Package net.sf.saxon.expr.sort

Class EqualityComparer

java.lang.Object
net.sf.saxon.expr.sort.EqualityComparer
All Implemented Interfaces:
AtomicComparer
public class EqualityComparer extends Object implements AtomicComparer
A comparer for comparing two atomic values where (a) equals is defined, and is implemented using the Java equals() method, and (b) ordering is not defined, and results in a dynamic error.

  • Field Details

  • Method Details

    • getInstance

      public static EqualityComparer getInstance()
      Get the singleton instance of this class
      Returns:
      the singleton instance of this class

    • 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

    • compareAtomicValues

      public int compareAtomicValues(AtomicValue a, AtomicValue b)
      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 interface AtomicComparer
      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:
      ClassCastException - if the objects are not comparable

    • 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.
      Specified by:
      comparesEqual in interface AtomicComparer
      Parameters:
      a - the first object to be compared. This must be an AtomicValue and it must implement equals() with context-free XPath comparison semantics
      b - the second object to be compared. This must be an AtomicValue and it must implement equals() with context-free XPath comparison semantics
      Returns:
      true if the values are equal, false if not
      Throws:
      ClassCastException - if the objects are not comparable

    • save

      public 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
      Specified by:
      save in interface AtomicComparer
      Returns:
      a string representation of the AtomicComparer