net.sf.saxon.sort
Class DescendingComparer
java.lang.Object
net.sf.saxon.sort.DescendingComparer
- AtomicComparer, Serializable
public class DescendingComparer
extends java.lang.Object
A Comparer used for comparing descending keys. This simply returns the inverse of the result
delivered by the base comparer.
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 by converting to the type of the other operand.
- comparesEqual in interface AtomicComparer
a
- the first object to be compared. It is intended that this should be an instance
of AtomicValue, though this restriction is not enforced. 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.
- true if the values are equal, false if not
getBaseComparer
public AtomicComparer getBaseComparer()
Get the underlying (ascending) comparer
- the underlying (ascending) comparer
getComparisonKey
public ComparisonKey getComparisonKey(AtomicValue a)
throws NoDynamicContextException
Get a comparison key for an object. This must satisfy the rule that if two objects are equal
according to the XPath eq operator, then their comparison keys are equal according to the Java
equals() method, and vice versa. There is no requirement that the
comparison keys should reflect the ordering of the underlying objects.
- getComparisonKey in interface AtomicComparer
provideContext
public AtomicComparer provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison
- provideContext in interface AtomicComparer
context
- the dynamic evaluation context
- either the original AtomicComparer, or a new AtomicComparer in which the context
is known. The original AtomicComparer is not modified