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java.lang.Objectnet.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.SingleNodeExpression
A node set expression that will always return zero or one nodes
| Field Summary |
| Fields inherited from class net.sf.saxon.expr.ComputedExpression |
locationId, staticProperties |
| Fields inherited from interface net.sf.saxon.expr.Expression |
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD |
| Constructor Summary | |
SingleNodeExpression()
|
|
| Method Summary | |
int |
computeCardinality()
Specify that the expression returns a singleton |
int |
computeSpecialProperties()
|
boolean |
effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression. |
Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item. |
int |
getIntrinsicDependencies()
Determine which aspects of the context the expression depends on. |
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the items returned by this expression |
abstract NodeInfo |
getNode(XPathContext context)
Get the single node to which this expression refers. |
SequenceIterator |
iterate(XPathContext context)
Evaluate the expression in a given context to return an iterator |
Expression |
optimize(Optimizer opt,
StaticContext env,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions. |
Expression |
typeCheck(StaticContext env,
ItemType contextItemType)
Type-check the expression. |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Methods inherited from interface net.sf.saxon.expr.Expression |
display |
| Constructor Detail |
public SingleNodeExpression()
| Method Detail |
public Expression typeCheck(StaticContext env,
ItemType contextItemType)
throws XPathException
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
XPathException
public Expression optimize(Optimizer opt,
StaticContext env,
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.
opt - the optimizer in use. This provides access to supporting functions; it also allows
different optimization strategies to be used in different circumstances.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)
XPathExceptionpublic int computeCardinality()
computeCardinality in class ComputedExpressionpublic ItemType getItemType(TypeHierarchy th)
th -
public int getIntrinsicDependencies()
getIntrinsicDependencies in class ComputedExpressionpublic int computeSpecialProperties()
computeSpecialProperties in class ComputedExpression
public abstract NodeInfo getNode(XPathContext context)
throws XPathException
XPathException
public SequenceIterator iterate(XPathContext context)
throws XPathException
iterate in interface Expressioniterate in class ComputedExpressioncontext - the evaluation context
XPathException - if any dynamic error occurs evaluating the
expression
public Item evaluateItem(XPathContext context)
throws XPathException
ComputedExpression
evaluateItem in interface ExpressionevaluateItem in class ComputedExpressioncontext - The context in which the expression is to be evaluated
XPathException - if any dynamic error occurs evaluating the
expression
public boolean effectiveBooleanValue(XPathContext context)
throws XPathException
ComputedExpression
effectiveBooleanValue in interface ExpressioneffectiveBooleanValue in class ComputedExpressioncontext - The context in which the expression is to be evaluated
XPathException - if any dynamic error occurs evaluating the
expression
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