Package net.sf.saxon.expr.sort
Class DoubleSortComparer
java.lang.Object
net.sf.saxon.expr.sort.DoubleSortComparer
- All Implemented Interfaces:
AtomicComparer
An AtomicComparer used for sorting values that are known to be numeric.
It also supports a separate method for getting a collation key to test equality of items.
This comparator treats NaN values as equal to each other, and less than any other value.
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Method Summary
Modifier and TypeMethodDescriptionint
Compare two AtomicValue objects according to the rules for their data type.boolean
Test whether two values compare equal.Get the collation used by this AtomicComparer if anystatic DoubleSortComparer
Get the singular instance of this classprovideContext
(XPathContext context) Supply the dynamic context in case this is needed for the comparisonsave()
Create a string representation of this AtomicComparer that can be saved in a compiled package and used to reconstitute the AtomicComparer when the package is reloaded
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Method Details
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getInstance
Get the singular instance of this class- Returns:
- the singular instance
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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 AtomicValue objects according to the rules for their data type.- Specified by:
compareAtomicValues
in interfaceAtomicComparer
- Parameters:
a
- the first object to be compared. It is intended that this should normally 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 a<b, 0 if a=b, >0 if a>b
- Throws:
ClassCastException
- if the objects are not comparable
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comparesEqual
Test whether two values compare equal. Note that for this comparer, NaN is considered equal to itself- 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
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save
Create a string representation of this AtomicComparer that can be saved in a compiled package and used to reconstitute the AtomicComparer when the package is reloaded- Specified by:
save
in interfaceAtomicComparer
- Returns:
- a string representation of the AtomicComparer
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