3 ;;; Method combination implementation
5 ;;; (c) 2009 Straylight/Edgeware
8 ;;;----- Licensing notice ---------------------------------------------------
10 ;;; This file is part of the Sensible Object Design, an object system for C.
12 ;;; SOD is free software; you can redistribute it and/or modify
13 ;;; it under the terms of the GNU General Public License as published by
14 ;;; the Free Software Foundation; either version 2 of the License, or
15 ;;; (at your option) any later version.
17 ;;; SOD is distributed in the hope that it will be useful,
18 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;;; GNU General Public License for more details.
22 ;;; You should have received a copy of the GNU General Public License
23 ;;; along with SOD; if not, write to the Free Software Foundation,
24 ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
28 ;;;--------------------------------------------------------------------------
31 (export 'basic-message)
32 (defclass basic-message (sod-message)
33 ((argument-tail :type list :reader sod-message-argument-tail)
34 (no-varargs-tail :type list :reader sod-message-no-varargs-tail))
36 "Base class for built-in message classes.
38 Provides the basic functionality for the built-in method combinations.
39 This is a separate class so that `special effect' messages can avoid
40 inheriting its default behaviour.
42 The function type protocol is implemented on `basic-message' using slot
43 reader methods. The actual values are computed on demand."))
45 (define-on-demand-slot basic-message argument-tail (message)
48 (if (or (eq arg :ellipsis) (argument-name arg)) arg
49 (make-argument (make-instance 'temporary-argument
52 (argument-type arg))))
53 (c-function-arguments (sod-message-type message)))))
55 (define-on-demand-slot basic-message no-varargs-tail (message)
57 (if (eq arg :ellipsis)
58 (make-argument *sod-ap* (c-type va-list))
60 (sod-message-argument-tail message)))
62 (defmethod sod-message-method-class
63 ((message basic-message) (class sod-class) pset)
64 (let ((role (get-property pset :role :keyword nil)))
66 ((:before :after) 'daemon-direct-method)
67 (:around 'delegating-direct-method)
68 ((nil) (error "How odd: a primary method slipped through the net"))
69 (t (error "Unknown method role ~A" role)))))
71 (export 'simple-message)
72 (defclass simple-message (basic-message)
75 "Base class for messages with `simple' method combinations.
77 A simple method combination is one which has only one method role other
78 than the `before', `after' and `around' methods provided by
79 `basic-message'. We call these `primary' methods, and the programmer
80 designates them by not specifying an explicit role.
82 If the programmer doesn't define any primary methods then the effective
83 method is null -- i.e., the method entry pointer shows up as a null
86 (defmethod sod-message-method-class
87 ((message simple-message) (class sod-class) pset)
88 (if (get-property pset :role :keyword nil)
90 (primary-method-class message)))
92 (defmethod primary-method-class ((message simple-message))
95 ;;;--------------------------------------------------------------------------
96 ;;; Direct method classes.
98 (export '(basic-direct-method sod-method-role))
99 (defclass basic-direct-method (sod-method)
100 ((role :initarg :role :type symbol :reader sod-method-role)
101 (function-type :type c-function-type :reader sod-method-function-type))
103 "Base class for built-in direct method classes.
105 Provides the basic functionality for the built-in direct-method classes.
106 This is a separate class so that `special effect' methods can avoid
107 inheriting its default behaviour and slots.
109 A basic method can be assigned a `role', which may be set either as an
110 initarg or using the `:role' property. Roles are used for method
113 The function type protocol is implemented on `basic-direct-method' using
114 slot reader methods."))
116 (defmethod shared-initialize :after
117 ((method basic-direct-method) slot-names &key pset)
118 (declare (ignore slot-names))
119 (default-slot (method 'role) (get-property pset :role :keyword nil)))
121 (define-on-demand-slot basic-direct-method function-type (method)
122 (let ((type (sod-method-type method)))
123 (c-type (fun (lisp (c-type-subtype type))
124 ("me" (* (class (sod-method-class method))))
125 . (c-function-arguments type)))))
127 (defmethod sod-method-function-name ((method basic-direct-method))
128 (with-slots ((class %class) role message) method
129 (format nil "~A__~@[~(~A~)_~]method_~A__~A" class role
130 (sod-class-nickname (sod-message-class message))
131 (sod-message-name message))))
133 (export 'daemon-direct-method)
134 (defclass daemon-direct-method (basic-direct-method)
137 "A daemon direct method is invoked for side effects and cannot override.
139 This is the direct method class for `before' and `after' methods, which
140 cannot choose to override the remaining methods and are not involved in
141 the computation of the final result.
143 In C terms, a daemon method must return `void', and is not passed a
144 `next_method' pointer."))
