Module datarush.library
Package com.pervasive.datarush.tokens

Interface TokenComparator

public interface TokenComparator
An object for comparing tokens of compatible types. While the interface is generically typed, using TokenValued, implementations are type specific, working on only tokens of one type (or, in the case of the number types, any number type).
See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    compare()
    Indicates the relative ordering of two token values.
    boolean
    equal()
    Indicates whether the currently bound values are equal.
    TokenOrder
    getDirection()
    Gets the direction of the comparator's ordering.
    TokenType
    getType()
    Gets the type of tokens for which the comparator is valid.
    void
    setLeftSource(TokenValued source)
    Binds the left-hand value of the comparator to the specified object.
    void
    setRightSource(TokenValued source)
    Binds the right-hand value of the comparator to the specified object.

  • Method Details

    • getType

      TokenType getType()
      Gets the type of tokens for which the comparator is valid.
      Returns:
      the valid token type for the comparator

    • getDirection

      TokenOrder getDirection()
      Gets the direction of the comparator's ordering.
      Returns:
      the ordering direction

    • setLeftSource

      void setLeftSource(TokenValued source)
      Binds the left-hand value of the comparator to the specified object. Comparisons will be done using the value of the object at the time of the comparison.
      Parameters:
      source - the value container to use on the left side of comparisons

    • setRightSource

      void setRightSource(TokenValued source)
      Binds the right-hand value of the comparator to the specified object. Comparisons will be done using the value of the object at the time of the comparison.
      Parameters:
      source - the value container to use on the right side of comparisons

    • equal

      boolean equal()
      Indicates whether the currently bound values are equal. Two values are equal if and only if the following are true:
      • neither value is null valued
      • the contained values are equal (according to the rules of the underlying type)
      This logic is consistent with the behavior of SQL null values.
      Returns:
      true if the bound values are equal, false otherwise.

    • compare

      int compare()
      Indicates the relative ordering of two token values. The ordering is interpreted under the direction associated with the comparator. Thus a descending comparator would place "banana" before "apple", an inversion of the natural (ascending) ordering.

      Null valued tokens always compare equal under this method. Note that this disagrees with the behavior of equal().

      Returns:
      a negative integer, zero, or a positive integer if the bound value for the left is respectively before, equivalent to, or after the bound value for the right.