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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.

Field Summary

Fields inherited from class com.icl.saxon.expr.Expression

staticContext

Constructor Summary

SortedSelection(Expression s, int k)
Constructor

Method Summary

void
display(int level)
Diagnostic print of expression structure
NodeEnumeration
enumerate(Context context, boolean sort)
Evaluate the expression by sorting the base nodeset using the supplied key.
int
getDependencies()
Determine which aspects of the context the expression depends on.
Expression
reduce(int dependencies, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
void
setSortKey(SortKeyDefinition sk, int k)
Add a sort key and other sorting parameters
Expression
simplify()
Simplify an expression

Methods inherited from class com.icl.saxon.expr.NodeSetExpression

enumerate, evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getDataType, outputStringValue, selectFirst

Methods inherited from class com.icl.saxon.expr.Expression

containsReferences, display, enumerate, evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getDataType, getDependencies, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, reduce, setStaticContext, simplify, usesCurrent

Constructor Details

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 Details

display

public void display(int level)
Diagnostic print of expression structure
Overrides:
display in interface Expression

enumerate

public NodeEnumeration enumerate(Context context,
                                 boolean sort)
            throws XPathException
Evaluate the expression by sorting the base nodeset using the supplied key.
Overrides:
enumerate in interface NodeSetExpression

Parameters:
context - The context for the evaluation

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
Overrides:
getDependencies in interface Expression

reduce

public Expression reduce(int dependencies,
                         Context context)
            throws XPathException
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
Overrides:
reduce in interface Expression

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.

simplify

public Expression simplify()
            throws XPathException
Simplify an expression
Overrides:
simplify in interface Expression

Returns:
the simplified expression

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