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:

TokenComparators

Method Summary

Methods

Modifier and Type	Method and 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 Detail

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.