146 (defmethod check-method-type ((method daemon-direct-method)
147 (message sod-message)
148 (type c-function-type))
149 (with-slots ((msgtype %type)) message
150 (unless (c-type-equal-p (c-type-subtype type) (c-type void))
151 (error "Method return type ~A must be `void'" (c-type-subtype type)))
152 (unless (argument-lists-compatible-p (c-function-arguments msgtype)
153 (c-function-arguments type))
154 (error "Method arguments ~A don't match message ~A" type msgtype))))
156 (export 'delegating-direct-method)
157 (defclass delegating-direct-method (basic-direct-method)
158 ((next-method-type :type c-function-type
159 :reader sod-method-next-method-type))
161 "A delegating direct method can choose to override other methods.
163 This is the direct method class for `around' and standard-method-
164 combination primary methods, which are given the choice of computing the
165 entire method's result or delegating to (usually) less-specific methods.
167 In C terms, a delegating method is passed a `next_method' pointer so that
168 it can delegate part of its behaviour. (A delegating direct method for a
169 varargs message is also given an additional `va_list' argument,
170 conventionally named `sod__ap_master', which it is expected to pass on to
171 its `next_method' function if necessary.)
173 The function type protocol is implemented on `delegating-direct-method'
174 using slot reader methods.."))
176 (define-on-demand-slot delegating-direct-method next-method-type (method)
177 (let* ((message (sod-method-message method))
178 (return-type (c-type-subtype (sod-message-type message)))
179 (msgargs (sod-message-argument-tail message))
180 (arguments (if (varargs-message-p message)
181 (cons (make-argument *sod-master-ap*
185 (c-type (fun (lisp return-type)
186 ("me" (* (class (sod-method-class method))))
189 (define-on-demand-slot delegating-direct-method function-type (method)
190 (let* ((message (sod-method-message method))
191 (type (sod-method-type method))
192 (method-args (c-function-arguments type)))
193 (c-type (fun (lisp (c-type-subtype type))
194 ("me" (* (class (sod-method-class method))))
195 ("next_method" (* (lisp (commentify-function-type
196 (sod-method-next-method-type
199 (if (varargs-message-p message)
200 (cons (make-argument *sod-master-ap*
205 ;;;--------------------------------------------------------------------------
206 ;;; Effective method classes.
208 (export '(basic-effective-method
209 effective-method-around-methods effective-method-before-methods
210 effective-method-after-methods))
211 (defclass basic-effective-method (effective-method)
212 ((around-methods :initarg :around-methods :initform nil
213 :type list :reader effective-method-around-methods)
214 (before-methods :initarg :before-methods :initform nil
215 :type list :reader effective-method-before-methods)
216 (after-methods :initarg :after-methods :initform nil
217 :type list :reader effective-method-after-methods)
218 (basic-argument-names :type list
219 :reader effective-method-basic-argument-names)
220 (functions :type list :reader effective-method-functions))
222 "Base class for built-in effective method classes.
224 This class maintains lists of the applicable `before', `after' and
225 `around' methods and provides behaviour for invoking these methods
228 The argument names protocol is implemented on `basic-effective-method'
229 using a slot reader method."))
231 (define-on-demand-slot basic-effective-method basic-argument-names (method)
232 (let ((message (effective-method-message method)))
233 (mapcar #'argument-name
234 (sod-message-no-varargs-tail message))))
236 (defmethod effective-method-function-name ((method effective-method))
237 (let* ((class (effective-method-class method))
238 (message (effective-method-message method))
239 (message-class (sod-message-class message)))
240 (format nil "~A__emethod_~A__~A"
242 (sod-class-nickname message-class)
243 (sod-message-name message))))
245 (define-on-demand-slot basic-effective-method functions (method)
246 (compute-method-entry-functions method))
248 (export 'simple-effective-method)
249 (defclass simple-effective-method (basic-effective-method)
250 ((primary-methods :initarg :primary-methods :initform nil
251 :type list :reader effective-method-primary-methods))
253 "Effective method counterpart to `simple-message'."))
255 (defmethod shared-initialize :after
256 ((method simple-effective-method) slot-names &key direct-methods)
257 (declare (ignore slot-names))
258 (categorize (method direct-methods :bind ((role (sod-method-role method))))
259 ((primary (null role))
260 (before (eq role :before))
261 (after (eq role :after))
262 (around (eq role :around)))
263 (with-slots (primary-methods before-methods after-methods around-methods)
265 (setf primary-methods primary
266 before-methods before
267 after-methods (reverse after)
268 around-methods around))))
270 ;;;--------------------------------------------------------------------------
273 (defmethod shared-initialize :after
274 ((codegen method-codegen) slot-names &key)
275 (declare (ignore slot-names))
276 (with-slots (message target) codegen
278 (if (eq (c-type-subtype (sod-message-type message)) (c-type void))
282 ;;;--------------------------------------------------------------------------
283 ;;; Invoking direct methods.
