Package net.sf.saxon.expr.sort
Class NumericComparer
java.lang.Object
net.sf.saxon.expr.sort.NumericComparer
- All Implemented Interfaces:
Serializable
,AtomicComparer
- Direct Known Subclasses:
NumericComparer11
A Comparer used for comparing sort keys when data-type="number". The items to be
compared are converted to numbers, and the numbers are then compared directly. NaN values
compare equal to each other, and equal to an empty sequence, but less than anything else.
This class is used in XSLT only, so there is no need to handle XQuery's "empty least" vs
"empty greatest" options.
- Author:
- Michael H. Kay
- See Also:
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
Compare two Items by converting them to numbers and comparing the numeric values.boolean
Compare two AtomicValue objects for equality according to the rules for their data type.Get the collation used by this AtomicComparer if anyGet a comparison key for an object.static NumericComparer
provideContext
(XPathContext context) Supply the dynamic context in case this is needed for the comparison
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Field Details
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converter
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Constructor Details
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NumericComparer
protected NumericComparer()
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Method Details
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getInstance
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getCollator
Description copied from interface:AtomicComparer
Get the collation used by this AtomicComparer if any- Specified by:
getCollator
in interfaceAtomicComparer
- Returns:
- the collation used for comparing strings, or null if not applicable
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provideContext
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
Compare two Items by converting them to numbers and comparing the numeric values. If either value cannot be converted to a number, it is treated as NaN, and compares less that the other (two NaN values compare equal).- Specified by:
compareAtomicValues
in interfaceAtomicComparer
- Parameters:
a
- the first Item to be compared.b
- the second Item to be compared.- Returns:
- invalid input: '<'0 if ainvalid input: '<'b, 0 if a=b, >0 if a>b
- Throws:
ClassCastException
- if the objects are not Items
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comparesEqual
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.b
- the second object to be compared.- Returns:
- true if the values are equal, false if not
- Throws:
ClassCastException
- if the objects are not comparable
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getComparisonKey
Get a comparison key for an object. This must satisfy the rule that if two objects are equal according to the XPath eq operator, then their comparison keys are equal according to the Java equals() method, 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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