net.sf.saxon.sort
Class CodepointCollatingComparer
java.lang.Object
net.sf.saxon.sort.CodepointCollatingComparer
- AtomicComparer, Serializable
public class CodepointCollatingComparer
extends java.lang.Object
An AtomicComparer used for comparing strings, untypedAtomic values, and URIs using the Unicode codepoint
collation.
A CodepointCollatingComparer is used when it is known in advance that both operands will be of these
types, and when the collation is the unicode codepoint collation.
This enables all conversions and promotions to be bypassed: the string values of both operands
are simply extracted and passed to the collator for comparison.
The difference between using this class and using the underlying CodepointCollator directly is that
the compare() method in this class expects two instances of AtomicValue as its operands, whereas the
underlying class expects two instances of java.lang.String. This class makes use of the extra information
held in the wrapping StringValue object, specifically, the knowledge of whether the string contains
surrogate pairs.
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.
- compareAtomicValues in interface AtomicComparer
a
- the first object to be compared. This must be either be an instance
of AtomicValue, or null to represent an empty sequence. Empty collates before non-empty.b
- the second object to be compared. This must be either be an instance
of AtomicValue, or null to represent an empty sequence.
comparesEqual
public boolean comparesEqual(AtomicValue a,
AtomicValue b)
Compare two AtomicValue objects for equality. The values must be instances of xs:string or a type
derived from xs:string. The method will also handle xs:untypedAtomic and xs:anyURI values.
- comparesEqual in interface AtomicComparer
a
- the first object to be compared.b
- the second object to be compared.
getComparisonKey
public ComparisonKey getComparisonKey(AtomicValue a)
Get a comparison key for an object. This must satisfy the rule that if two objects are equal
under the XPath eq operator, then their comparison keys are equal under the Java equals()
function, 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