285 (export 'basic-effective-method-body)
286 (defun basic-effective-method-body (codegen target method body)
287 "Build the common method-invocation structure.
289 Writes to CODEGEN some basic method-invocation instructions. It invokes
290 the `around' methods, from most- to least-specific. If they all delegate,
291 then the `before' methods are run, most-specific first; next, the
292 instructions generated by BODY (invoked with a target argument); then, the
293 `after' methods are run, least-specific first; and, finally, the value
294 delivered by the BODY is returned to the `around' methods. The result
295 returned by the outermost `around' method -- or, if there are none,
296 delivered by the BODY -- is finally delivered to the TARGET."
298 (with-slots (message (class %class)
299 before-methods after-methods around-methods)
301 (let* ((message-type (sod-message-type message))
302 (return-type (c-type-subtype message-type))
303 (basic-tail (effective-method-basic-argument-names method)))
304 (flet ((method-kernel (target)
305 (dolist (before before-methods)
306 (invoke-method codegen :void basic-tail before))
307 (if (null after-methods)
308 (funcall body target)
309 (convert-stmts codegen target return-type
311 (funcall body target)
312 (dolist (after (reverse after-methods))
313 (invoke-method codegen :void
314 basic-tail after)))))))
315 (invoke-delegation-chain codegen target basic-tail
316 around-methods #'method-kernel)))))
318 ;;;--------------------------------------------------------------------------
319 ;;; Method entry points.
321 (defparameter *method-entry-inline-threshold* 200
322 "Threshold below which effective method bodies are inlined into entries.
324 After the effective method body has been computed, we calculate its
325 metric, multiply by the number of entries we need to generate, and compare
326 it with this threshold. If the metric is below the threshold then we
327 fold the method body into the entry functions; otherwise we split the
328 effective method out into its own function.")
330 (defmethod method-entry-function-name
331 ((method effective-method) (chain-head sod-class) role)
332 (let* ((class (effective-method-class method))
333 (message (effective-method-message method))
334 (message-class (sod-message-class message)))
335 (if (or (not (slot-boundp method 'functions))
336 (slot-value method 'functions))
337 (format nil "~A__mentry~@[__~(~A~)~]_~A__~A__chain_~A"
339 (sod-class-nickname message-class)
340 (sod-message-name message)
341 (sod-class-nickname chain-head))
344 (defmethod method-entry-slot-name ((entry method-entry))
345 (let* ((method (method-entry-effective-method entry))
346 (message (effective-method-message method))
347 (name (sod-message-name message))
348 (role (method-entry-role entry)))
349 (method-entry-slot-name-by-role entry role name)))
351 (defmethod method-entry-function-type ((entry method-entry))
352 (let* ((method (method-entry-effective-method entry))
353 (message (effective-method-message method))
354 (type (sod-message-type message))
355 (tail (ecase (method-entry-role entry)
356 ((nil) (sod-message-argument-tail message))
357 (:valist (sod-message-no-varargs-tail message)))))
358 (c-type (fun (lisp (c-type-subtype type))
359 ("me" (* (class (method-entry-chain-tail entry))))
362 (defmethod make-method-entries ((method basic-effective-method)
363 (chain-head sod-class)
364 (chain-tail sod-class))
366 (message (effective-method-message method)))
368 (push (make-instance 'method-entry
369 :method method :role role
370 :chain-head chain-head
371 :chain-tail chain-tail)
373 (when (varargs-message-p message) (make :valist))
377 (defmethod compute-method-entry-functions ((method basic-effective-method))
379 ;; OK, there's quite a lot of this, so hold tight.
381 ;; The first thing we need to do is find all of the related objects. This
382 ;; is a bit verbose but fairly straightforward.
384 ;; Next, we generate the effective method body -- using `compute-effective-
385 ;; method-body' of all things. This gives us the declarations and body for
386 ;; an effective method function, but we don't have an actual function yet.
388 ;; Now we look at the chains which are actually going to need a method
389 ;; entry: only those chains whose tail (most specific) class is a
390 ;; superclass of the class which defined the message need an entry. We
391 ;; build a list of these tail classes.
393 ;; Having done this, we decide whether it's better to generate a standalone
394 ;; effective-method function and call it from each of the method entries,
395 ;; or to inline the effective method body into each of the entries.
397 ;; Most of the complexity here comes from (a) dealing with the two
398 ;; different strategies for constructing method entry functions and (b)
399 ;; (unsurprisingly) the mess involved with dealing with varargs messages.
401 (let* ((message (effective-method-message method))
402 (class (effective-method-class method))
403 (message-class (sod-message-class message))
404 (return-type (c-type-subtype (sod-message-type message)))
405 (codegen (make-instance 'method-codegen
410 ;; Method entry details.
