circular-sclist/at-start [ Methods ]
[ Top ] [ circular-sclist ] [ Methods ]
FUNCTION
Determines whether the pointer for the given circular-sclist object is at the head of its list.
ARGUMENTS
- A circular-sclist object.
RETURN VALUE
EXAMPLE
;; At creation the pointer is located at the start of the list (let ((cscl (make-cscl '(0 1 2 3 4)))) (at-start cscl)) => T ;; Retrieve a number of the items using get-next, then determine whether the ;; pointer is located at the start of the list (let ((cscl (make-cscl '(0 1 2 3 4)))) (loop repeat 7 do (get-next cscl)) (at-start cscl)) => NIL
SYNOPSIS
(defmethod at-start ((cscl circular-sclist))
circular-sclist/get-last [ Methods ]
[ Top ] [ circular-sclist ] [ Methods ]
FUNCTION
Return the the most recent item retrieved in a circular-sclist object.
ARGUMENTS
- A circular-sclist object.
RETURN VALUE
An item from the given circular-sclist object.
EXAMPLE
;; Retrieves the final item in the list at creation (let ((cscl (make-cscl '(0 1 2 3 4)))) (get-last cscl)) => 4 ;; Get and print a number of items from the list using get-next, then return ;; the most recent item retrieved using get-last (let ((cscl (make-cscl '(0 1 2 3 4)))) (loop repeat 7 do (print (get-next cscl))) (get-last cscl)) => 1
SYNOPSIS
(defmethod get-last ((cscl circular-sclist))
circular-sclist/get-next [ Methods ]
[ Top ] [ circular-sclist ] [ Methods ]
FUNCTION
Get the next item in a given circular-sclist object. The class automatically keeps track of the last item retrieved. If the final item of the given circular-sclist object was the last item retrieved, the method begins again at the beginning of the list.
ARGUMENTS
- A circular-sclist object.
RETURN VALUE
An item from the given circular-sclist object.
EXAMPLE
;; Repeatedly calling get-next retrieves each subsequent item from the ;; given circular-sclist object. When the list has been exhausted, retrieval ;; begins again from the head of the list. (let ((cscl (make-cscl '(0 1 2 3 4)))) (loop repeat 10 do (print (get-next cscl)))) => 0 1 2 3 4 0 1 2 3 4
SYNOPSIS
(defmethod get-next ((cscl circular-sclist))
circular-sclist/make-cscl [ Functions ]
[ Top ] [ circular-sclist ] [ Functions ]
FUNCTION
Create a circular-sclist object from a specified list of items. The items themselves may also be lists.
ARGUMENTS
- A list.
OPTIONAL ARGUMENTS
- keyword argument :id. A symbol that will be used as the ID for the created circular-sclist object. Default = NIL. - keyword argument :bounds-alert. T or NIL to indicate whether or not to print a warning if when an attempt is made to access the object using an out-of-bounds index number (i.e., not enough elements in the list). T = print a warning. Default = T. - keyword argument :copy. T or NIL to indicate whether the given data list should be copied (any slippery-chicken class instances will be cloned), with subsequent modifications being applied to the copy. T = copy. Default = T.
RETURN VALUE
A circular-sclist object.
EXAMPLE
;; Returns a circular-sclist object with ID of NIL, bounds-alert=T and copy=T ;; by default (make-cscl '(1 2 3 4)) => CIRCULAR-SCLIST: current 0 SCLIST: sclist-length: 4, bounds-alert: T, copy: T LINKED-NAMED-OBJECT: previous: NIL, this: NIL, next: NIL NAMED-OBJECT: id: NIL, tag: NIL, data: (1 2 3 4) ;; Can be created using nested lists (let ((cscl (make-cscl '((1 (4 5 6)) (2 (7 8 9)) (3 (10 11 12)))))) (data cscl)) => ((1 (4 5 6)) (2 (7 8 9)) (3 (10 11 12))) ;; Setting the ID (make-cscl '(1 2 3 4) :id 'test-cscl) => CIRCULAR-SCLIST: current 0 SCLIST: sclist-length: 4, bounds-alert: T, copy: T LINKED-NAMED-OBJECT: previous: NIL, this: NIL, next: NIL NAMED-OBJECT: id: TEST-CSCL, tag: NIL, data: (1 2 3 4) ;; By default, attempts to access the object with an out-of-bounds index result ;; in a warning being printed (let ((cscl (make-cscl '(1 2 3 4)))) (get-nth 11 cscl)) => NIL WARNING: sclist::sclist-check-bounds: Illegal list reference: 11 (length = 4) (sclist id = NIL) ;; This can be suppressed by creating the object with :bounds-alert set to NIL (let ((cscl (make-cscl '(1 2 3 4) :bounds-alert nil))) (get-nth 11 cscl)) => NIL
SYNOPSIS
(defun make-cscl (list &key (id nil) (bounds-alert t) (copy t))
circular-sclist/reset [ Methods ]
[ Top ] [ circular-sclist ] [ Methods ]
FUNCTION
Reset the pointer of a given circular-sclist object. The pointer is reset to 0 by default, but the desired index may be specified using the optional argument. NB: An immediately subsequent get-next call will retrieve the item at the index to which the pointer is reset. An immediately subsequent get-last call will retrieve the item at the index one-less than the value to which the pointer is set.
ARGUMENTS
- A circular-sclist object.
OPTIONAL ARGUMENTS
- An index integer to which the pointer for the given circular-sclist object should be reset.
RETURN VALUE
Returns T.
EXAMPLE
;; Resets to 0 by default. Here: Get a number of items using get-next, reset ;; the pointer, and apply get-next again. (let ((cscl (make-cscl '(0 1 2 3 4)))) (loop repeat 8 do (print (get-next cscl))) (reset cscl) (get-next cscl)) => 0 ;; Reset to a specified index (let ((cscl (make-cscl '(0 1 2 3 4)))) (loop repeat 8 do (print (get-next cscl))) (reset cscl 3) (get-next cscl)) => 3 ;; By default, get-last will then retrieve the item at index one less than the ;; reset value (let ((cscl (make-cscl '(0 1 2 3 4)))) (loop repeat 8 do (print (get-next cscl))) (reset cscl 3) (get-last cscl)) => 2
SYNOPSIS
(defmethod reset ((cscl circular-sclist) &optional where)
sclist/circular-sclist [ Classes ]
[ Top ] [ sclist ] [ Classes ]
NAME
circular-sclist File: circular-sclist.lsp Class Hierarchy: named-object -> linked-named-object -> sclist -> circular-sclist Version: 1.0.0-beta1 Project: slippery chicken (algorithmic composition) Purpose: Implementation of the circular-sclist class which offers the use of a function to cycle through the values in the sclist, starting at the beginning again once we've reached the end. Author: Michael Edwards: m@michael-edwards.org Creation date: February 19th 2001 $$ Last modified: 21:25:56 Mon May 14 2012 BST SVN ID: $Id: circular-sclist.lsp 1764 2012-05-17 11:49:59Z medward2 $