net.sf.saxon.sort
Class AtomicSortComparer

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

All Implemented Interfaces:

java.util.Comparator, java.io.Serializable

public class AtomicSortComparer

extends java.lang.Object

implements java.util.Comparator, java.io.Serializable

A Comparator used for comparing atomic values of arbitrary item types. It encapsulates a Collator that is used when the values to be compared are strings. It also supports a separate method for testing equality of items, which can be used for data types that are not ordered. The AtomicSortComparer is identical to the AtomicComparer except for its handling of NaN: it treats NaN values as lower (or higher, at user option) than any other value, and as equal to each other.

See Also:

Serialized Form

Nested Class Summary

static class

AtomicSortComparer.ComparisonKey Inner class: an object used as a comparison key.

Constructor Summary

AtomicSortComparer(java.util.Comparator collator, XPathContext conversion)

Method Summary

int	compare(java.lang.Object a, java.lang.Object b) Compare two AtomicValue objects according to the rules for their data type.
AtomicSortComparer.ComparisonKey	getComparisonKey(AtomicValue a) Get a comparison key for an object.
void	setEmptyLeast(boolean least) Indicate whether NaN should be sorted before or after other float/double values.

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

AtomicSortComparer

public AtomicSortComparer(java.util.Comparator collator,
                          XPathContext conversion)

Method Detail

setEmptyLeast

public void setEmptyLeast(boolean least)

Indicate whether NaN should be sorted before or after other float/double values. By default NaN comes first.

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 java.util.Comparator

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

getComparisonKey

public AtomicSortComparer.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.