com.icl.saxon.expr
Class SortedSelection

java.lang.Object
  extended bycom.icl.saxon.expr.Expression
      extended bycom.icl.saxon.expr.NodeSetExpression
          extended bycom.icl.saxon.expr.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
evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getDataType, outputStringValue, selectFirst
 
Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsNumber, getStaticContext, indent, isContextDocumentNodeSet, make, setStaticContext, usesCurrent
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

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

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:
java.lang.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()
                    throws XPathException
Simplify an expression

Overrides:
simplify in class Expression
Returns:
the simplified expression
Throws:
XPathException

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

Specified by:
getDependencies in class 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.

Specified by:
reduce in class 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
Throws:
XPathException

enumerate

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

Specified by:
enumerate in class NodeSetExpression
Parameters:
context - The context for the evaluation
sort - True if the nodes must be returned in document order
Returns:
the sorted nodeset
Throws:
XPathException

display

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

Specified by:
display in class Expression