net.sf.saxon.sort

Class TextComparer

public class TextComparer extends Object implements AtomicComparer, Serializable

A Comparer used for comparing sort keys when data-type="text". The items to be compared are converted to strings, and the strings are then compared using an underlying collator

Author: Michael H. Kay

Constructor Summary
TextComparer(AtomicComparer baseComparer)
Method Summary
intcompareAtomicValues(AtomicValue a, AtomicValue b)
Compare two Items by converting them to strings and comparing the string values.
booleancomparesEqual(AtomicValue a, AtomicValue b)
Compare two AtomicValue objects for equality according to the rules for their data type.
AtomicComparergetBaseComparer()
Get the underlying comparer (which doesn't do conversion to string)
ComparisonKeygetComparisonKey(AtomicValue a)
Get a comparison key for an object.
AtomicComparerprovideContext(XPathContext context)
Supply the dynamic context in case this is needed for the comparison

Constructor Detail

TextComparer

public TextComparer(AtomicComparer baseComparer)

Method Detail

compareAtomicValues

public int compareAtomicValues(AtomicValue a, AtomicValue b)
Compare two Items by converting them to strings and comparing the string values.

Parameters: a the first Item to be compared. b the second Item to be compared.

Returns: <0 if a0 if a>b

Throws: ClassCastException if the objects are not Items, or are items that cannot be convered to strings (e.g. QNames)

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.

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: ClassCastException if the objects are not comparable

getBaseComparer

public AtomicComparer getBaseComparer()
Get the underlying comparer (which doesn't do conversion to string)

getComparisonKey

public ComparisonKey getComparisonKey(AtomicValue a)
Get a comparison key for an object. This must satisfy the rule that if two objects are equal according to the XPath eq operator, then their comparison keys are equal according to the Java equals() method, and vice versa. There is no requirement that the comparison keys should reflect the ordering of the underlying objects.

provideContext

public 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

Throws: net.sf.saxon.trans.NoDynamicContextException if the context is an "early evaluation" (compile-time) context