net.sf.saxon.sort
Class CollatingAtomicComparer

java.lang.Object
  net.sf.saxon.sort.CollatingAtomicComparer

All Implemented Interfaces:

AtomicComparer, java.util.Comparator, java.io.Serializable

public class CollatingAtomicComparer

extends java.lang.Object

implements AtomicComparer

An AtomicComparer used for comparing strings, untypedAtomic values, and URIs using a collation. A CollatingAtomicComparer is used when it is known in advance that both operands will be of these types. 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.

See Also:

Serialized Form

Constructor Summary

CollatingAtomicComparer(java.util.Comparator collator, Platform platform)
Create an GenericAtomicComparer

Method Summary

int	compare(java.lang.Object a, java.lang.Object 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.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Constructor Detail

CollatingAtomicComparer

public CollatingAtomicComparer(java.util.Comparator collator,
                               Platform platform)

Create an GenericAtomicComparer

Parameters:

collator - the collation to be used

platform - used to obtain collation keys.

Method Detail

compare

public int compare(java.lang.Object a,
                   java.lang.Object 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:

compare in interface AtomicComparer

Parameters:

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.

Returns:

<0 if a0 if a>b

Throws:

java.lang.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.

Specified by:

comparesEqual in interface AtomicComparer

Parameters:

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 equals() method.

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.

Returns:

<0 if a0 if a>b

Throws:

java.lang.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.

Specified by:

getComparisonKey in interface AtomicComparer