net.sf.saxon.sort
Interface AtomicComparer
- Serializable
- AtomicSortComparer, CalendarValueComparer, CodepointCollatingComparer, CollatingAtomicComparer, ComparableAtomicValueComparer, DecimalSortComparer, DescendingComparer, DoubleSortComparer, EmptyGreatestComparer, EqualityComparer, GenericAtomicComparer, NumericComparer, TextComparer
public interface AtomicComparer
extends Serializable
Interface representing an object that can be used to compare two XPath atomic values for equality or
for ordering.
compareAtomicValues
public int compareAtomicValues(AtomicValue a,
AtomicValue b)
throws NoDynamicContextException
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.
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 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.
NoDynamicContextException
- if this comparer required access to dynamic context information,
notably the implicit timezone, and this information is not available. In general this happens if a
context-dependent comparison is attempted at compile-time, and it signals the compiler to generate
code that tries again at run-time.
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.
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)
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.
provideContext
public AtomicComparer provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison
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