Package net.sf.saxon.expr

Class EquivalenceComparer

java.lang.Object

net.sf.saxon.expr.sort.GenericAtomicComparer

net.sf.saxon.expr.EquivalenceComparer

All Implemented Interfaces:

AtomicComparer

public class EquivalenceComparer
extends GenericAtomicComparer

A comparer that compares atomic values for equality, with the properties: - non-comparable types compare false - NaN compares equal to NaN

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	EquivalenceComparer(StringCollator collator, XPathContext context)

Method Summary

Modifier and Type	Method	Description
boolean	comparesEqual(AtomicValue a, AtomicValue b)	Compare two AtomicValue objects for equality according to the rules for their data type.
EquivalenceComparer	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 net.sf.saxon.expr.sort.GenericAtomicComparer

compareAtomicValues, equals, getCollator, getContext, getStringCollator, hashCode, makeAtomicComparer

Methods inherited from class java.lang.Object

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

Constructor Detail

EquivalenceComparer

protected EquivalenceComparer(StringCollator collator,
                              XPathContext context)

Method Detail

provideContext

public EquivalenceComparer provideContext(XPathContext context)

Description copied from class: GenericAtomicComparer

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

Specified by:

provideContext in interface AtomicComparer

Overrides:

provideContext in class GenericAtomicComparer

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

comparesEqual

public boolean comparesEqual(AtomicValue a,
                             AtomicValue b)
                      throws NoDynamicContextException

Compare two AtomicValue objects for equality 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:

comparesEqual in interface AtomicComparer

Overrides:

comparesEqual in class GenericAtomicComparer

Parameters:

a - the first object to be compared. If it is a StringValue, the collator is used to compare the values, otherwise the value must implement the equals() method.

b - the second object to be compared. This must be comparable with the first object: for example, if one is a string, they must both be strings.

Returns:

true if the values are equal, false if not

Throws:

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

NoDynamicContextException - if no dynamic context has been supplied, and a dynamic context is needed (for example, because the comparison uses the implicit timezone)

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

Overrides:

save in class GenericAtomicComparer

Returns:

a string representation of the AtomicComparer