Language/OS - Multiplatform Resource Library/LANGUAGE OS.iso/pcl/sptmbr16.lha/construct.lisp

Text File | 1992-12-21 | 39.6 KB | 1,065 lines

;;;-*-Mode:LISP; Package:(PCL LISP 1000); Base:10; Syntax:Common-lisp -*-
;;;
;;; *************************************************************************
;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
;;; All rights reserved.
;;;
;;; Use and copying of this software and preparation of derivative works
;;; based upon this software are permitted.  Any distribution of this
;;; software or derivative works must comply with all applicable United
;;; States export control laws.
;;;
;;; This software is made available AS IS, and Xerox Corporation makes no
;;; warranty about the software, its performance or its conformity to any
;;; specification.
;;;
;;; Any person obtaining a copy of this software is requested to send their
;;; name and post office or electronic mail address to:
;;;   CommonLoops Coordinator
;;;   Xerox PARC
;;;   3333 Coyote Hill Rd.
;;;   Palo Alto, CA 94304
;;; (or send Arpanet mail to [e-mail])
;;;
;;; Suggestions, comments and requests for improvements are also welcome.
;;; *************************************************************************
;;;
;;;
;;; This file defines the defconstructor and other make-instance optimization
;;; mechanisms.
;;;

(in-package :pcl)

;;;
;;; defconstructor is used to define special purpose functions which just
;;; call make-instance with a symbol as the first argument.  The semantics
;;; of defconstructor is that it is equivalent to defining a function which
;;; just calls make-instance. The purpose of defconstructor is to provide
;;; PCL with a way of noticing these calls to make-instance so that it can
;;; optimize them.  Specific ports of PCL could just have their compiler
;;; spot these calls to make-instance and then call this code.  Having the
;;; special defconstructor facility is the best we can do portably.
;;;
;;;
;;; A call to defconstructor like:
;;;
;;;  (defconstructor make-foo foo (a b &rest r) a a :mumble b baz r)
;;;
;;; Is equivalent to a defun like:
;;;
;;;  (defun make-foo (a b &rest r)
;;;    (make-instance 'foo 'a a ':mumble b 'baz r))
;;;
;;; Calls like the following are also legal:
;;;
;;;  (defconstructor make-foo foo ())
;;;  (defconstructor make-bar bar () :x *x* :y *y*)
;;;  (defconstructor make-baz baz (a b c) a-b (list a b) b-c (list b c))
;;;
;;;
;;; The general idea of this implementation is that the expansion of the
;;; defconstructor form includes the creation of closure generators which
;;; can be called to create constructor code for the class.  The ways that
;;; a constructor can be optimized depends not only on the defconstructor
;;; form, but also on the state of the class and the generic functions in
;;; the initialization protocol.  Because of this, the determination of the
;;; form of constructor code to be used is a two part process.
;;;
;;; At compile time, make-constructor-code-generators looks at the actual
;;; defconstructor form and makes a list of appropriate constructor code
;;; generators.  All that is really taken into account here is whether
;;; any initargs are supplied in the call to make-instance, and whether
;;; any of those are constant.
;;;
;;; At constructor code generation time (see note about lazy evaluation)
;;; compute-constructor-code calls each of the constructor code generators
;;; to try to get code for this constructor.  Each generator looks at the
;;; state of the class and initialization protocol generic functions and
;;; decides whether its type of code is appropriate.  This depends on things
;;; like whether there are any applicable methods on initialize-instance,
;;; whether class slots are affected by initialization etc.
;;;
;;;
;;; Constructor objects are funcallable instances, the protocol followed to
;;; to compute the constructor code for them is quite similar to the protocol
;;; followed to compute the discriminator code for a generic function.  When
;;; the constructor is first loaded, we install as its code a function which
;;; will compute the actual constructor code the first time it is called.
;;;
;;; If there is an update to the class structure which might invalidate the
;;; optimized constructor, the special lazy constructor installer is put back
;;; so that it can compute the appropriate constructor when it is called.
;;; This is the same kind of lazy evaluation update strategy used elswhere
;;; in PCL.
;;;
;;; To allow for flexibility in the PCL implementation and to allow PCL users
;;; to specialize this constructor facility for their own metaclasses, there
;;; is an internal protocol followed by the code which loads and installs
;;; the constructors.  This is documented in the comments in the code.
;;;
;;; This code is also designed so that one of its levels, can be used to
;;; implement optimization of calls to make-instance which can't go through
;;; the defconstructor facility.  This has not been implemented yet, but the
;;; hooks are there.
;;;
;;;

