Package net.sf.saxon.expr.instruct

Class ComputedElement

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.instruct.Instruction

net.sf.saxon.expr.instruct.ParentNodeConstructor

net.sf.saxon.expr.instruct.ElementCreator

net.sf.saxon.expr.instruct.ComputedElement

All Implemented Interfaces:

ExportAgent, InstructionWithComplexContent, TailCallReturner, ValidatingInstruction, Locatable, IdentityComparable, Traceable

public class ComputedElement
extends ElementCreator

An instruction representing an xsl:element element in an XSLT stylesheet, or a computed element constructor in XQuery. (In both cases, if the element name is expressed as a compile-time expression, then a FixedElement instruction is used instead.)

See Also:

FixedElement

Field Summary

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

contentOp, preservingTypes

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

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor	Description
ComputedElement(Expression elementName, Expression namespace, SchemaType schemaType, int validation, boolean inheritNamespaces, boolean allowQName)	Create an instruction that creates a new element node

Method Summary

Modifier and Type	Method	Description
void	checkPermittedContents(SchemaType parentType, boolean whole)	Check that any elements and attributes constructed or returned by this expression are acceptable in the content model of a given complex type.
Expression	copy(RebindingMap rebindings)	Copy an expression.
void	export(ExpressionPresenter out)	Diagnostic print of expression structure.
NodeName	getElementName(XPathContext context, NodeInfo copiedNode)	Callback from the superclass ElementCreator to get the nameCode for the element name
int	getInstructionNameCode()	Get the name of this instruction for diagnostic and tracing purposes
ItemType	getItemType()	Get the item type of the value returned by this instruction
Expression	getNameExp()	Get the expression used to compute the element name
Expression	getNamespaceExp()	Get the expression used to compute the namespace URI
NamespaceResolver	getNamespaceResolver()	Get the namespace resolver that provides the namespace bindings defined in the static context
java.lang.String	getNewBaseURI(XPathContext context, NodeInfo copiedNode)	Get the base URI for the element being constructed
boolean	isAllowNameAsQName()	Ask whether the name can be supplied as a QName.
java.lang.Iterable<Operand>	operands()	Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
void	outputNamespaceNodes(Outputter out, NodeName nodeName, NodeInfo copiedNode)	Callback to output namespace nodes for the new element.
protected void	setNameExp(Expression elementName)
protected void	setNamespaceExp(Expression namespace)
Expression	simplify()	Simplify an expression.
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)	Perform type checking of an expression and its subexpressions.

Methods inherited from class net.sf.saxon.expr.instruct.ElementCreator

checkContentSequence, computeSpecialProperties, getCardinality, getImplementationMethod, getStreamerName, isBequeathNamespacesToChildren, isInheritNamespacesFromParent, processLeavingTail, processLeavingTail, setBequeathNamespacesToChildren, setInheritanceFlags, setInheritNamespacesFromParent, suppressValidation

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

addToPathMap, allowExtractingCommonSubexpressions, alwaysCreatesNewNodes, computeCardinality, getContentExpression, getContentOperand, getSchemaType, getValidationAction, getValidationOptions, isLocal, isPreservingTypes, mayCreateNewNodes, optimize, setContentExpression, setNoNeedToStrip, setValidationAction

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

assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, evaluateItem, getExpressionName, getNetCost, getSourceLocator, isInstruction, isXSLT, iterate, process, someOperandCreatesNewNodes

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

adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, computeDependencies, computeHashCode, computeStaticProperties, dynamicError, effectiveBooleanValue, equals, evaluatePendingUpdates, explain, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, toPattern, toShortString, toString, typeCheckChildren, typeError, unordered, verifyParentPointers

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface net.sf.saxon.trace.Traceable

gatherProperties

Constructor Detail

ComputedElement

public ComputedElement(Expression elementName,
                       Expression namespace,
                       SchemaType schemaType,
                       int validation,
                       boolean inheritNamespaces,
                       boolean allowQName)

Create an instruction that creates a new element node

Parameters:

elementName - Expression that evaluates to produce the name of the element node as a lexical QName

namespace - Expression that evaluates to produce the namespace URI of the element node. Set to null if the namespace is to be deduced from the prefix of the elementName.

