net.sf.saxon.sort

Class ComparableAtomicValueComparer

Implemented Interfaces:
AtomicComparer, Serializable
Known Direct Subclasses:
DecimalSortComparer

public class ComparableAtomicValueComparer
extends java.lang.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

ComparableAtomicValueComparer()

Method Summary

int
compareAtomicValues(AtomicValue a, AtomicValue b)
Compare two AtomicValue objects according to the rules for their data type.
boolean
comparesEqual(AtomicValue a, AtomicValue b)
Compare two AtomicValue objects for equality according to the rules for their data type.
ComparisonKey
getComparisonKey(AtomicValue a)
Get a comparison key for an object.
static ComparableAtomicValueComparer
getInstance()
Get the singleton instance of this class
AtomicComparer
provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison

Constructor Details

ComparableAtomicValueComparer

protected ComparableAtomicValueComparer()

Method Details

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.
Specified by:
compareAtomicValues in interface AtomicComparer
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

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.
Specified by:
comparesEqual in interface AtomicComparer
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

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.
Specified by:
getComparisonKey in interface AtomicComparer

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
Specified by:
provideContext in interface AtomicComparer
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