(defmacro defconstructor
      (name class lambda-list &rest initialization-arguments)
  (expand-defconstructor class
             name
             lambda-list
             (copy-list initialization-arguments)))

(defun expand-defconstructor (class-name name lambda-list supplied-initargs)
  (let ((class (find-class class-name nil))
    (supplied-initarg-names
      (gathering1 (collecting)
        (iterate ((name (*list-elements supplied-initargs :by #'cddr)))
          (gather1 name)))))
    (when (null class)
      (error "defconstructor form being compiled (or evaluated) before~@
              class ~S is defined."
         class-name))
    `(progn
       ;; In order to avoid undefined function warnings, we want to tell
       ;; the compile time environment that a function with this name and
       ;; this argument list has been defined.  The portable way to do this
       ;; is with defun.
       (proclaim '(notinline ,name))
       (defun ,name ,lambda-list
     (declare (ignore ,@(extract-parameters lambda-list)))
     (error "Constructor ~S not loaded." ',name))

       ,(make-top-level-form `(defconstructor ,name)
                 '(load eval)
      `(load-constructor
         ',class-name
         ',(class-name (class-of class))
         ',name
         ',supplied-initarg-names
         ;; make-constructor-code-generators is called to return a list
         ;; of constructor code generators.  The actual interpretation
         ;; of this list is left to compute-constructor-code, but the
         ;; general idea is that it should be an plist where the keys
         ;; name a kind of constructor code and the values are generator
         ;; functions which return the actual constructor code.  The
         ;; constructor code is usually a closures over the arguments
         ;; to the generator.
         ,(make-constructor-code-generators class
                        name
                        lambda-list
                        supplied-initarg-names
                        supplied-initargs))))))

(defun load-constructor (class-name metaclass-name constructor-name
             supplied-initarg-names code-generators)
  (let ((class (find-class class-name nil)))
    (cond ((null class)
       (error "defconstructor form being loaded (or evaluated) before~@
                   class ~S is defined."
          class-name))
      ((neq (class-name (class-of class)) metaclass-name)
       (error "When defconstructor ~S was compiled, the metaclass of the~@
                   class ~S was ~S.  The metaclass is now ~S.~@
                   The constructor must be recompiled."
          constructor-name
          class-name
          metaclass-name
          (class-name (class-of class))))
      (t
       (load-constructor-internal class
                      constructor-name
                      supplied-initarg-names
                      code-generators)
       constructor-name))))

;;;
;;; The actual constructor objects.
;;;
(defclass constructor ()
     ((class                    ;The class with which this
    :initarg :class                ;constructor is associated.
    :reader constructor-class)        ;The actual class object,
                        ;not the class name.
                        ;
      (name                    ;The name of this constructor.
    :initform nil                ;This is the symbol in whose
    :initarg :name                ;function cell the constructor
    :reader constructor-name)        ;usually sits.  Of course, this
                        ;is optional.  defconstructor
                        ;makes named constructors, but
                        ;it is possible to manipulate
                        ;anonymous constructors also.
                        ;
      (code-type                ;The type of code currently in
    :initform nil                ;use by this constructor.  This
    :accessor constructor-code-type)    ;is mostly for debugging and
                        ;analysis purposes.
                        ;The lazy installer sets this
                        ;to LAZY.  The most basic and
                        ;least optimized type of code
                        ;is called FALLBACK.
                        ;
      (supplied-initarg-names            ;The names of the initargs this
    :initarg :supplied-initarg-names    ;constructor supplies when it
    :reader                    ;"calls" make-instance.
       constructor-supplied-initarg-names)    ;
                        ;
      (code-generators                ;Generators for the different
    :initarg :code-generators        ;types of code this constructor
    :reader constructor-code-generators))    ;could use.
  (:metaclass funcallable-standard-class))


;;;
;;; Because the value in the code-type slot should always correspond to the
;;; funcallable-instance-function of the constructor, this function should
;;; always be used to set the both at the same time.
;;;
(defun set-constructor-code (constructor code type)
  (set-funcallable-instance-function constructor code)
  (set-function-name constructor (constructor-name constructor))
  (setf (constructor-code-type constructor) type))


