Package net.sf.saxon.expr
Class InstanceOfExpression
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.UnaryExpression
net.sf.saxon.expr.InstanceOfExpression
- All Implemented Interfaces:
ExportAgent
,Locatable
,IdentityComparable
,Traceable
InstanceOf Expression: implements "Expr instance of data-type"
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
Elaborator for aninstance of
expression -
Field Summary
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
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Constructor Summary
ConstructorsConstructorDescriptionInstanceOfExpression
(Expression source, SequenceType target) Construct an "instance of" expression in the form "source instance of target" -
Method Summary
Modifier and TypeMethodDescriptionprotected int
Determine the cardinalityprotected int
get HashCode for comparing two expressions.copy
(RebindingMap rebindings) Copy an expression.boolean
effectiveBooleanValue
(XPathContext context) Evaluate the expression as a booleanboolean
Is this expression the same as another expression?evaluateItem
(XPathContext context) Evaluate the expressionvoid
Diagnostic print of expression structure.Make an elaborator for this expressionGet a name identifying the kind of expression, in terms meaningful to a user.int
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().Determine the data type of the result of the InstanceOf expressionprotected OperandRole
Get the usage (in terms of streamability analysis) of the single operandint
Get the cardinality that we are testing for membership ofGet the item type that we are testing for membership ofgetStaticUType
(UType contextItemType) Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.Get the (partial) name of a class that supports streaming of this kind of expressionoptimize
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform optimisation of an expression and its subexpressions.Produce a short string identifying the expression for use in error messagestoString()
The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.typeCheck
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expressionMethods inherited from class net.sf.saxon.expr.UnaryExpression
computeSpecialProperties, displayOperator, emitExtraAttributes, getBaseExpression, getOperand, operands, setBaseExpression
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dispatchTailCall, dynamicError, evaluateAsString, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, makeElaborator, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, supportsLazyEvaluation, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers, withLocation
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
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Constructor Details
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InstanceOfExpression
Construct an "instance of" expression in the form "source instance of target"- Parameters:
source
- the expression whose type is to be testedtarget
- the type against which it is tested
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Method Details
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getOperandRole
Description copied from class:UnaryExpression
Get the usage (in terms of streamability analysis) of the single operand- Specified by:
getOperandRole
in classUnaryExpression
- Returns:
- the operand usage
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getRequiredItemType
Get the item type that we are testing for membership of- Returns:
- the item type
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getRequiredCardinality
public int getRequiredCardinality()Get the cardinality that we are testing for membership of- Returns:
- the required cardinality
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException Type-check the expression- Overrides:
typeCheck
in classUnaryExpression
- Parameters:
visitor
- an expression visitorcontextInfo
- Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.- Returns:
- the checked expression
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
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optimize
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException Perform optimisation of an expression and its subexpressions.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 classUnaryExpression
- Parameters:
visitor
- an expression visitorcontextInfo
- 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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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 provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.- Specified by:
getImplementationMethod
in classExpression
- Returns:
- the implementation method, for example
Expression.ITERATE_METHOD
orExpression.EVALUATE_METHOD
orExpression.PROCESS_METHOD
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equals
Is this expression the same as another expression?- Overrides:
equals
in classUnaryExpression
- Parameters:
other
- the other operand; the result is false if this is not an Expression- Returns:
- true if the other operand is an expression and if it can be determined that the two expressions are equivalent, in the sense that they will always return the same result.
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computeHashCode
protected int computeHashCode()get HashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.- Overrides:
computeHashCode
in classUnaryExpression
- Returns:
- a computed hash code
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computeCardinality
protected int computeCardinality()Determine the cardinality- Overrides:
computeCardinality
in classUnaryExpression
- Returns:
- the computed cardinality, as one of the values
StaticProperty.ALLOWS_ZERO_OR_ONE
,StaticProperty.EXACTLY_ONE
,StaticProperty.ALLOWS_ONE_OR_MORE
,StaticProperty.ALLOWS_ZERO_OR_MORE
. May also returnStaticProperty.ALLOWS_ZERO
if the result is known to be an empty sequence, orStaticProperty.ALLOWS_MANY
if if is known to return a sequence of length two or more.
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copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Parameters:
rebindings
- variable references that need to be rebound- Returns:
- the copy of the original expression
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getItemType
Determine the data type of the result of the InstanceOf expression- Overrides:
getItemType
in classUnaryExpression
- Returns:
- the item type of the items in the result sequence, insofar as this is known statically.
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getStaticUType
Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.- Overrides:
getStaticUType
in classExpression
- Parameters:
contextItemType
- the statically-inferred type of the context item- Returns:
- the static item type of the expression according to the XSLT 3.0 defined rules
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evaluateItem
Evaluate the expression- Overrides:
evaluateItem
in classExpression
- 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
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effectiveBooleanValue
Evaluate the expression as a boolean- Overrides:
effectiveBooleanValue
in classExpression
- Parameters:
context
- The context in which the expression is to be evaluated- Returns:
- the effective boolean value
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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getExpressionName
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionName
in classExpression
- Returns:
- a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in export() output displaying the expression.
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export
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
export
in interfaceExportAgent
- Overrides:
export
in classUnaryExpression
- 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.
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toString
The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax- Overrides:
toString
in classUnaryExpression
- Returns:
- a representation of the expression as a string
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toShortString
Produce a short string identifying the expression for use in error messages- Overrides:
toShortString
in classUnaryExpression
- Returns:
- a short string, sufficient to identify the expression
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getStreamerName
Get the (partial) name of a class that supports streaming of this kind of expression- Overrides:
getStreamerName
in classExpression
- Returns:
- the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class
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getElaborator
Make an elaborator for this expression- Overrides:
getElaborator
in classExpression
- Returns:
- a suitable elaborator
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