| java.lang.Object
 net.sf.saxon.expr.ComputedExpression
net.sf.saxon.sort.SortExpression
| SortExpression | | public class SortExpression extends ComputedExpression (Code) | | Expression equivalent to the imaginary syntax
expr sortby (sort-key)+
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| computeCardinality | | public int computeCardinality()(Code) | | Determine the static cardinality
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| computeSpecialProperties | | public int computeSpecialProperties()(Code) | | Get the static properties of this expression (other than its type). The result is
bit-significant. These properties are used for optimizations. In general, if
property bit is set, it is true, but if it is unset, the value is unknown.
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| getItemType | | public ItemType getItemType(TypeHierarchy th)(Code) | | Determine the data type of the items returned by the expression, if possible
a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE,or Type.ITEM (meaning not known in advance)
Parameters:
th - |
| isSortKey | | public boolean isSortKey(Expression child)(Code) | | Test whether a given expression is one of the sort keys
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| iterateSubExpressions | | public Iterator iterateSubExpressions()(Code) | | Get the immediate sub-expressions of this expression. Default implementation
returns a zero-length array, appropriate for an expression that has no
sub-expressions.
an iterator containing the sub-expressions of this expression |
| optimize | | public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException(Code) | | Perform optimisation of an expression and its subexpressions.
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.
Parameters:
opt - the optimizer in use. This provides access to supporting functions; it also allowsdifferent optimization strategies to be used in different circumstances.
Parameters:
env - the static context of the expression
Parameters:
contextItemType - 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 tonet.sf.saxon.type.Type.ITEM_TYPE the original expression, rewritten if appropriate to optimize execution
throws:
net.sf.saxon.trans.StaticError - if an error is discovered during this phase(typically a type error) |
| promote | | public Expression promote(PromotionOffer offer) throws XPathException(Code) | | Offer promotion for this subexpression. The offer will be accepted if the subexpression
is not dependent on the factors (e.g. the context item) identified in the PromotionOffer.
By default the offer is not accepted - this is appropriate in the case of simple expressions
such as constant values and variable references where promotion would give no performance
advantage. This method is always called at compile time.
Parameters:
offer - details of the offer, for example the offer to moveexpressions that don't depend on the context to an outer level inthe containing expression if the offer is not accepted, return this expression unchanged.Otherwise return the result of rewriting the expression to promotethis subexpression
throws:
net.sf.saxon.trans.XPathException - if any error is detected |
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