;; Superclass Linearization for Dylan' for more detail.
;; http://www.webcom.com/haahr/dylan/linearization-oopsla96.html
+;;; Utilities.
+
+(export 'merge-class-lists)
+(defun merge-class-lists (lists pick)
+ "Merge the LISTS of classes, using PICK to break ties.
+
+ This is a convenience wrapper around the main `merge-lists' function.
+ Given that class linearizations (almost?) always specify a custom
+ tiebreaker function, this isn't a keyword argument. Also, this wrapper
+ provides a standard presentation function so that any errors are presented
+ properly."
+ (merge-lists lists
+ :pick pick
+ :present (lambda (class)
+ (format nil "`~A'" (sod-class-name class)))))
+
;;; Tiebreaker functions.
(defun clos-tiebreaker (candidates so-far)
(when (member candidate (sod-class-direct-superclasses class))
(setf winner candidate))))
(unless winner
- (error "SOD INTERNAL ERROR: Failed to break tie in CLOS."))
+ (error "SOD INTERNAL ERROR: Failed to break tie in CLOS"))
winner))
(defun c3-tiebreaker (candidates cpls)
(dolist (candidate candidates)
(when (member candidate cpl)
(return-from c3-tiebreaker candidate))))
- (error "SOD INTERNAL ERROR: Failed to break tie in C3."))
+ (error "SOD INTERNAL ERROR: Failed to break tie in C3"))
;;; Linearization functions.
(remove-duplicates (cons class
(mappend #'superclasses
direct-supers))))))
- (merge-lists (mapcar (lambda (class)
- (cons class
- (sod-class-direct-superclasses class)))
- (superclasses class))
- :pick #'clos-tiebreaker)))
+ (merge-class-lists
+ (mapcar (lambda (class)
+ (cons class (sod-class-direct-superclasses class)))
+ (superclasses class))
+ #'clos-tiebreaker)))
(export 'dylan-cpl)
(defun dylan-cpl (class)
you're going to lose anyway."
(let ((direct-supers (sod-class-direct-superclasses class)))
- (merge-lists (cons (cons class direct-supers)
- (mapcar #'sod-class-precedence-list direct-supers))
- :pick #'clos-tiebreaker)))
+ (merge-class-lists
+ (cons (cons class direct-supers)
+ (mapcar #'sod-class-precedence-list direct-supers))
+ #'clos-tiebreaker)))
(export 'c3-cpl)
(defun c3-cpl (class)
(let* ((direct-supers (sod-class-direct-superclasses class))
(cpls (mapcar #'sod-class-precedence-list direct-supers)))
- (merge-lists (cons (cons class direct-supers) cpls)
- :pick (lambda (candidates so-far)
+ (merge-class-lists (cons (cons class direct-supers) cpls)
+ (lambda (candidates so-far)
(declare (ignore so-far))
(c3-tiebreaker candidates cpls)))))
precedence order i.e., the direct-superclasses list orderings."
(let ((dfs (flavors-cpl class)))
- (cons class (merge-lists (mapcar #'sod-class-precedence-list
+ (cons class
+ (merge-class-lists (mapcar #'sod-class-precedence-list
(sod-class-direct-superclasses class))
- :pick (lambda (candidates so-far)
- (declare (ignore so-far))
- (dolist (class dfs)
- (when (member class candidates)
- (return class))))))))
+ (lambda (candidates so-far)
+ (declare (ignore so-far))
+ (dolist (class dfs)
+ (when (member class candidates)
+ (return class))))))))
;;; Default function.
(reduce (lambda (best this)
(cond ((funcall order best this) best)
((funcall order this best) this)
- (t (error "Unable to choose best ~A." what))))
+ (t (error "Unable to choose best ~A" what))))
items))
(defmethod guess-metaclass ((class sod-class))
(error "In `~A~, chain-to class `~A' is not a proper superclass"
class chain-link)))
+ ;; Check that the initargs declare compatible types. Duplicate entries,
+ ;; even within a class, are harmless, but at most one initarg in any
+ ;; class should declare a default value.
+ (with-slots (class-precedence-list) class
+ (let ((seen (make-hash-table :test #'equal)))
+ (dolist (super class-precedence-list)
+ (with-slots (initargs) super
+ (dolist (initarg (reverse initargs))
+ (let* ((initarg-name (sod-initarg-name initarg))
+ (initarg-type (sod-initarg-type initarg))
+ (initarg-default (sod-initarg-default initarg))
+ (found (gethash initarg-name seen))
+ (found-type (and found (sod-initarg-type found)))
+ (found-default (and found (sod-initarg-default found)))
+ (found-class (and found (sod-initarg-class found)))
+ (found-location (and found (file-location found))))
+ (with-default-error-location (initarg)
+ (cond ((not found)
+ (setf (gethash initarg-name seen) initarg))
+ ((not (c-type-equal-p initarg-type found-type))
+ (cerror* "Inititalization argument `~A' defined ~
+ with incompatible types: ~
+ ~A in class ~A, and ~
+ ~A in class ~A (at ~A)"
+ initarg-name initarg-type super
+ found-type found-class found-location))
+ ((and initarg-default found-default
+ (eql super found-class))
+ (cerror* "Initialization argument `~A' redefined ~
+ with default value ~
+ (previous definition at ~A)"
+ initarg-name found-location))
+ (initarg-default
+ (setf (gethash initarg-name seen) initarg))))))))))
+
;; Check for circularity in the superclass graph. Since the superclasses
;; should already be acyclic, it suffices to check that our class is not
;; a superclass of any of its own direct superclasses.
~mdw / sod / blobdiff