411 (chain-tails (remove-if-not (lambda (super)
412 (sod-subclass-p super message-class))
414 (sod-class-chains class))))
415 (n-entries (length chain-tails))
416 (raw-entry-args (sod-message-argument-tail message))
417 (entry-args (sod-message-no-varargs-tail message))
418 (parm-n (let ((tail (last raw-entry-args 2)))
419 (and tail (eq (cadr tail) :ellipsis) (car tail))))
420 (entry-target (codegen-target codegen))
422 ;; Effective method function details.
423 (emf-name (effective-method-function-name method))
424 (ilayout-type (c-type (* (struct (ilayout-struct-tag class)))))
425 (emf-arg-tail (sod-message-no-varargs-tail message))
426 (emf-type (c-type (fun (lisp return-type)
427 ("sod__obj" (lisp ilayout-type))
430 (flet ((setup-entry (tail)
431 (let ((head (sod-class-chain-head tail)))
432 (codegen-push codegen)
433 (ensure-var codegen "sod__obj" ilayout-type
434 (make-convert-to-ilayout-inst class
437 (let* ((head (sod-class-chain-head tail))
438 (role (if parm-n :valist nil))
439 (name (method-entry-function-name method head role))
440 (type (c-type (fun (lisp return-type)
441 ("me" (* (class tail)))
443 (codegen-pop-function codegen name type)
445 ;; If this is a varargs method then we've made the
446 ;; `:valist' role. Also make the `nil' role.
448 (let ((call (make-call-inst name
450 (mapcar #'argument-name
452 (main (method-entry-function-name method head nil))
453 (main-type (c-type (fun (lisp return-type)
454 ("me" (* (class tail)))
456 (codegen-push codegen)
457 (ensure-var codegen *sod-ap* (c-type va-list))
459 (make-va-start-inst *sod-ap*
460 (argument-name parm-n)))
461 (convert-stmts codegen entry-target return-type
463 (deliver-expr codegen target call)))
464 (emit-inst codegen (make-va-end-inst *sod-ap*))
465 (codegen-pop-function codegen main main-type))))))
467 ;; Generate the method body. We'll work out what to do with it later.
468 (codegen-push codegen)
469 (let* ((result (if (eq return-type c-type-void) nil
470 (temporary-var codegen return-type)))
471 (emf-target (or result :void)))
472 (compute-effective-method-body method codegen emf-target)
473 (multiple-value-bind (vars insts) (codegen-pop codegen)
474 (cond ((or (= n-entries 1)
475 (<= (* n-entries (reduce #'+ insts :key #'inst-metric))
476 *method-entry-inline-threshold*))
478 ;; The effective method body is simple -- or there's only
479 ;; one of them. We'll inline the method body into the entry
481 (dolist (tail chain-tails)
484 (if (typep var 'var-inst)
485 (ensure-var codegen (inst-name var)
486 (inst-type var) (inst-init var))
487 (emit-decl codegen var)))
488 (emit-insts codegen insts)
489 (deliver-expr codegen entry-target result)
490 (finish-entry tail)))
494 ;; The effective method body is complicated and we'd need
495 ;; more than one copy. We'll generate an effective method
496 ;; function and call it a lot.
497 (codegen-build-function codegen emf-name emf-type vars
498 (nconc insts (and result
499 (list (make-return-inst result)))))
501 (let ((call (make-call-inst emf-name
502 (cons "sod__obj" (mapcar #'argument-name
504 (dolist (tail chain-tails)
506 (deliver-expr codegen entry-target call)
507 (finish-entry tail)))))))
509 (codegen-functions codegen))))
511 (defmethod compute-method-entry-functions
512 ((method simple-effective-method))
513 (if (effective-method-primary-methods method)
517 (defmethod compute-effective-method-body
518 ((method simple-effective-method) codegen target)
519 (basic-effective-method-body codegen target method
521 (simple-method-body method
525 ;;;--------------------------------------------------------------------------
526 ;;; Standard method combination.
528 (export 'standard-message)
529 (defclass standard-message (simple-message)
532 "Message class for standard method combinations.
534 Standard method combination is a simple method combination where the
535 primary methods are invoked as a delegation chain, from most- to
538 (export 'standard-effective-method)
539 (defclass standard-effective-method (simple-effective-method) ()
540 (:documentation "Effective method counterpart to `standard-message'."))
542 (defmethod primary-method-class ((message standard-message))
543 'delegating-direct-method)
545 (defmethod sod-message-effective-method-class ((message standard-message))
546 'standard-effective-method)
548 (defmethod simple-method-body
549 ((method standard-effective-method) codegen target)
550 (invoke-delegation-chain codegen
552 (effective-method-basic-argument-names method)
553 (effective-method-primary-methods method)
556 ;;;----- That's all, folks --------------------------------------------------