Class TextComparer

  • All Implemented Interfaces:
    java.io.Serializable, AtomicComparer

    public class TextComparer
    extends java.lang.Object
    implements AtomicComparer, java.io.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
    See Also:
    Serialized Form
    • Constructor Detail

    • Method Detail

      • getBaseComparer

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

        public StringCollator getCollator()
        Description copied from interface: AtomicComparer
        Get the collation used by this AtomicComparer if any
        Specified by:
        getCollator in interface AtomicComparer
        Returns:
        the collation used for comparing strings, or null if not applicable
      • provideContext

        public AtomicComparer provideContext​(XPathContext context)
        Supply the dynamic context in case this is needed for the comparison
        Specified by:
        provideContext in interface AtomicComparer
        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:
        NoDynamicContextException - if the context is an "early evaluation" (compile-time) context
      • compareAtomicValues

        public int compareAtomicValues​(AtomicValue a,
                                       AtomicValue b)
                                throws java.lang.ClassCastException,
                                       NoDynamicContextException
        Compare two Items by converting them to strings and comparing the string values.
        Specified by:
        compareAtomicValues in interface AtomicComparer
        Parameters:
        a - the first Item to be compared.
        b - the second Item to be compared.
        Returns:
        <0 if a0 if a>b
        Throws:
        java.lang.ClassCastException - if the objects are not Items, or are items that cannot be convered to strings (e.g. QNames)
        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

        public 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.
        Specified by:
        comparesEqual in interface AtomicComparer
        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
      • getComparisonKey

        public ComparisonKey getComparisonKey​(AtomicValue a)
                                       throws NoDynamicContextException
        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.
        Specified by:
        getComparisonKey in interface AtomicComparer
        Throws:
        NoDynamicContextException