Package net.sf.saxon.expr.sort

Class ContextFreeAtomicComparer

java.lang.Object

net.sf.saxon.expr.sort.ContextFreeAtomicComparer

All Implemented Interfaces:

AtomicComparer

public class ContextFreeAtomicComparer
extends java.lang.Object
implements AtomicComparer

A comparer for comparing two "ordinary" atomic values, where the values implement the Comparable interface and the equals() method with the appropriate XPath semantics. This rules out use of collations, conversion of untyped atomic values, and context dependencies such as implicit timezone.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ContextFreeAtomicComparer()

Method Summary

Modifier and Type	Method	Description
int	compareAtomicValues(AtomicValue a, AtomicValue b)	Compare two AtomicValue objects according to the rules for their data type.
boolean	comparesEqual(AtomicValue a, AtomicValue b)	Compare two AtomicValue objects for equality according to the rules for their data type.
StringCollator	getCollator()	Get the collation used by this AtomicComparer if any
static ContextFreeAtomicComparer	getInstance()	Get the singleton instance of this class
AtomicComparer	provideContext(XPathContext context)	Supply the dynamic context in case this is needed for the comparison
java.lang.String	save()	Create a string representation of this AtomicComparer that can be saved in a compiled package and used to reconstitute the AtomicComparer when the package is reloaded

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ContextFreeAtomicComparer

protected ContextFreeAtomicComparer()

Method Detail

getInstance

public static ContextFreeAtomicComparer getInstance()

Get the singleton instance of this class

Returns:

the singleton instance of this class

getCollator

public StringCollator getCollator()

Description copied from interface: AtomicComparer

Get the collation used by this AtomicComparer if any

Specified by:

getCollator in interface AtomicComparer

Returns:

the collation used for comparing strings, or null if not applicable

provideContext

public AtomicComparer provideContext(XPathContext context)

Supply the dynamic context in case this is needed for the comparison

Specified by:

provideContext in interface AtomicComparer

Parameters:

context - the dynamic evaluation context

Returns:

either the original AtomicComparer, or a new AtomicComparer in which the context is known. The original AtomicComparer is not modified

compareAtomicValues

public int compareAtomicValues(AtomicValue a,
                               AtomicValue b)

Compare two AtomicValue objects according to the rules for their data type. UntypedAtomic values are compared as if they were strings; if different semantics are wanted, the conversion must be done by the caller.

Specified by:

compareAtomicValues in interface AtomicComparer

Parameters:

a - the first object to be compared. This must be an AtomicValue and it must implement Comparable with context-free XPath comparison semantics

b - the second object to be compared. This must be an AtomicValue and it must implement Comparable with context-free XPath comparison semantics

Returns:

<0 if a<b, 0 if a=b, >0 if a>b

Throws:

java.lang.ClassCastException - if the objects are not comparable

comparesEqual

public boolean comparesEqual(AtomicValue a,
                             AtomicValue b)

Compare two AtomicValue objects for equality according to the rules for their data type. UntypedAtomic values are compared by converting to the type of the other operand.

Specified by:

comparesEqual in interface AtomicComparer

Parameters:

a - the first object to be compared. This must be an AtomicValue and it must implement equals() with context-free XPath comparison semantics

b - the second object to be compared. This must be an AtomicValue and it must implement equals() with context-free XPath comparison semantics

Returns:

true if the values are equal, false if not

Throws:

java.lang.ClassCastException - if the objects are not comparable

save

public java.lang.String save()

Create a string representation of this AtomicComparer that can be saved in a compiled package and used to reconstitute the AtomicComparer when the package is reloaded

Specified by:

save in interface AtomicComparer

Returns:

a string representation of the AtomicComparer