net.sf.saxon.sort
public class SortExpression extends Expression implements SortKeyEvaluator
Constructor Summary | |
---|---|
SortExpression(Expression select, SortKeyDefinition[] sortKeys)
Create a sort expression |
Method Summary | |
---|---|
PathMap.PathMapNodeSet | addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. |
int | computeCardinality()
Determine the static cardinality |
int | computeSpecialProperties()
Get the static properties of this expression (other than its type). |
Expression | copy()
Copy an expression. |
Item | evaluateSortKey(int n, XPathContext c)
Callback for evaluating the sort keys |
void | explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
Expression | getBaseExpression()
Get the expression defining the sequence being sorted |
ItemType | getItemType(TypeHierarchy th)
Determine the data type of the items returned by the expression, if possible
|
boolean | hasLoopingSubexpression(Expression child)
Given an expression that is an immediate child of this expression, test whether
the evaluation of the parent expression causes the child expression to be
evaluated repeatedly |
boolean | isSortKey(Expression child)
Test whether a given expression is one of the sort keys |
SequenceIterator | iterate(XPathContext context)
Enumerate the results of the expression |
Iterator<Expression> | iterateSameFocusSubExpressions()
Get the immediate sub-expressions of this expression that are evaluated with the
same focus (context item, position, and size) as the parent expression. |
Iterator<Expression> | iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
|
Expression | promote(PromotionOffer offer, Expression parent)
Offer promotion for this subexpression. |
boolean | replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression
|
Expression | simplify(ExpressionVisitor visitor)
Simplify an expression |
Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the expression |
Parameters: select the expression whose result is to be sorted sortKeys the set of sort key definitions to be used, in major to minor order
The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.
Parameters: pathMap the PathMap to which the expression should be added pathMapNodeSet
Returns: the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.
Returns: the copy of the original expression
Returns: the expression whose result is to be sorted
Parameters: th the type hierarchy cache
Returns: a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known in advance)
Parameters: child the immediate subexpression
Returns: true if the child expression is evaluated repeatedly
Parameters: child the given expression
Returns: true if the given expression is one of the sort keys
Returns: an iterator containing those sub-expressions of this expression that are evaluated with the same focus as the parent expression
Returns: an iterator containing the sub-expressions of this expression
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: visitor an expression visitor 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 to ITEM_TYPE
Returns: the original expression, rewritten if appropriate to optimize execution
Throws: XPathException if an error is discovered during this phase (typically a type error)
Parameters: offer 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 parent
Returns: if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
Throws: net.sf.saxon.trans.XPathException if any error is detected
Parameters: original the original subexpression replacement the replacement subexpression
Returns: true if the original subexpression is found
Parameters: visitor an expression visitor