net.sf.saxon.sort
Class DoubleSortComparer
java.lang.Object
net.sf.saxon.sort.DoubleSortComparer
- AtomicComparer, Serializable
public class DoubleSortComparer
extends java.lang.Object
An AtomicComparer used for sorting values that are known to be numeric.
It also supports a separate method for getting a collation key to test equality of items.
This comparator treats NaN values as equal to each other, and less than any other value.
compareAtomicValues
public int compareAtomicValues(AtomicValue a,
AtomicValue b)
Compare two AtomicValue objects according to the rules for their data type.
- compareAtomicValues in interface AtomicComparer
a
- the first object to be compared. It is intended that this should normally 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 java.util.Comparable
interface.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.
getComparisonKey
public ComparisonKey getComparisonKey(AtomicValue a)
Get a comparison key for an object. This must satisfy the rule that if two objects are equal as defined
by the XPath eq operator, then their comparison keys are equal as defined by 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
getInstance
public static DoubleSortComparer getInstance()
Get the singular instance of this class
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