(defmethod print-object ((constructor constructor) stream)
  (printing-random-thing (constructor stream)
    (format stream
        "~S ~S (~S)"
        (or (class-name (class-of constructor)) "Constructor")
        (or (slot-value-or-default constructor 'name) "Anonymous")
        (slot-value-or-default constructor 'code-type))))

(defmethod describe-object ((constructor constructor) stream)
  (format stream
      "~S is a constructor for the class ~S.~%~
            The current code type is ~S.~%~
            Other possible code types are ~S."
      constructor (constructor-class constructor)
      (constructor-code-type constructor)
      (gathering1 (collecting)
        (doplist (key val) (constructor-code-generators constructor)
          (gather1 key)))))

;;;
;;; I am not in a hairy enough mood to make this implementation be metacircular
;;; enough that it can support a defconstructor for constructor objects.
;;;
(defun make-constructor (class name supplied-initarg-names code-generators)
  (make-instance 'constructor
         :class class
         :name name
         :supplied-initarg-names supplied-initarg-names
         :code-generators code-generators))

; This definition actually appears in std-class.lisp.
;(defmethod class-constructors ((class std-class))
;  (with-slots (plist) class (getf plist 'constructors)))

(defmethod add-constructor ((class slot-class)
                (constructor constructor))
  (with-slots (plist) class
    (pushnew constructor (getf plist 'constructors))))

(defmethod remove-constructor ((class slot-class)
                   (constructor constructor))
  (with-slots (plist) class
    (setf (getf plist 'constructors)
      (delete constructor (getf plist 'constructors)))))

(defmethod get-constructor ((class slot-class) name &optional (error-p t))
  (or (dolist (c (class-constructors class))
    (when (eq (constructor-name c) name) (return c)))
      (if error-p
      (error "Couldn't find a constructor with name ~S for class ~S."
         name class)
      ())))

;;;
;;; This is called to actually load a defconstructor constructor.  It must
;;; install the lazy installer in the function cell of the constructor name,
;;; and also add this constructor to the list of constructors the class has.
;;;
(defmethod load-constructor-internal
       ((class slot-class) name initargs generators)
  (let ((constructor (make-constructor class name initargs generators))
    (old (get-constructor class name nil)))
    (when old (remove-constructor class old))
    (install-lazy-constructor-installer constructor)
    (add-constructor class constructor)
    (setf (gdefinition name) constructor)))

(defmethod install-lazy-constructor-installer ((constructor constructor))
  (let ((class (constructor-class constructor)))
    (set-constructor-code constructor
              #'(lambda (&rest args)
                  (multiple-value-bind (code type)
                  (compute-constructor-code class constructor)
                (prog1 (apply code args)
                       (set-constructor-code constructor
                                 code
                                 type))))
              'lazy)))

;;;
;;; The interface to keeping the constructors updated.
;;;
;;; add-method and remove-method (for standard-generic-function and -method),
;;; promise to call maybe-update-constructors on the generic function and
;;; the method.
;;;
;;; The class update code promises to call update-constructors whenever the
;;; class is changed.  That is, whenever the supers, slots or options change.
;;; If user defined classes of constructor needs to be updated in more than
;;; these circumstances, they should use the dependent updating mechanism to
;;; make sure update-constructors is called.
;;;
;;; Bootstrapping concerns force the definitions of maybe-update-constructors
;;; and update-constructors to be in the file std-class.  For clarity, they
;;; also appear below.  Be sure to keep the definition here and there in sync.
;;;
;(defvar *initialization-generic-functions*
;     (list #'make-instance
;           #'default-initargs
;           #'allocate-instance
;           #'initialize-instance
;           #'shared-initialize))
;
;(defmethod maybe-update-constructors
;       ((generic-function generic-function)
;        (method method))
;  (when (memq generic-function *initialization-generic-functions*)
;    (labels ((recurse (class)
;           (update-constructors class)
;           (dolist (subclass (class-direct-subclasses class))
;         (recurse subclass))))
;      (when (classp (car (method-specializers method)))
;    (recurse (car (method-specializers method)))))))
;
;(defmethod update-constructors ((class slot-class))
;  (dolist (cons (class-constructors class))
;    (install-lazy-constructor-installer cons)))
;
;(defmethod update-constructors ((class class))
;  ())



