Generic function HAS-PREVIOUS-P
Package:
CL.EXTENSIONS.ENUMERATIONS
Syntax:
has-previous-p enumeration => result
Arguments and Values:
enumeration---a bi-directional enumeration instance
result---a generalized boolean
Description:
The generic function HAS-PREVIOUS-P checks whether the bi-directional enumeration enumeration has another element that precedes the current one in the traversal order. If so it returns a non-NIL result, otherwise, result is NIL.
Examples:
cl-prompt> (defvar ve (enumerate (vector 1 2 3))) VE cl-prompt> (has-previous-p ve) NIL cl-prompt> (next ve) 1 cl-prompt> (has-previous-p ve) T
Affected By:
None.
Exceptional Situations:
HAS-PREVIOUS-P is not defined for non BI-DIRECTIONAL-ENUMERATIONs.
See Also:
ENUMERATION class, NEXT, HAS-NEXT-P, CURRENT, PREVIOUS, NO-SUCH-ELEMENT.
Notes:
None.