Package net.sf.saxon.expr.sort
Class CollatingAtomicComparer
- java.lang.Object
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- net.sf.saxon.expr.sort.CollatingAtomicComparer
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- All Implemented Interfaces:
java.io.Serializable
,AtomicComparer
public class CollatingAtomicComparer extends java.lang.Object implements AtomicComparer
An AtomicComparer used for comparing strings, untypedAtomic values, and URIs using a collation. A CollatingAtomicComparer is used when it is known in advance that both operands will be of these types. This enables all conversions and promotions to be bypassed: the string values of both operands are simply extracted and passed to the collator for comparison.- Author:
- Michael H. Kay
- See Also:
- Serialized Form
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Constructor Summary
Constructors Constructor Description CollatingAtomicComparer(StringCollator collator, Platform platform)
Create an GenericAtomicComparer
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Method Summary
All 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 anyComparisonKey
getComparisonKey(AtomicValue a)
Get a comparison key for an object.AtomicComparer
provideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison
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Constructor Detail
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CollatingAtomicComparer
public CollatingAtomicComparer(StringCollator collator, Platform platform)
Create an GenericAtomicComparer- Parameters:
collator
- the collation to be used. If the method is called at compile time, this should be a SimpleCollation so that it can be cloned at run-time.platform
- used to obtain collation keys.
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Method Detail
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getCollator
public StringCollator 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
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. 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 equals() method.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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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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