Package net.sf.saxon.sort
Class EqualityComparer
- java.lang.Object
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- net.sf.saxon.sort.EqualityComparer
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- All Implemented Interfaces:
java.io.Serializable
,AtomicComparer
public class EqualityComparer extends java.lang.Object implements AtomicComparer
A comparer for comparing two atomic values where (a) equals is defined, and is implemented using the Java equals() method, and (b) ordering is not defined, and results in a dynamic error.- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description static EqualityComparer
THE_INSTANCE
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description 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 EqualityComparer
getInstance()
Get the singleton instance of this classAtomicComparer
provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison
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Field Detail
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THE_INSTANCE
public static EqualityComparer THE_INSTANCE
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Method Detail
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getInstance
public static EqualityComparer getInstance()
Get the singleton instance of this class- Returns:
- the singleton instance of this class
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provideContext
public AtomicComparer provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison- Specified by:
provideContext
in interfaceAtomicComparer
- 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
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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 interfaceAtomicComparer
- 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
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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 interfaceAtomicComparer
- Parameters:
a
- the first object to be compared. This must be an AtomicValue and it must implement equals() with context-free XPath comparison semanticsb
- 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
- Throws:
java.lang.ClassCastException
- if the objects are not comparable
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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 interfaceAtomicComparer
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