;;;
;;; Here is the actual smarts for making the code generators and then trying
;;; each generator to get constructor code. This extensible mechanism allows
;;; new kinds of constructor code types to be added. A programmer defining a
;;; specialization of the constructor class can either use this mechanism to
;;; define new code types, or can override this mechanism by overriding the
;;; methods on make-constructor-code-generators and compute-constructor-code.
;;;
;;; The function defined by define-constructor-code-type will receive the
;;; class object, and the 4 original arguments to defconstructor. It can
;;; return a constructor code generator, or return nil if this type of code
;;; is determined to not be appropriate after looking at the defconstructor
;;; arguments.
;;;
;;; When compute-constructor-code is called, it first performs basic checks
;;; to make sure that the basic assumptions common to all the code types are
;;; valid.  (For details see method definition).  If any of the tests fail,
;;; the fallback constructor code type is used.  If none of the tests fail,
;;; the constructor code generators are called in order.  They receive 5
;;; arguments:
;;;
;;;   CLASS        the class the constructor is making instances of
;;;   WRAPPER      that class's wrapper
;;;   DEFAULTS     the result of calling class-default-initargs on class
;;;   INITIALIZE   the applicable methods on initialize-instance
;;;   SHARED       the applicable methosd on shared-initialize
;;;
;;; The first code generator to return code is used.  The code generators are
;;; called in reverse order of definition, so define-constructor-code-type
;;; forms which define better code should appear after ones that define less
;;; good code.  The fallback code type appears first.  Note that redefining a
;;; code type does not change its position in the list.  To do that,  define
;;; a new type at the end with the behavior.
;;;

(defvar *constructor-code-types* ())

(defmacro define-constructor-code-type (type arglist &body body)
  (let ((fn-name (intern (format nil
                 "CONSTRUCTOR-CODE-GENERATOR ~A ~A"
                 (package-name (symbol-package type))
                 (symbol-name type))
             *the-pcl-package*)))
    `(progn
       (defun ,fn-name ,arglist .,body)
       (load-define-constructor-code-type ',type ',fn-name))))

(defun load-define-constructor-code-type (type generator)
  (let ((old-entry (assq type *constructor-code-types*)))
    (if old-entry
    (setf (cadr old-entry) generator)
    (push (list type generator) *constructor-code-types*))
    type))

(defmethod make-constructor-code-generators
       ((class slot-class)
        name lambda-list supplied-initarg-names supplied-initargs)
  (cons 'list
    (gathering1 (collecting)
      (dolist (entry *constructor-code-types*)
        (let ((generator
            (funcall (cadr entry) class name lambda-list
                      supplied-initarg-names
                      supplied-initargs)))
          (when generator
        (gather1 `',(car entry))
        (gather1 generator)))))))

(defmethod compute-constructor-code ((class slot-class)
                     (constructor constructor))
  (let* ((proto (class-prototype class))
     (wrapper (class-wrapper class))
     (defaults (class-default-initargs class))
         (make
           (compute-applicable-methods (gdefinition 'make-instance) (list class)))
     (supplied-initarg-names
       (constructor-supplied-initarg-names constructor))
         (default
       (compute-applicable-methods (gdefinition 'default-initargs)
                       (list class supplied-initarg-names))) ;?
         (allocate
           (compute-applicable-methods (gdefinition 'allocate-instance)
                       (list class)))
         (initialize
           (compute-applicable-methods (gdefinition 'initialize-instance)
                       (list proto)))
         (shared
           (compute-applicable-methods (gdefinition 'shared-initialize)
                       (list proto t)))
     (code-generators
       (constructor-code-generators constructor)))
    (flet ((call-code-generator (generator)
         (when (null generator)
           (unless (setq generator (getf code-generators 'fallback))
         (error "No FALLBACK generator?")))
         (funcall generator class wrapper defaults initialize shared)))
      (if (or (cdr make)
          (cdr default)
          (cdr allocate)
          (not (check-initargs-1 class
                     supplied-initarg-names
                     (append initialize shared)
                     nil nil)))
      ;; These are basic shared assumptions, if one of the
      ;; has been violated, we have to resort to the fallback
      ;; case.  Any of these assumptions could be moved out
      ;; of here and into the individual code types if there
      ;; was a need to do so.
      (values (call-code-generator nil) 'fallback)
      ;; Otherwise try all the generators until one produces
      ;; code for us.
      (doplist (type generator) code-generators
        (let ((code (call-code-generator generator)))
          (when code (return (values code type)))))))))

;;;
;;; The facilities are useful for debugging, and to measure the performance
;;; boost from constructors.
;;;

