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java.lang.Object
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+--net.sf.saxon.expr.ComputedExpression
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+--net.sf.saxon.sort.TupleSorter
A TupleSorter is an expression that sorts a stream of tuples. It is used to implement XQuery FLWR expressions.
| 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 | |
TupleSorter(Expression base,
FixedSortKeyDefinition[] keys)
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|
| Method Summary | |
Expression |
analyze(StaticContext env,
ItemType contextItemType)
Perform static analysis and optimisation of an expression and its subexpressions. |
int |
computeCardinality()
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void |
display(int level,
NamePool pool,
java.io.PrintStream out)
Diagnostic print of expression structure. |
boolean |
effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression. |
ItemType |
getItemType()
Determine the data type of the expression, if possible. |
SequenceIterator |
iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence. |
java.util.Iterator |
iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
java.lang.Object |
map(Item item,
XPathContext context,
java.lang.Object info)
Mapping function to map the wrapped objects returned by the SortedTupleIterator into real items. |
Expression |
promote(PromotionOffer offer)
Promote this expression if possible |
Expression |
simplify(StaticContext env)
Simplify an expression. |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
public TupleSorter(Expression base,
FixedSortKeyDefinition[] keys)
| Method Detail |
public Expression simplify(StaticContext env)
throws XPathException
ComputedExpression
simplify in interface Expressionsimplify in class ComputedExpressionXPathException - if an error is discovered during expression
rewriting
public Expression analyze(StaticContext env,
ItemType contextItemType)
throws XPathException
ExpressionThis checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.
analyze in interface Expressionenv - 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
XPathExceptionpublic ItemType getItemType()
ExpressionThis method should always return a result, though it may be the best approximation that is available at the time.
getItemType in interface Expressionpublic int computeCardinality()
computeCardinality in class ComputedExpressionpublic java.util.Iterator iterateSubExpressions()
ComputedExpression
iterateSubExpressions in interface ExpressioniterateSubExpressions in class ComputedExpression
public Expression promote(PromotionOffer offer)
throws XPathException
promote in interface Expressionpromote in class ComputedExpressionoffer - 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 SequenceIterator iterate(XPathContext context)
throws XPathException
ComputedExpression
iterate in interface Expressioniterate in class ComputedExpressioncontext - supplies the context for evaluation
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
public void display(int level,
NamePool pool,
java.io.PrintStream out)
Expression
display in interface Expressionlevel - indentation level for this expressionpool - NamePool used to expand any names appearing in the expressionout - Output destination
public java.lang.Object map(Item item,
XPathContext context,
java.lang.Object info)
throws XPathException
map in interface MappingFunctionitem - The item to be mapped.
If context is supplied, this must be the same as context.currentItem().context - The processing context. This is supplied only for mapping constructs that
set the context node, position, and size. Otherwise it is null.info - Arbitrary information supplied by the creator of the MappingIterator. It must be
read-only and immutable for the duration of the iteration.
XPathException
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