schemaType - The required schema type for the content

validation - Required validation mode (e.g. STRICT, LAX, SKIP)

inheritNamespaces - true if child elements automatically inherit the namespaces of their parent

allowQName - True if the elementName expression is allowed to return a QNameValue; false if

Method Detail

getNameExp

public Expression getNameExp()

Get the expression used to compute the element name

Returns:

the expression used to compute the element name

getNamespaceExp

public Expression getNamespaceExp()

Get the expression used to compute the namespace URI

Returns:

the expression used to compute the namespace URI

setNameExp

protected void setNameExp(Expression elementName)

setNamespaceExp

protected void setNamespaceExp(Expression namespace)

operands

public java.lang.Iterable<Operand> operands()

Description copied from class: Expression

Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()

If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

Specified by:

operands in class Instruction

Returns:

an iterator containing the sub-expressions of this expression

getNamespaceResolver

public NamespaceResolver getNamespaceResolver()

Get the namespace resolver that provides the namespace bindings defined in the static context

Returns:

the namespace resolver

simplify

public Expression simplify()
                    throws XPathException

Description copied from class: Expression

Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation simplifies its operands.

Overrides:

simplify in class Expression

Returns:

the simplified expression (or the original if unchanged, or if modified in-situ)

Throws:

XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException

Description copied from class: Expression

Perform type checking of an expression and its subexpressions. This is the second phase of static optimization.

This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.

Overrides:

typeCheck in class ParentNodeConstructor

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

copy

public Expression copy(RebindingMap rebindings)

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Parameters:

rebindings - a mutable list of (old binding, new binding) pairs that is used to update the bindings held in any local variable references that are copied.

Returns:

the copy of the original expression

getItemType

public ItemType getItemType()

Get the item type of the value returned by this instruction

Overrides:

getItemType in class ElementCreator

Returns:

the item type

checkPermittedContents

public void checkPermittedContents(SchemaType parentType,
                                   boolean whole)
                            throws XPathException

Check that any elements and attributes constructed or returned by this expression are acceptable in the content model of a given complex type. It's always OK to say yes, since the check will be repeated at run-time. The process of checking element and attribute constructors against the content model of a complex type also registers the type of content expected of those constructors, so the static validation can continue recursively.

Overrides:

checkPermittedContents in class Expression

Parameters:

parentType - the "given complex type": the method is checking that the nodes returned by this expression are acceptable members of the content model of this type

whole - if true, we want to check that the value of this expression satisfies the content model as a whole; if false we want to check that the value of the expression is acceptable as one part of the content

Throws:

XPathException - if the value delivered by this expression cannot be part of the content model of the given type

getElementName

public NodeName getElementName(XPathContext context,
                               NodeInfo copiedNode)
                        throws XPathException

Callback from the superclass ElementCreator to get the nameCode for the element name

Specified by:

getElementName in class ElementCreator

Parameters:

context - The evaluation context (not used)

copiedNode - Not applicable to this overload

Returns:

the name code for the element name

Throws:

XPathException - if a failure occurs

isAllowNameAsQName

public boolean isAllowNameAsQName()

Ask whether the name can be supplied as a QName. In practice this is true for XQuery, false for XSLT

Returns:

true if the name can be supplied as a QName

getNewBaseURI

public java.lang.String getNewBaseURI(XPathContext context,
                                      NodeInfo copiedNode)

Description copied from class: ElementCreator

Get the base URI for the element being constructed

Specified by:

getNewBaseURI in class ElementCreator

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

public void outputNamespaceNodes(Outputter out,
                                 NodeName nodeName,
                                 NodeInfo copiedNode)
                          throws XPathException

Callback to output namespace nodes for the new element.

Specified by:

outputNamespaceNodes in class ElementCreator

Parameters:

out - the Outputter where the namespace nodes are to be written

nodeName - The name of the element node being output

copiedNode - Where this is a copied node, the node being copied

Throws:

XPathException - if a dynamic error occurs

getInstructionNameCode

public int getInstructionNameCode()

Get the name of this instruction for diagnostic and tracing purposes

Overrides:

getInstructionNameCode in class Instruction

Returns:

a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace

export

public void export(ExpressionPresenter out)
            throws XPathException

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

export in interface ExportAgent

Specified by:

export in class Expression

Parameters:

out - the expression presenter used to display the structure

Throws:

XPathException - if the export fails, for example if an expression is found that won't work in the target environment.