public final class SingletonAtomizer extends UnaryExpression
operand
locationId, staticProperties
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
Constructor and Description |
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SingletonAtomizer(Expression sequence,
RoleLocator role,
boolean allowEmpty)
Constructor
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Modifier and Type | Method and Description |
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int |
computeCardinality()
Determine the static cardinality of the expression
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int |
computeSpecialProperties()
Determine the special properties of this expression
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protected java.lang.String |
displayOperator(Configuration config)
Give a string representation of the operator for use in diagnostics
|
Item |
evaluateItem(XPathContext context)
Evaluate as an Item.
|
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the items returned by the expression, if possible
|
RoleLocator |
getRole()
Get the RoleLocator (used to construct error messages)
|
Expression |
simplify(StaticContext env)
Simplify an expression
|
Expression |
typeCheck(StaticContext env,
ItemType contextItemType)
Type-check the expression
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display, equals, getBaseExpression, hashCode, iterateSubExpressions, optimize, promote, replaceSubExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
public SingletonAtomizer(Expression sequence, RoleLocator role, boolean allowEmpty)
sequence
- the sequence to be atomizedallowEmpty
- true if the result sequence is allowed to be empty.public Expression simplify(StaticContext env) throws XPathException
simplify
in interface Expression
simplify
in class UnaryExpression
env
- the static contextXPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
typeCheck
in interface Expression
typeCheck
in class UnaryExpression
env
- the static context of the expressioncontextItemType
- 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
StaticError
- if an error is discovered during this phase
(typically a type error)XPathException
public int computeSpecialProperties()
computeSpecialProperties
in class UnaryExpression
StaticProperty.NON_CREATIVE
.public RoleLocator getRole()
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in interface Expression
evaluateItem
in class ComputedExpression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic ItemType getItemType(TypeHierarchy th)
getItemType
in interface Expression
getItemType
in class UnaryExpression
th
- public int computeCardinality()
computeCardinality
in class UnaryExpression
protected java.lang.String displayOperator(Configuration config)
displayOperator
in class UnaryExpression
config
-