(defun map-constructors (fn)
  (let ((nclasses 0)
    (nconstructors 0))
    (labels ((recurse (class)
           (incf nclasses)
           (dolist (constructor (class-constructors class))
         (incf nconstructors)
         (funcall fn constructor))
           (dolist (subclass (class-direct-subclasses class))
         (recurse subclass))))
      (recurse (find-class 't))
      (values nclasses nconstructors))))

(defun reset-constructors ()
  (multiple-value-bind (nclass ncons)
      (map-constructors #'install-lazy-constructor-installer )
    (format t "~&~D classes, ~D constructors." nclass ncons)))

(defun disable-constructors ()
  (multiple-value-bind (nclass ncons)
      (map-constructors
    #'(lambda (c)
        (let ((gen (getf (constructor-code-generators c) 'fallback)))
          (if (null gen)
          (error "No fallback constructor for ~S." c)
          (set-constructor-code c
                    (funcall gen
                         (constructor-class c)
                         () () () ())
                    'fallback)))))
    (format t "~&~D classes, ~D constructors." nclass ncons)))

(defun enable-constructors ()
  (reset-constructors))


;;;
;;; Helper functions and utilities that are shared by all of the code types
;;; and by the main compute-constructor-code method as well.
;;;

(defvar *standard-initialize-instance-method*
        (get-method #'initialize-instance
            ()
            (list *the-class-slot-object*)))

(defvar *standard-shared-initialize-method*
        (get-method #'shared-initialize
            ()
            (list *the-class-slot-object* *the-class-t*)))

(defun non-pcl-initialize-instance-methods-p (methods)
  (notevery #'(lambda (m) (eq m *standard-initialize-instance-method*))
        methods))

(defun non-pcl-shared-initialize-methods-p (methods)
  (notevery #'(lambda (m) (eq m *standard-shared-initialize-method*))
        methods))

(defun non-pcl-or-after-initialize-instance-methods-p (methods)
  (notevery #'(lambda (m) (or (eq m *standard-initialize-instance-method*)
                  (equal '(:after) (method-qualifiers m))))
        methods))

(defun non-pcl-or-after-shared-initialize-methods-p (methods)
  (notevery #'(lambda (m) (or (eq m *standard-shared-initialize-method*)
                  (equal '(:after) (method-qualifiers m))))
        methods))

;;;
;;; This returns two values.  The first is a vector which can be used as the
;;; initial value of the slots vector for the instance. The second is a symbol
;;; describing the initforms this class has.
;;;
;;;  If the first value is:
;;;
;;;    :unsupplied    no slot has an initform
;;;    :constants     all slots have either a constant initform
;;;                   or no initform at all
;;;    t              there is at least one non-constant initform
;;;
(defun compute-constant-vector (class)
  ;;(declare (values constants flag))
  (let* ((wrapper (class-wrapper class))
     (layout (wrapper-instance-slots-layout wrapper))
     (flag :unsupplied)
     (constants ()))
    (dolist (slotd (class-slots class))
      (let ((name (slot-definition-name slotd))
        (initform (slot-definition-initform slotd))
        (initfn (slot-definition-initfunction slotd)))
    (cond ((null (memq name layout)))
          ((null initfn)
           (push (cons name *slot-unbound*) constants))
          ((constantp initform)
           (push (cons name (eval initform)) constants)
           (when (eq flag ':unsupplied) (setq flag ':constants)))
          (t
           (push (cons name *slot-unbound*) constants)
           (setq flag 't)))))
    (let* ((constants-alist (sort constants #'(lambda (x y)
                        (memq (car y)
                              (memq (car x) layout)))))
       (constants-list (mapcar #'cdr constants-alist)))
    (values constants-list flag))))


