get the protocol more right

[specializable.git] / cons-specializer.lisp

diff --git a/cons-specializer.lisp b/cons-specializer.lisp
index c0ec716a3d51f8c0aeb82aab703836d3aaeffce9..3922a6abd59c09c4f6daf1321fd3f129bd8a621b 100644 (file)
--- a/cons-specializer.lisp
+++ b/cons-specializer.lisp
@@ -21,40 +21,41 @@
   (typecase arg
     ((cons symbol) (car arg))
     (t (call-next-method))))
-;;; FIXME: it looks like these protocol functions should have the GF
-;;; as an argument, since generalizer-of-using-class does
-(defmethod specializer-accepts-generalizer-p ((specializer cons-specializer) thing)
+(defmethod specializer-accepts-generalizer-p ((gf cons-generic-function) (specializer cons-specializer) thing)
   (if (eql (%car specializer) thing)
       (values t t)
       (values nil t)))
-;;; FIXME: yes, definitely need the gf!
-(defmethod specializer-accepts-generalizer-p (specializer (thing symbol))
-  (specializer-accepts-generalizer-p specializer (find-class 'cons)))
+(defmethod specializer-accepts-generalizer-p ((gf cons-generic-function) (specializer sb-mop:specializer) (thing symbol))
+  (specializer-accepts-generalizer-p gf specializer (find-class 'cons)))
 
-;;; this one might not need the GF
+;;; note: this method operates in full knowledge of the object, and so
+;;; does not require the generic function as an argument.
 (defmethod specializer-accepts-p ((specializer cons-specializer) obj)
   (and (consp obj)
        (eql (car obj) (%car specializer))))
-;;; but this one does: it doesn't look like it here, but at issue is
-;;; who is responsible for the SPECIALIZER< method for two distinct
-;;; user-defined specializers.  Also consider a symbol generalizer
-;;; being used to compare two class specializers.
-(defmethod specializer< ((s1 cons-specializer) (s2 cons-specializer) generalizer)
+
+(defmethod specializer< ((gf cons-generic-function) (s1 cons-specializer) (s2 cons-specializer) generalizer)
   (declare (ignore generalizer))
   (if (eql (%car s1) (%car s2))
       '=
       nil))
-(defmethod specializer< ((s1 cons-specializer) (s2 class) generalizer)
+(defmethod specializer< ((gf cons-generic-function) (s1 cons-specializer) (s2 class) generalizer)
   (declare (ignore generalizer))
   '<)
-(defmethod specializer< ((s1 cons-specializer) (s2 sb-mop:eql-specializer) generalizer)
+(defmethod specializer< ((gf cons-generic-function) (s1 cons-specializer) (s2 sb-mop:eql-specializer) generalizer)
   (declare (ignore generalizer))
   '>)
-(defmethod specializer< ((s1 sb-mop:specializer) (s2 cons-specializer) generalizer)
-  (ecase (specializer< s2 s1 generalizer)
+(defmethod specializer< ((gf cons-generic-function) (s1 sb-mop:specializer) (s2 cons-specializer) generalizer)
+  (ecase (specializer< gf s2 s1 generalizer)
     ((<) '>)
     ((>) '<)))
+;;; note: the need for this method is tricky: we need to translate
+;;; from generalizers that our specializers "know" about to those that
+;;; ordinary generic functions and specializers might know about.
+(defmethod specializer< ((gf cons-generic-function) (s1 sb-mop:specializer) (s2 sb-mop:specializer) (generalizer symbol))
+  (specializer< gf s1 s2 (find-class 'cons)))
 \f
+;;; tests / examples
 (eval
  '(progn
    (defgeneric walk (form)
@@ -74,3 +75,22 @@
    (assert (equal (walk '(foo bar)) '(call (flookup foo) (list (lookup bar)))))
    (assert (equal (walk '(quote bar)) 'bar))
    (assert (equal (walk '(let foo bar)) '(with-bindings foo (lookup bar))))))
+
+(eval
+ '(progn
+   (defgeneric multiple-class-specializers (x)
+     (:generic-function-class cons-generic-function)
+     (:method-combination list))
+   (defmethod multiple-class-specializers list ((x t)) 't)
+   (defmethod multiple-class-specializers list ((x cons)) 'cons)
+   (defmethod multiple-class-specializers list ((x (cons foo))) '(cons foo))
+   (defmethod multiple-class-specializers list ((x (cons bar))) '(cons bar))
+   (defmethod multiple-class-specializers list ((x list)) 'list)
+   (defmethod multiple-class-specializers list ((x null)) 'null)
+   (defmethod multiple-class-specializers list ((x (eql nil))) '(eql nil))
+
+   (assert (equal (multiple-class-specializers nil) '((eql nil) null list t)))
+   (assert (equal (multiple-class-specializers t) '(t)))
+   (assert (equal (multiple-class-specializers (cons nil nil)) '(cons list t)))
+   (assert (equal (multiple-class-specializers (cons 'foo nil)) '((cons foo) cons list t)))
+   (assert (equal (multiple-class-specializers (list 'bar nil t 3)) '((cons bar) cons list t)))))