public abstract class SingleNodeExpression extends Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
?????? |
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SingleNodeExpression() |
?????? | ????? |
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int |
computeCardinality()
Specify that the expression returns a singleton
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int |
computeSpecialProperties()
Compute the special properties of this expression.
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boolean |
effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression.
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Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item.
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int |
getIntrinsicDependencies()
Determine which aspects of the context the expression depends on.
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ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the items returned by this expression
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abstract NodeInfo |
getNode(XPathContext context)
Get the single node to which this expression refers.
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SequenceIterator |
iterate(XPathContext context)
Evaluate the expression in a given context to return an iterator
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Expression |
optimize(ExpressionVisitor visitor,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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Expression |
typeCheck(ExpressionVisitor visitor,
ItemType contextItemType)
Type-check the expression.
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addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, display, doPromotion, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, iterateSubExpressions, markTailFunctionCalls, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeError
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
typeCheck
??? Expression
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 to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
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.
optimize
??? Expression
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 to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public int computeCardinality()
computeCardinality
??? Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public ItemType getItemType(TypeHierarchy th)
getItemType
??? Expression
th
- the type hierarchy cachepublic int getIntrinsicDependencies()
getIntrinsicDependencies
??? Expression
public int computeSpecialProperties()
Expression
StaticProperty
. The "special" properties are properties
other than cardinality and dependencies, and most of them relate to properties of node sequences, for
example whether the nodes are in document order.computeSpecialProperties
??? Expression
public abstract NodeInfo getNode(XPathContext context) throws XPathException
XPathException
public SequenceIterator iterate(XPathContext context) throws XPathException
iterate
???? SequenceIterable
iterate
??? Expression
context
- the evaluation contextXPathException
- if any dynamic error occurs evaluating the
expressionpublic Item evaluateItem(XPathContext context) throws XPathException
Expression
evaluateItem
???? EvaluableItem
evaluateItem
??? Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic boolean effectiveBooleanValue(XPathContext context) throws XPathException
Expression
effectiveBooleanValue
??? Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expression