com.icl.saxon.expr

Class SortedSelection

public class SortedSelection extends NodeSetExpression

A NodeSetExpression that retrieves nodes in order according to a specified sort key.
Note there is no direct XSL expression syntax that generates this.
The expression sorts a base NodeSet according to the value of a specified sort key. The sort key may be composite. The base NodeSet will always be in document order.
Constructor Summary
SortedSelection(Expression s, int k)
Constructor
Method Summary
voiddisplay(int level)
Diagnostic print of expression structure
NodeEnumerationenumerate(Context context, boolean sort)
Evaluate the expression by sorting the base nodeset using the supplied key.
intgetDependencies()
Determine which aspects of the context the expression depends on.
Expressionreduce(int dependencies, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
voidsetSortKey(SortKeyDefinition sk, int k)
Add a sort key and other sorting parameters
Expressionsimplify()
Simplify an expression

Constructor Detail

SortedSelection

public SortedSelection(Expression s, int k)
Constructor

Parameters: s An expression whose value is the base nodeset to be sorted k the number of sort keys

Method Detail

display

public void display(int level)
Diagnostic print of expression structure

enumerate

public NodeEnumeration enumerate(Context context, boolean sort)
Evaluate the expression by sorting the base nodeset using the supplied key.

Parameters: context The context for the evaluation sort: must be false (because document order would be meaningless)

Returns: the sorted nodeset

getDependencies

public int getDependencies()
Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE

reduce

public Expression reduce(int dependencies, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.

Parameters: dependencies The dependencies to be removed context The context to be used for the partial evaluation

Returns: a new expression that does not have any of the specified dependencies

setSortKey

public void setSortKey(SortKeyDefinition sk, int k)
Add a sort key and other sorting parameters

Parameters: sk A SortKeyDefinition k The index of this SortKeyDefinition. The first sort key in major-to-minor order is numbered 0 (zero), the others are 1, 2, ... in sequence.

Throws: ArrayIndexOutOfBoundsException if the sort key index is out of range, according to the number of sort keys defined when the SortedSelection was initialized.

simplify

public Expression simplify()
Simplify an expression

Returns: the simplified expression