;;;
;;; This takes a class and a list of initarg-names, and returns an alist
;;; indicating the positions of the slots those initargs may fill.  The
;;; order of the initarg-names argument is important of course, since we
;;; have to respect the rules about the leftmost initarg that fills a slot
;;; having precedence.  This function allows initarg names to appear twice
;;; in the list, it only considers the first appearance.
;;;
(defun compute-initarg-positions (class initarg-names)
  (let* ((layout (wrapper-instance-slots-layout (class-wrapper class)))
     (positions
       (gathering1 (collecting)
         (iterate ((slot-name (list-elements layout))
               (position (interval :from 0)))
           (gather1 (cons slot-name position)))))
     (slot-initargs
       (mapcar #'(lambda (slotd)
               (list (slot-definition-initargs slotd)
                 (or (cdr (assq (slot-definition-name slotd) positions))
                 ':class)))
           (class-slots class))))
    ;; Go through each of the initargs, and figure out what position
    ;; it fills by replacing the entries in slot-initargs it fills.
    (dolist (initarg initarg-names)
      (dolist (slot-entry slot-initargs)
    (let ((slot-initargs (car slot-entry)))
      (when (and (listp slot-initargs)
             (not (null slot-initargs))
             (memq initarg slot-initargs))
        (setf (car slot-entry) initarg)))))
    (gathering1 (collecting)
      (dolist (initarg initarg-names)
    (let ((positions (gathering1 (collecting)
               (dolist (slot-entry slot-initargs)
                 (when (eq (car slot-entry) initarg)
                   (gather1 (cadr slot-entry)))))))
      (when positions
        (gather1 (cons initarg positions))))))))


;;;
;;; The FALLBACK case allows anything.  This always works, and always appears
;;; as the last of the generators for a constructor.  It does a full call to
;;; make-instance.
;;;

(define-constructor-code-type fallback
        (class name arglist supplied-initarg-names supplied-initargs)
  (declare (ignore name supplied-initarg-names))
  `(function
     (lambda (&rest ignore)
       (declare (ignore ignore))
       (function
     (lambda ,arglist
       (make-instance
         ',(class-name class)
         ,@(gathering1 (collecting)
         (iterate ((tail (*list-tails supplied-initargs :by #'cddr)))
           (gather1 `',(car tail))
           (gather1 (cadr tail))))))))))

;;;
;;; The GENERAL case allows:
;;;   constant, unsupplied or non-constant initforms
;;;   constant or non-constant default initargs
;;;   supplied initargs
;;;   slot-filling initargs
;;;   :after methods on shared-initialize and initialize-instance
;;;
(define-constructor-code-type general
        (class name arglist supplied-initarg-names supplied-initargs)
  (declare (ignore name))
  (let ((raw-allocator (raw-instance-allocator class))
    (slots-fetcher (slots-fetcher class)))
    `(function
       (lambda (class .wrapper. defaults init shared)
     (multiple-value-bind (.constants.
                   .constant-initargs.
                   .initfns-initargs-and-positions.
                   .supplied-initarg-positions.
                   .shared-initfns.
                   .initfns.)
         (general-generator-internal class
                     defaults
                     init
                     shared
                     ',supplied-initarg-names
                     ',supplied-initargs)
       .supplied-initarg-positions.
       (when (and .constants.
              (null (non-pcl-or-after-initialize-instance-methods-p
                  init))
              (null (non-pcl-or-after-shared-initialize-methods-p
                  shared)))
         (function
           (lambda ,arglist
         (declare #.*optimize-speed*)
         (let* ((.instance. (,raw-allocator .wrapper. .constants.))
            (.slots. (,slots-fetcher .instance.))
            (.positions. .supplied-initarg-positions.)
            (.initargs. .constant-initargs.))
           .positions.

           (dolist (entry .initfns-initargs-and-positions.)
             (let ((val (funcall (car entry)))
               (initarg (cadr entry)))
               (when initarg
             (push val .initargs.)
             (push initarg .initargs.))
               (dolist (pos (cddr entry))
             (setf (%instance-ref .slots. pos) val))))

           ,@(gathering1 (collecting)
               (doplist (initarg value) supplied-initargs
             (unless (constantp value)
               (gather1 `(let ((.value. ,value))
                       (push .value. .initargs.)
                       (push ',initarg .initargs.)
                       (dolist (.p. (pop .positions.))
                     (setf (%instance-ref .slots. .p.)
                           .value.)))))))

           (dolist (fn .shared-initfns.)
             (apply fn .instance. t .initargs.))
           (dolist (fn .initfns.)
             (apply fn .instance. .initargs.))

           .instance.)))))))))

