Package net.sf.saxon.expr.sort

Interface AtomicComparer

All Known Implementing Classes:

AtomicSortComparer, CalendarValueComparer, CodepointCollatingComparer, CollatingAtomicComparer, ContextFreeAtomicComparer, DecimalSortComparer, DescendingComparer, DoubleSortComparer, EmptyGreatestComparer, EqualityComparer, GenericAtomicComparer, NumericComparer, NumericComparer11, SwitchCaseComparer, TextComparer, UntypedNumericComparer

public interface AtomicComparer

Interface representing an object that can be used to compare two XPath atomic values for equality or for ordering.

Method Summary

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 any
AtomicComparer	provideContext(XPathContext context)	Supply the dynamic context in case this is needed for the comparison
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

Method Detail

getCollator

StringCollator getCollator()

Get the collation used by this AtomicComparer if any

Returns:

the collation used for comparing strings, or null if not applicable

provideContext

AtomicComparer provideContext(XPathContext context)

Supply the dynamic context in case this is needed for the comparison

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

int compareAtomicValues(AtomicValue a,
                        AtomicValue b)
                 throws NoDynamicContextException

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.

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

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.

comparesEqual

boolean comparesEqual(AtomicValue a,
                      AtomicValue b)
               throws NoDynamicContextException

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.

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

NoDynamicContextException - if no dynamic context has been supplied, and a dynamic context is needed (for example, because the comparison uses the implicit timezone)

save

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

Returns:

a string representation of the AtomicComparer