContext context, Receiver receiver, int nameCode, NodeInfo copiedNode)
          Callback to output namespace nodes for the new element.
 TailCall processLeavingTail(XPathContext context)
          Evaluate the instruction to produce a new element node.
protected  TailCall processLeavingTail(XPathContext context, NodeInfo copiedNode)
          Evaluate the instruction to produce a new element node.
 void processLeft(Stack<XPathContext> contextStack, Stack state)
          In streaming mode, process the first half of the instruction (to start a new document or element)
protected  void processLeft(Stack<XPathContext> contextStack, Stack state, NodeInfo copiedNode)
          In streaming mode, process the first half of the instruction (to start a new document or element)
 void processRight(Stack<XPathContext> contextStack, Stack state)
          In streaming mode, proecss the right half of the instruction (to end a new document or element)
 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.expr.instruct.ParentNodeConstructor
addToPathMap, computeCardinality, createsNewNodes, getBaseURI, getCardinality, getContentExpression, getSchemaType, getValidationMode, isLazyConstruction, isNamespaceSensitive, iterateSubExpressions, optimize, promoteInst, replaceSubExpression, setBaseURI, setContentExpression, setLazyConstruction, setSchemaType, simplify, typeCheck
 
Methods inherited from class net.sf.saxon.expr.instruct.Instruction
assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getExpressionName, getInstructionName, getInstructionNameCode, getIteratorFromProcessMethod, getSourceLocator, isXSLT, iterate, process, promote
 
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, explain, getColumnNumber, getColumnNumber, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateSameFocusSubExpressions, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, toString, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface javax.xml.transform.SourceLocator
getColumnNumber, getLineNumber, getPublicId, getSystemId
 

Field Detail

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 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

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

Specified by:
checkContentSequence in class ParentNodeConstructor
Parameters:
env - the static context
Throws:
XPathException

getNameCode

public abstract int getNameCode(XPathContext context,
                                NodeInfo copiedNode)
                         throws XPathException
Determine (at run-time) the name code of the element being constructed

Parameters:
context - the XPath dynamic evaluation context
copiedNode -
Returns:
the integer name code representing the element name
Throws:
XPathException - if a failure occurs

getNewBaseURI

protected abstract String getNewBaseURI(XPathContext context,
                                        NodeInfo copiedNode)
Get the base URI for the element being constructed

Parameters:
context - the XPath dynamic evaluation context
copiedNode - the node being copied (for xsl:copy), otherwise null
Returns:
the base URI of the constructed element

outputNamespaceNodes

protected abstract void outputNamespaceNodes(XPathContext context,
                                             Receiver receiver,
                                             int nameCode,
                                             NodeInfo copiedNode)
                                      throws XPathException
Callback to output namespace nodes for the new element. This method is responsible for ensuring that a namespace node is always generated for the namespace of the element name itself.

Parameters:
context - The execution context
receiver - the Receiver where the namespace nodes are to be written
nameCode - the name code of the element being created
copiedNode - the node being copied (for xsl:copy) or null otherwise
Throws:
XPathException

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

iterateEvents

protected EventIterator iterateEvents(XPathContext context,
                                      NodeInfo copiedNode)
                               throws XPathException
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
Specified by:
processLeavingTail in class Instruction
Parameters:
context - XPath dynamic evaluation context
Returns:
null (this instruction never returns a tail call)
Throws:
XPathException

processLeavingTail

protected final TailCall processLeavingTail(XPathContext context,
                                            NodeInfo copiedNode)
                                     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.

Parameters:
context - XPath dynamic evaluation context
copiedNode - null except in the case of xsl:copy, when it is the node being copied
Returns:
null (this instruction never returns a tail call)
Throws:
XPathException

processLeft

public void processLeft(Stack<XPathContext> contextStack,
                        Stack state)
                 throws XPathException
In streaming mode, process the first half of the instruction (to start a new document or element)

Parameters:
contextStack - the dynamic evaluation context
state - a stack on which the instruction can save state information for use during the corresponding
Throws:
XPathException

processLeft

protected final void processLeft(Stack<XPathContext> contextStack,
                                 Stack state,
                                 NodeInfo copiedNode)
                          throws XPathException
In streaming mode, process the first half of the instruction (to start a new document or element)

Parameters:
contextStack - the dynamic evaluation context
state - a stack on which the instruction can save state information for use during the corresponding
Throws:
XPathException

processRight

public void processRight(Stack<XPathContext> contextStack,
                         Stack state)
                  throws XPathException
In streaming mode, proecss the right half of the instruction (to end a new document or element)

Parameters:
contextStack -
state - a stack on which the instruction can save state information for use during the corresponding
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


Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.