Package net.sf.saxon.expr
Class TailCallLoop
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.UnaryExpression
net.sf.saxon.expr.TailCallLoop
- All Implemented Interfaces:
Serializable
,SourceLocator
,LocationProvider
,SaxonLocator
,EvaluableItem
,SequenceIterable
,InstructionInfo
,Locator
A TailCallLoop wraps the body of a function that contains tail-recursive function calls. On completion
of the "real" body of the function it tests whether the function has executed a tail call, and if so,
iterates to evaluate the tail call.
- See Also:
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Field Summary
Fields inherited from class net.sf.saxon.expr.UnaryExpression
operand
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptioncopy()
Copy an expression.protected String
Give a string representation of the expression name for use in diagnosticsevaluateItem
(XPathContext context) Evaluate as an Item.Get the containing functionint
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().Determine the data type of the items returned by the expressioniterate
(XPathContext context) Iterate over the sequence of valuesvoid
process
(XPathContext context) Process the function bodytypeCheck
(ExpressionVisitor visitor, ItemType contextItemType) Type-check the expressionMethods inherited from class net.sf.saxon.expr.UnaryExpression
computeCardinality, computeSpecialProperties, displayOperator, equals, explain, getBaseExpression, hashCode, iterateSubExpressions, optimize, promote, replaceSubExpression, simplify, toString
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, 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, typeError
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Constructor Details
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TailCallLoop
Constructor - create a TailCallLoop- Parameters:
function
- the function in which this tail call loop appears
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Method Details
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getContainingFunction
Get the containing function- Returns:
- the containing function
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException Type-check the expression- Overrides:
typeCheck
in classUnaryExpression
- 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 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)
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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. This implementation provides both iterate() and process() methods natively.- Overrides:
getImplementationMethod
in classExpression
- Returns:
- the implementation method, for example
Expression.ITERATE_METHOD
orExpression.EVALUATE_METHOD
orExpression.PROCESS_METHOD
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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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iterate
Iterate over the sequence of values- Specified by:
iterate
in interfaceSequenceIterable
- Overrides:
iterate
in classExpression
- Parameters:
context
- supplies the context for evaluation- Returns:
- a SequenceIterator that can be used to iterate over the result of the expression
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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evaluateItem
Evaluate as an Item.- Specified by:
evaluateItem
in interfaceEvaluableItem
- 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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process
Process the function body- Overrides:
process
in classExpression
- Parameters:
context
- The dynamic context, giving access to the current node, the current variables, etc.- Throws:
XPathException
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getItemType
Determine the data type of the items returned by the expression- Overrides:
getItemType
in classUnaryExpression
- Parameters:
th
- The type hierarchy cache- Returns:
- the item type of the items in the result sequence, insofar as this is known statically.
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displayExpressionName
Give a string representation of the expression name for use in diagnostics- Overrides:
displayExpressionName
in classUnaryExpression
- Returns:
- the expression name, as a string
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