net.sf.saxon.sort

Class ComparableAtomicValueComparer

public class ComparableAtomicValueComparer extends Object implements AtomicComparer

A comparer for comparing two "ordinary" atomic values, where the values implement the Comparable interface and the equals() method with the appropriate XPath semantics. This rules out use of collations, conversion of untyped atomic values, and context dependencies such as implicit timezone.
Constructor Summary
protected ComparableAtomicValueComparer()
Method Summary
intcompareAtomicValues(AtomicValue a, AtomicValue b)
Compare two AtomicValue objects according to the rules for their data type.
booleancomparesEqual(AtomicValue a, AtomicValue b)
Compare two AtomicValue objects for equality according to the rules for their data type.
ComparisonKeygetComparisonKey(AtomicValue a)
Get a comparison key for an object.
static ComparableAtomicValueComparergetInstance()
Get the singleton instance of this class
AtomicComparerprovideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison

Constructor Detail

ComparableAtomicValueComparer

protected ComparableAtomicValueComparer()

Method Detail

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.

Parameters: a the first object to be compared. This must be an AtomicValue and it must implement Comparable with context-free XPath comparison semantics b the second object to be compared. This must be an AtomicValue and it must implement Comparable with context-free XPath comparison semantics

Returns: <0 if a0 if a>b

Throws: ClassCastException if the objects are not comparable

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.

Parameters: a the first object to be compared. This must be an AtomicValue and it must implement equals() with context-free XPath comparison semantics b the second object to be compared. This must be an AtomicValue and it must implement equals() with context-free XPath comparison semantics

Returns: true if the values are equal, false if not

Throws: ClassCastException if the objects are not comparable

getComparisonKey

public ComparisonKey getComparisonKey(AtomicValue a)
Get a comparison key for an object. This must satisfy the rule that if two objects are equal, then their comparison keys are equal, and vice versa. There is no requirement that the comparison keys should reflect the ordering of the underlying objects.

getInstance

public static ComparableAtomicValueComparer getInstance()
Get the singleton instance of this class

Returns: the singleton instance of this class

provideContext

public AtomicComparer provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison

Parameters: context the dynamic evaluation context

Returns: either the original AtomicComparer, or a new AtomicComparer in which the context is known. The original AtomicComparer is not modified