Package net.sf.saxon.expr.sort
Class NumericComparer
- java.lang.Object
-
- net.sf.saxon.expr.sort.NumericComparer
-
- All Implemented Interfaces:
AtomicComparer
- Direct Known Subclasses:
NumericComparer11
public class NumericComparer extends java.lang.Object implements AtomicComparer
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.
-
-
Field Summary
Fields Modifier and Type Field Description protected StringToDoubleconverter
-
Constructor Summary
Constructors Modifier Constructor Description protectedNumericComparer()
-
Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description intcompareAtomicValues(AtomicValue a, AtomicValue b)Compare two Items by converting them to numbers and comparing the numeric values.booleancomparesEqual(AtomicValue a, AtomicValue b)Compare two AtomicValue objects for equality according to the rules for their data type.StringCollatorgetCollator()Get the collation used by this AtomicComparer if anystatic NumericComparergetInstance()AtomicComparerprovideContext(XPathContext context)Supply the dynamic context in case this is needed for the comparisonjava.lang.Stringsave()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
-
-
-
Field Detail
-
converter
protected StringToDouble converter
-
-
Method Detail
-
getInstance
public static NumericComparer getInstance()
-
getCollator
public StringCollator getCollator()
Description copied from interface:AtomicComparerGet the collation used by this AtomicComparer if any- Specified by:
getCollatorin interfaceAtomicComparer- Returns:
- the collation used for comparing strings, or null if not applicable
-
provideContext
public AtomicComparer provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison- Specified by:
provideContextin 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
-
compareAtomicValues
public int compareAtomicValues(AtomicValue a, AtomicValue b)
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:
compareAtomicValuesin interfaceAtomicComparer- Parameters:
a- the first Item to be compared.b- the second Item to be compared.- Returns:
- <0 if a<b, 0 if a=b, >0 if a>b
- Throws:
java.lang.ClassCastException- if the objects are not Items
-
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:
comparesEqualin 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:
java.lang.ClassCastException- if the objects are not comparable
-
save
public java.lang.String 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:
savein interfaceAtomicComparer- Returns:
- a string representation of the AtomicComparer
-
-