net.sf.saxon.expr.sort

Class SimpleTypeComparison

java.lang.Object

net.sf.saxon.expr.sort.SimpleTypeComparison

All Implemented Interfaces:

EqualityMatcher<AtomicSequence>

Direct Known Subclasses:

SimpleTypeIdentityComparison

public class SimpleTypeComparison
extends java.lang.Object
implements EqualityMatcher<AtomicSequence>

This class implements equality and ordering comparisons between values of simple types: that is, atomic values, and sequences of atomic values, following the XSD-defined rules for equality and ordering comparisons. These are not always the same as the XPath-defined rules. In particular, under XSD rules values are generally only comparable with others of the same primitive type; a double and a float, for example, never compare equal.

For ordered data types, the compare() functions follow the usual convention: the return value is -1, 0, or +1 according as the first value is less than, equal to, or greater than the second. For non-ordered data types, if the values are not equal then the functions return SequenceTool.INDETERMINATE_ORDERING.

The class can be used directly to perform comparison between atomic values and sequences. It can also be used to parameterise a CustomSet or CustomMap, to provide a set or map that uses explicit equals() logic rather than relying on the equals() and hashCode() methods of the supplied objects - thus avoiding the need to create wrapper objects purely to redefine equality semantics.

The class is a singleton that cannot be externally instantiated.

Constructor Summary

Constructors

Constructor and Description
SimpleTypeComparison()

Method Summary

Modifier and Type	Method and Description
int	compareItems(AtomicValue a1, AtomicValue a2)
int	compareSequences(AtomicSequence a1, AtomicSequence a2)
boolean	equal(AtomicSequence a, AtomicSequence b) Compare two objects for equality
boolean	equalOrIdentical(AtomicSequence a1, AtomicSequence a2)
static SimpleTypeComparison	getInstance() Get the singleton instance of the class
int	hash(AtomicSequence a) Compute a hash code for an object

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SimpleTypeComparison

public SimpleTypeComparison()

Method Detail

getInstance

public static SimpleTypeComparison getInstance()

Get the singleton instance of the class

Returns:

the singleton instance

compareSequences

public int compareSequences(AtomicSequence a1,
                            AtomicSequence a2)

compareItems

public int compareItems(AtomicValue a1,
                        AtomicValue a2)

equal

public boolean equal(AtomicSequence a,
                     AtomicSequence b)

Description copied from interface: EqualityMatcher

Compare two objects for equality

Specified by:

equal in interface EqualityMatcher<AtomicSequence>

Parameters:

a - one object

b - another object

Returns:

true if the two objects are deemed equal

hash

public int hash(AtomicSequence a)

Description copied from interface: EqualityMatcher

Compute a hash code for an object

Specified by:

hash in interface EqualityMatcher<AtomicSequence>

Parameters:

a - an object

Returns:

a hash code, which has the property that if two objects are equal, then they must have the same hash code

equalOrIdentical

public boolean equalOrIdentical(AtomicSequence a1,
                                AtomicSequence a2)