net.sf.saxon.sort
Class NumericComparer
java.lang.Object
net.sf.saxon.sort.NumericComparer
- AtomicComparer, Serializable
public class NumericComparer
extends java.lang.Object
A Comparer used for comparing sort keys when data-type="number". The items to be
compared are converted to numbers, and the numbers are then compared directly. NaN values
compare equal to each other, and equal to an empty sequence, but less than anything else.
This class is used in XSLT only, so there is no need to handle XQuery's "empty least" vs
"empty greatest" options.
compareAtomicValues
public int compareAtomicValues(AtomicValue a,
AtomicValue b)
Compare two Items by converting them to numbers and comparing the numeric values. If either
value cannot be converted to a number, it is treated as NaN, and compares less that the other
(two NaN values compare equal).
- compareAtomicValues in interface AtomicComparer
a
- the first Item to be compared.b
- the second Item to be compared.
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.
- comparesEqual in interface AtomicComparer
a
- the first object to be compared.b
- the second object to be compared.
- true if the values are equal, false if not
getComparisonKey
public ComparisonKey getComparisonKey(AtomicValue a)
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