Package net.sf.saxon.expr.sort

Class GenericAtomicComparer

java.lang.Object
net.sf.saxon.expr.sort.GenericAtomicComparer
All Implemented Interfaces:
AtomicComparer
Direct Known Subclasses:
SwitchCaseComparer
public class GenericAtomicComparer extends Object implements AtomicComparer
An AtomicComparer used for comparing atomic values of arbitrary item types. It encapsulates a Collator that is used when the values to be compared are strings. It also supports a separate method for testing equality of items, which can be used for data types that are not ordered.

  • Constructor Details

    • GenericAtomicComparer

      public GenericAtomicComparer(StringCollator collator, XPathContext conversionContext)
      Create an GenericAtomicComparer
      Parameters:
      collator - the collation to be used
      conversionContext - a context, used when converting untyped atomic values to the target type.

  • Method Details

    • makeAtomicComparer

      public static AtomicComparer makeAtomicComparer(BuiltInAtomicType type0, BuiltInAtomicType type1, StringCollator collator, XPathContext context)
      Factory method to make a GenericAtomicComparer for values of known types
      Parameters:
      type0 - primitive type of the first operand
      type1 - primitive type of the second operand
      collator - the collation to be used, if any. This is supplied as a SimpleCollation object which encapsulated both the collation URI and the collation itself.
      context - the dynamic context
      Returns:
      a GenericAtomicComparer for values of known types

    • makeAtomicComparisonFunction

      public static GenericAtomicComparer.AtomicComparisonFunction makeAtomicComparisonFunction(BuiltInAtomicType type0, BuiltInAtomicType type1, StringCollator collator, int operator, boolean allowRecursion, int version)
      Factory method to make a ComparisonFunction for values of known types
      Parameters:
      type0 - primitive type of the first operand
      type1 - primitive type of the second operand
      collator - the collation to be used, if any. This is supplied as a SimpleCollation object which encapsulated both the collation URI and the collation itself.
      operator - the comparison operator, fpr example Token.FEQ
      allowRecursion - flag to stop infinite recursion (the function recurses if the static types are not known; it then relies on testing the run-time types)
      Returns:
      a comparison function for two atomic values (neither of which may be null)

    • 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 GenericAtomicComparer 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

    • getStringCollator

      public StringCollator getStringCollator()
      Get the underlying string collator
      Returns:
      the string collator

    • compareAtomicValues

      public 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.
      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
      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 as if they were strings; if different semantics are wanted, the conversion must be done by the caller.
      Specified by:
      comparesEqual in interface AtomicComparer
      Parameters:
      a - the first object to be compared. 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.
      Returns:
      true if the values are equal, false if not
      Throws:
      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)

    • getContext

      public XPathContext getContext()

    • 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

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object