Package net.sf.saxon.expr.sort
Class GenericAtomicComparer
java.lang.Object
net.sf.saxon.expr.sort.GenericAtomicComparer
- All Implemented Interfaces:
Serializable
,AtomicComparer
An AtomicComparer used for comparing atomic values of arbitrary item types. It encapsulates
a Collator that is used when the values to be compared are strings. It also supports
a separate method for testing equality of items, which can be used for data types that
are not ordered.
- Author:
- Michael H. Kay
- See Also:
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Constructor Summary
ConstructorsConstructorDescriptionGenericAtomicComparer
(StringCollator collator, XPathContext conversionContext) Create an GenericAtomicComparer -
Method Summary
Modifier and TypeMethodDescriptionint
Compare two AtomicValue objects according to the rules for their data type.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.Get the underlying string collatorstatic AtomicComparer
makeAtomicComparer
(BuiltInAtomicType type0, BuiltInAtomicType type1, StringCollator collator, XPathContext context) Factory method to make a GenericAtomicComparer for values of known typesprovideContext
(XPathContext context) Supply the dynamic context in case this is needed for the comparison
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Constructor Details
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GenericAtomicComparer
Create an GenericAtomicComparer- Parameters:
collator
- the collation to be usedconversionContext
- a context, used when converting untyped atomic values to the target type.
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Method Details
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makeAtomicComparer
public static AtomicComparer makeAtomicComparer(BuiltInAtomicType type0, BuiltInAtomicType type1, StringCollator collator, XPathContext context) Factory method to make a GenericAtomicComparer for values of known types- Parameters:
type0
- primitive type of the first operandtype1
- primitive type of the second operandcollator
- the collation to be used, if any. This is supplied as a SimpleCollation object which encapsulated both the collation URI and the collation itself.context
- the dynamic context- Returns:
- a GenericAtomicComparer for values of known types
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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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getStringCollator
Get the underlying string collator- Returns:
- the string collator
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compareAtomicValues
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:
- invalid input: '<'0 if a invalid input: '<' b, 0 if a = b, >0 if a > b
- Throws:
ClassCastException
- if the objects are not comparableNoDynamicContextException
- if this comparer required access to dynamic context information, notably the implicit timezone, and this information is not available. In general this happens if a context-dependent comparison is attempted at compile-time, and it signals the compiler to generate code that tries again at run-time.
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comparesEqual
Compare two AtomicValue objects for equality 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:
comparesEqual
in interfaceAtomicComparer
- Parameters:
a
- the first object to be compared. 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:
- invalid input: '<'0 if ainvalid input: '<'b, 0 if a=b, >0 if a>b
- Throws:
ClassCastException
- if the objects are not comparableNoDynamicContextException
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getComparisonKey
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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