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java.lang.Object net.sf.saxon.expr.sort.DescendingComparer
public class DescendingComparer
A Comparer used for comparing descending keys. This simply returns the inverse of the result delivered by the base comparer.
Constructor Summary | |
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DescendingComparer(AtomicComparer base)
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Method Summary | |
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int |
compareAtomicValues(AtomicValue a,
AtomicValue b)
Compare two objects. |
boolean |
comparesEqual(AtomicValue a,
AtomicValue b)
Compare two AtomicValue objects for equality according to the rules for their data type. |
AtomicComparer |
getBaseComparer()
Get the underlying (ascending) comparer |
StringCollator |
getCollator()
Get the collation used by this AtomicComparer if any |
ComparisonKey |
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 |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public DescendingComparer(AtomicComparer base)
Method Detail |
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public AtomicComparer getBaseComparer()
public StringCollator getCollator()
AtomicComparer
getCollator
in interface AtomicComparer
public AtomicComparer provideContext(XPathContext context)
provideContext
in interface AtomicComparer
context
- the dynamic evaluation context
NoDynamicContextException
- if the context is an "early evaluation" (compile-time) contextpublic int compareAtomicValues(AtomicValue a, AtomicValue b) throws NoDynamicContextException
compareAtomicValues
in interface AtomicComparer
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.
ClassCastException
- if the objects are of the wrong type for this Comparer
NoDynamicContextException
- 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.public boolean comparesEqual(AtomicValue a, AtomicValue b) throws NoDynamicContextException
comparesEqual
in interface AtomicComparer
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.
ClassCastException
- if the objects are not comparable
NoDynamicContextException
public ComparisonKey getComparisonKey(AtomicValue a) throws NoDynamicContextException
getComparisonKey
in interface AtomicComparer
NoDynamicContextException
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