Package net.sf.saxon.expr.sort
Class UntypedNumericComparer
- java.lang.Object
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- net.sf.saxon.expr.sort.UntypedNumericComparer
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- All Implemented Interfaces:
AtomicComparer
public class UntypedNumericComparer extends java.lang.Object implements AtomicComparer
A specialist comparer that implements the rules for comparing an untypedAtomic value (always the first operand) to a numeric value (always the second operand)
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Constructor Summary
Constructors Constructor Description UntypedNumericComparer()
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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.StringCollator
getCollator()
Get the collation used by this AtomicComparer if anyAtomicComparer
provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparisonstatic boolean
quickCompare(StringValue a0, NumericValue a1, int operator, ConversionRules rules)
Optimized routine to compare an untyped atomic value with a numeric value.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
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Method Detail
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quickCompare
public static boolean quickCompare(StringValue a0, NumericValue a1, int operator, ConversionRules rules) throws XPathException
Optimized routine to compare an untyped atomic value with a numeric value. This attempts to deliver a quick answer if the comparison is obviously false, without performing the full string-to-double conversion- Parameters:
a0
- the untypedAtomic comparanda1
- the numeric comparandoperator
- the comparison operator: a singleton operator such as Token.FEQrules
- the conversion rules- Returns:
- the result of the comparison
- Throws:
XPathException
- if the first operand is not convertible to a double
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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 a<b, 0 if a=b, >0 if a>b
- Throws:
java.lang.ClassCastException
- if the objects are not comparable
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getCollator
public StringCollator getCollator()
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
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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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.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
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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:
save
in interfaceAtomicComparer
- Returns:
- a string representation of the AtomicComparer
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