Package net.sf.saxon.instruct
Class ComputedAttribute
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.instruct.Instruction
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- net.sf.saxon.instruct.SimpleNodeConstructor
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- net.sf.saxon.instruct.AttributeCreator
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- net.sf.saxon.instruct.ComputedAttribute
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,EvaluableItem
,SequenceIterable
,TailCallReturner
,InstructionInfo
,org.xml.sax.Locator
public final class ComputedAttribute extends AttributeCreator
An instruction derived from an xsl:attribute element in stylesheet, or from an attribute constructor in XQuery, in cases where the attribute name is not known statically- See Also:
- Serialized Form
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Field Summary
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Fields inherited from class net.sf.saxon.instruct.SimpleNodeConstructor
select
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Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
Constructors Constructor Description ComputedAttribute(Expression attributeName, Expression namespace, NamespaceResolver nsContext, int validationAction, SimpleType schemaType, int annotation, boolean allowNameAsQName)
Construct an Attribute instruction
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
checkPermittedContents(SchemaType parentType, StaticContext env, 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.int
computeSpecialProperties()
Get the static properties of this expression (other than its type).Expression
copy()
Copy an expression.int
evaluateNameCode(XPathContext context)
Determine the name to be used for the attribute, as an integer name codevoid
explain(ExpressionPresenter out)
Diagnostic print of expression structure.int
getCardinality()
Get the static cardinality of this expressionint
getInstructionNameCode()
Get the name of this instructionItemType
getItemType(TypeHierarchy th)
Get the static type of this expressionExpression
getNameExpression()
Get the expression used to compute the name of the attributeExpression
getNamespaceExpression()
Get the expression used to compute the namespace part of the name of the attributeNamespaceResolver
getNamespaceResolver()
Get the namespace resolver used to resolve any prefix in the name of the attributejava.util.Iterator
iterateSubExpressions()
Get the subexpressions of this expressionvoid
localTypeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Method to perform type-checking specific to the kind of instructionExpression
optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.TailCall
processLeavingTail(XPathContext context)
Process this instructionprotected void
promoteInst(PromotionOffer offer)
Offer promotion for subexpressions.boolean
replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpressionvoid
setRejectDuplicates()
Indicate that two attributes with the same name are not acceptable.Expression
simplify(ExpressionVisitor visitor)
Simplify an expression.-
Methods inherited from class net.sf.saxon.instruct.AttributeCreator
getAnnotation, getOptions, getSchemaType, getValidationAction, setAnnotation, setNoSpecialChars, setOptions, setSchemaType, setValidationAction
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Methods inherited from class net.sf.saxon.instruct.SimpleNodeConstructor
checkContent, computeCardinality, createsNewNodes, evaluateItem, expandChildren, getSelect, iterate, setSelect, typeCheck
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Methods inherited from class net.sf.saxon.instruct.Instruction
assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getImplementationMethod, getSourceLocator, isXSLT, process, promote
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Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, findParentOf, getColumnNumber, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError
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Constructor Detail
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ComputedAttribute
public ComputedAttribute(Expression attributeName, Expression namespace, NamespaceResolver nsContext, int validationAction, SimpleType schemaType, int annotation, boolean allowNameAsQName)
Construct an Attribute instruction- Parameters:
attributeName
- An expression to calculate the attribute namenamespace
- An expression to calculate the attribute namespacensContext
- a NamespaceContext object containing the static namespace context of the stylesheet instructionvalidationAction
- e.g. validation=strict, lax, strip, preserveschemaType
- Type against which the attribute must be validated. This must not be a namespace-sensitive type; it is the caller's responsibility to check this.annotation
- Integer code identifying the type named in thetype
attributeallowNameAsQName
- true if the attributeName expression is allowed to evaluate to a value of type xs:QName (true in XQuery, false in XSLT)
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Method Detail
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setRejectDuplicates
public void setRejectDuplicates()
Indicate that two attributes with the same name are not acceptable. (This option is set in XQuery, but not in XSLT)- Overrides:
setRejectDuplicates
in classAttributeCreator
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getInstructionNameCode
public int getInstructionNameCode()
Get the name of this instruction- Overrides:
getInstructionNameCode
in classInstruction
- Returns:
- a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace
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getNameExpression
public Expression getNameExpression()
Get the expression used to compute the name of the attribute- Returns:
- the expression used to compute the name of the attribute
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getNamespaceExpression
public Expression getNamespaceExpression()
Get the expression used to compute the namespace part of the name of the attribute- Returns:
- the expression used to compute the namespace part of the name of the attribute
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getNamespaceResolver
public NamespaceResolver getNamespaceResolver()
Get the namespace resolver used to resolve any prefix in the name of the attribute- Returns:
- the namespace resolver if one has been saved; or null otherwise
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getItemType
public ItemType getItemType(TypeHierarchy th)
Get the static type of this expression- Overrides:
getItemType
in classInstruction
- Parameters:
th
- the type hierarchy cache- Returns:
- the static type of the item returned by this expression
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getCardinality
public int getCardinality()
Get the static cardinality of this expression- Overrides:
getCardinality
in classExpression
- Returns:
- the static cardinality (exactly one)
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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 classSimpleNodeConstructor
- Returns:
- a set of flags indicating static properties of this expression
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simplify
public Expression simplify(ExpressionVisitor visitor) throws XPathException
Description copied from class:Instruction
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.- Overrides:
simplify
in classSimpleNodeConstructor
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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localTypeCheck
public void localTypeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Description copied from class:SimpleNodeConstructor
Method to perform type-checking specific to the kind of instruction- Specified by:
localTypeCheck
in classSimpleNodeConstructor
- Parameters:
visitor
- an expression visitorcontextItemType
- the static type of the context item- Throws:
XPathException
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optimize
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Description copied from class:Expression
Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.
- Overrides:
optimize
in classSimpleNodeConstructor
- Parameters:
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
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copy
public Expression copy()
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
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iterateSubExpressions
public java.util.Iterator iterateSubExpressions()
Get the subexpressions of this expression- Overrides:
iterateSubExpressions
in classSimpleNodeConstructor
- Returns:
- an iterator over the subexpressions
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replaceSubExpression
public boolean replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression- Overrides:
replaceSubExpression
in classSimpleNodeConstructor
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression- Returns:
- true if the original subexpression is found
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promoteInst
protected void promoteInst(PromotionOffer offer) throws XPathException
Offer promotion for subexpressions. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.- Overrides:
promoteInst
in classSimpleNodeConstructor
- Parameters:
offer
- details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression- Throws:
XPathException
- if any error is detected
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checkPermittedContents
public void checkPermittedContents(SchemaType parentType, StaticContext env, 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 classExpression
- 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 typeenv
- the static contextwhole
- 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
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processLeavingTail
public TailCall processLeavingTail(XPathContext context) throws XPathException
Process this instruction- Specified by:
processLeavingTail
in interfaceTailCallReturner
- Specified by:
processLeavingTail
in classInstruction
- Parameters:
context
- the dynamic context of the transformation- Returns:
- a TailCall to be executed by the caller, always null for this instruction
- Throws:
XPathException
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evaluateNameCode
public int evaluateNameCode(XPathContext context) throws XPathException
Determine the name to be used for the attribute, as an integer name code- Overrides:
evaluateNameCode
in classSimpleNodeConstructor
- Parameters:
context
- Dynamic evaluation context- Returns:
- the integer name code for the attribute name
- Throws:
XPathException
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explain
public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
explain
in classExpression
- Parameters:
out
- the expression presenter used to display the structure
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