Package net.sf.saxon.expr
Class TailCallLoop
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.UnaryExpression
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- net.sf.saxon.expr.TailCallLoop
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,InstructionInfo
,org.xml.sax.Locator
public final class TailCallLoop extends UnaryExpression
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:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description (package private) UserFunction
containingFunction
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Fields inherited from class net.sf.saxon.expr.UnaryExpression
operand
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Fields inherited from class net.sf.saxon.expr.Expression
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD
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Constructor Summary
Constructors Constructor Description TailCallLoop(UserFunction function)
Constructor - create a TailCallLoop
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Expression
copy()
Copy an expression.Item
evaluateItem(XPathContext context)
Evaluate as an Item.UserFunction
getContainingFunction()
Get the containing functionjava.lang.String
getExpressionName()
Give a string representation of the expression name for use in diagnosticsint
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().ItemType
getItemType(TypeHierarchy th)
Determine the data type of the items returned by the expressionSequenceIterator
iterate(XPathContext context)
Iterate over the sequence of valuesvoid
process(XPathContext context)
Process the function bodyExpression
typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression-
Methods inherited from class net.sf.saxon.expr.UnaryExpression
computeCardinality, computeSpecialProperties, displayOperator, equals, explain, getBaseExpression, hashCode, iterateSubExpressions, optimize, promote, replaceSubExpression, simplify, toString
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Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
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Field Detail
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containingFunction
UserFunction containingFunction
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Constructor Detail
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TailCallLoop
public TailCallLoop(UserFunction function)
Constructor - create a TailCallLoop- Parameters:
function
- the function in which this tail call loop appears
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Method Detail
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getContainingFunction
public UserFunction getContainingFunction()
Get the containing function- Returns:
- the containing function
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType 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
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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iterate
public SequenceIterator iterate(XPathContext context) throws XPathException
Iterate over the sequence of values- 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
public Item evaluateItem(XPathContext context) throws XPathException
Evaluate as an Item.- 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
public void process(XPathContext context) throws XPathException
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
- if a dynamic error occurs
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getItemType
public ItemType getItemType(TypeHierarchy th)
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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getExpressionName
public java.lang.String getExpressionName()
Give a string representation of the expression name for use in diagnostics- Overrides:
getExpressionName
in classExpression
- Returns:
- the expression name, as a string
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