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(in-package #:mulk.protocols)
(defvar *protocols* (make-hash-table))
(defun find-protocol (name &optional (errorp t))
(let ((protocol (gethash name *protocols* nil)))
(when (and errorp (null protocol))
(error "There is no protocol named ~A." name))
protocol))
(defun (setf find-protocol) (protocol name &optional errorp)
(declare (ignore errorp))
(setf (gethash name *protocols*) protocol))
(defun conforms-to-p (class protocol)
(let ((real-class (typecase class
(symbol (find-class class))
(t class)))
(real-protocol (typecase protocol
(symbol (find-protocol protocol))
(t protocol))))
(or (%conforms-to-p real-class real-protocol)
(some #'(lambda (superclass)
(conforms-to-p superclass real-protocol))
(class-direct-superclasses real-class)))))
(defun really-conforms-to-p (class protocol)
(let ((real-class (typecase class
(symbol (find-class class))
(t class)))
(real-protocol (typecase protocol
(symbol (find-protocol protocol))
(t protocol))))
(or (%really-conforms-to-p real-class real-protocol)
(some #'(lambda (superclass)
(really-conforms-to-p superclass real-protocol))
(class-direct-superclasses real-class)))))
(defgeneric %conforms-to-p (class protocol))
(defmethod %conforms-to-p ((class t) (protocol t))
(declare (ignore class protocol))
nil)
(defgeneric %really-conforms-to-p (class protocol))
(defmethod %really-conforms-to-p ((class t) (protocol t))
(declare (ignore class protocol))
nil)
(defclass protocol ()
((name :initarg :name
:reader protocol-name)
(superprotocols :initarg :superprotocols
:reader protocol-superprotocols)
(methods :initarg :methods
:reader protocol-methods)
(options :initarg :options
:reader protocol-options)))
(defmacro define-protocol (name superprotocols methods &rest options)
"Define a new protocol.
superprotocols ::= (*name*\\*)
methods ::= ((method-name [\\* | class-name]\\*)\\*)"
`(progn
(when (find-protocol ',name nil)
(warn (make-condition 'simple-style-warning
:format-control "Redefining protocol ~A."
:format-arguments (list ',name))))
(setf (find-protocol ',name)
(make-instance 'protocol
:name ',name
:superprotocols (mapcar #'find-protocol ',superprotocols)
:methods ',methods
:options ',options))))
(defmethod print-object ((protocol protocol) stream)
(print-unreadable-object (protocol stream)
(format stream "PROTOCOL ~A" (protocol-name protocol))))
(defun ensure-conformance (class-name protocol-designator)
(let* ((protocol (typecase protocol-designator
(symbol (find-protocol protocol-designator))
(t protocol-designator)))
(protocol-name (protocol-name protocol))
(conforming-p nil))
(with-slots (name superprotocols methods options)
protocol
(loop for method in methods
for (name . raw-argument-class-list) = method
for argument-class-list = (substitute class-name
'*
raw-argument-class-list)
for real-argument-class-list = (mapcar #'find-class
argument-class-list)
when (null (funcall #'compute-applicable-methods-using-classes
(fdefinition name)
real-argument-class-list))
collect method into missing-methods
and do (warn (make-condition 'simple-style-warning
:format-control "Class ~A does not implement ~
method ~A with argument types ~
~A as required by ~
protocol ~A."
:format-arguments (list class-name
(first method)
real-argument-class-list
(protocol-name protocol))))
finally (setq conforming-p (null missing-methods)))
(let ((really-conforming-p
(and conforming-p
(every #'identity
;; We have to use MAPCAR because we
;; don't want short-circuiting.
(mapcar #'(lambda (superprotocol)
(ensure-conformance class-name
superprotocol))
superprotocols)))))
(ensure-method #'%conforms-to-p
'(lambda (x y) t)
:specializers (list (intern-eql-specializer (find-class class-name))
(intern-eql-specializer (find-protocol protocol-name))))
(ensure-method #'%really-conforms-to-p
`(lambda (x y) ,really-conforming-p)
:specializers (list (intern-eql-specializer (find-class class-name))
(intern-eql-specializer (find-protocol protocol-name))))))))
(defmacro implement-protocols (class protocols &body definitions)
`(progn
,@definitions
,@(mapcar #'(lambda (protocol)
`(ensure-conformance ',class ',protocol))
protocols)))
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