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java.lang.Object
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+--net.sf.saxon.expr.ComputedExpression
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+--net.sf.saxon.expr.Assignation
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+--net.sf.saxon.expr.LetExpression
A LetExpression is modelled on the XQuery syntax let $x := expr return expr. This syntax is not available in the surface XPath language, but it is used internally in an optimized expression tree.
| Field Summary |
| Fields inherited from class net.sf.saxon.expr.Assignation |
action, declaration, nameCode, sequence, slotNumber, variableName |
| 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 | |
LetExpression()
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| Method Summary | |
Expression |
analyze(StaticContext env,
ItemType contextItemType)
Type-check the expression |
int |
computeCardinality()
Determine the static cardinality of the expression |
int |
computeSpecialProperties()
Get the static properties of this expression (other than its type). |
void |
display(int level,
NamePool pool,
java.io.PrintStream out)
Diagnostic print of expression structure |
protected Value |
eval(XPathContext context)
Evaluate the variable. |
Item |
evaluateItem(XPathContext context)
Evaluate the expression as a singleton |
ItemType |
getItemType()
Determine the data type of the items returned by the expression, if possible |
SequenceIterator |
iterate(XPathContext context)
Iterate over the sequence of values |
boolean |
markTailFunctionCalls()
Mark tail function calls |
void |
process(XPathContext context)
Process this expression as an instruction, writing results to the current outputter |
Expression |
promote(PromotionOffer offer)
Promote this expression if possible |
| Methods inherited from class net.sf.saxon.expr.Assignation |
evaluateVariable, getVariableFingerprint, getVariableName, getVariableNameCode, iterateSubExpressions, setAction, setSequence, setSlotNumber, setVariableDeclaration, simplify |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
public LetExpression()
| Method Detail |
public Expression analyze(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 SequenceIterator iterate(XPathContext context)
throws XPathException
iterate in interface Expressioniterate in class ComputedExpressioncontext - supplies the context for evaluation
XPathException - if any dynamic error occurs evaluating the
expression
protected Value eval(XPathContext context)
throws XPathException
XPathException
public Item evaluateItem(XPathContext context)
throws XPathException
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 void process(XPathContext context)
throws XPathException
process in interface Expressionprocess in class ComputedExpressioncontext - The dynamic context, giving access to the current node,
the current variables, etc.
XPathExceptionpublic ItemType getItemType()
public int computeCardinality()
computeCardinality in class ComputedExpressionpublic int computeSpecialProperties()
computeSpecialProperties in class ComputedExpressionpublic boolean markTailFunctionCalls()
markTailFunctionCalls in class ComputedExpression
public Expression promote(PromotionOffer offer)
throws XPathException
promote in interface Expressionpromote in class Assignationoffer - details of the offer, for example the offer to move
expressions that don't depend on the context to an outer level in
the containing expression
XPathException - if any error is detected
public void display(int level,
NamePool pool,
java.io.PrintStream out)
level - indentation level for this expressionpool - NamePool used to expand any names appearing in the expressionout - Output destination
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