net.sf.saxon.sort
Class GenericAtomicComparer

java.lang.Object
  extended bynet.sf.saxon.sort.GenericAtomicComparer
All Implemented Interfaces:
AtomicComparer, java.util.Comparator, java.io.Serializable

public class GenericAtomicComparer
extends java.lang.Object
implements AtomicComparer, 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.

See Also:
Serialized Form

Constructor Summary
GenericAtomicComparer(java.util.Comparator collator, Configuration config)
           
GenericAtomicComparer(java.util.Comparator collator, XPathContext conversion)
          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.
static AtomicComparer makeAtomicComparer(int type0, int type1, java.util.Comparator collator, Configuration config)
          Factory method to make a GenericAtomicComparer for values of known types
 
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

GenericAtomicComparer

public GenericAtomicComparer(java.util.Comparator collator,
                             XPathContext conversion)
Create an GenericAtomicComparer

Parameters:
collator - the collation to be used
conversion - a context, used when converting untyped atomic values to the target type.

GenericAtomicComparer

public GenericAtomicComparer(java.util.Comparator collator,
                             Configuration config)
Method Detail

makeAtomicComparer

public static AtomicComparer makeAtomicComparer(int type0,
                                                int type1,
                                                java.util.Comparator collator,
                                                Configuration config)
Factory method to make a GenericAtomicComparer for values of known types

Parameters:
type0 - primitive type of the first operand
type1 - primitive type of the second operand
collator - the collation to be used, if any
config - the configuration
Returns:
a GenericAtomicComparer for values of known types

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