(defun general-generator-internal
       (class defaults init shared supplied-initarg-names supplied-initargs)
  (flet ((bail-out () (return-from general-generator-internal nil)))
    (let* ((constants (compute-constant-vector class))
       (layout (wrapper-instance-slots-layout (class-wrapper class)))
       (initarg-positions
         (compute-initarg-positions class
                    (append supplied-initarg-names
                        (mapcar #'car defaults))))
       (initfns-initargs-and-positions ())
       (supplied-initarg-positions ())
       (constant-initargs ())
       (used-positions ()))

      ;;
      ;; Go through each of the supplied initargs for three reasons.
      ;;
      ;;   - If it fills a class slot, bail out.
      ;;   - If its a constant form, fill the constant vector.
      ;;   - Otherwise remember the positions no two initargs
      ;;     will try to fill the same position, since compute
      ;;     initarg positions already took care of that, but
      ;;     we do need to know what initforms will and won't
      ;;     be needed.
      ;;
      (doplist (initarg val) supplied-initargs
    (let ((positions (cdr (assq initarg initarg-positions))))
      (cond ((memq :class positions) (bail-out))
        ((constantp val)
         (setq val (eval val))
         (push val constant-initargs)
         (push initarg constant-initargs)
         (dolist (pos positions) (setf (svref constants pos) val)))
        (t
         (push positions supplied-initarg-positions)))
      (setq used-positions (append positions used-positions))))
      ;;
      ;; Go through each of the default initargs, for three reasons.
      ;;
      ;;   - If it fills a class slot, bail out.
      ;;   - If it is a constant, and it does fill a slot, put that
      ;;     into the constant vector.
      ;;   - If it isn't a constant, record its initfn and position.
      ;;
      (dolist (default defaults)
    (let* ((name (car default))
           (initfn (cadr default))
           (form (caddr default))
           (value ())
           (positions (cdr (assq name initarg-positions))))
      (unless (memq name supplied-initarg-names)
        (cond ((memq :class positions) (bail-out))
          ((constantp form)
           (setq value (eval form))
           (push value constant-initargs)
           (push name constant-initargs)
           (dolist (pos positions)
             (setf (svref constants pos) value)))
          (t
           (push (list* initfn name positions)
             initfns-initargs-and-positions)))
        (setq used-positions (append positions used-positions)))))
      ;;
      ;; Go through each of the slot initforms:
      ;;
      ;;    - If its position has already been filled, do nothing.
      ;;      The initfn won't need to be called, and the slot won't
      ;;      need to be touched.
      ;;    - If it is a class slot, and has an initform, bail out.
      ;;    - If its a constant or unsupplied, ignore it, it is
      ;;      already in the constant vector.
      ;;    - Otherwise, record its initfn and position
      ;;
      (dolist (slotd (class-slots class))
    (let* ((alloc (slot-definition-allocation slotd))
           (name (slot-definition-name slotd))
           (form (slot-definition-initform slotd))
           (initfn (slot-definition-initfunction slotd))
           (position (position name layout)))
      (cond ((neq alloc :instance)
         (unless (null initfn)
           (bail-out)))
        ((member position used-positions))
        ((or (constantp form)
             (null initfn)))
        (t
         (push (list initfn nil position)
               initfns-initargs-and-positions)))))

      (values constants
          constant-initargs
          (nreverse initfns-initargs-and-positions)
          (nreverse supplied-initarg-positions)
          (mapcar #'method-function
              (remove *standard-shared-initialize-method* shared))
          (mapcar #'method-function
              (remove *standard-initialize-instance-method* init))))))


;;;
;;; The NO-METHODS case allows:
;;;   constant, unsupplied or non-constant initforms
;;;   constant or non-constant default initargs
;;;   supplied initargs that are arguments to constructor, or constants
;;;   slot-filling initargs
;;;

(define-constructor-code-type no-methods
        (class name arglist supplied-initarg-names supplied-initargs)
  (declare (ignore name))
  (let ((raw-allocator (raw-instance-allocator class))
    (slots-fetcher (slots-fetcher class)))
    `(function
       (lambda (class .wrapper. defaults init shared)
     (multiple-value-bind (.constants.
                   .initfns-and-positions.
                   .supplied-initarg-positions.)
         (no-methods-generator-internal class
                        defaults
                        ',supplied-initarg-names
                        ',supplied-initargs)
       .initfns-and-positions.
       .supplied-initarg-positions.
       (when (and .constants.
              (null (non-pcl-initialize-instance-methods-p init))
              (null (non-pcl-shared-initialize-methods-p shared)))
         #'(lambda ,arglist
         (declare #.*optimize-speed*)
         (let* ((.instance. (,raw-allocator .wrapper. .constants.))
            (.slots. (,slots-fetcher .instance.))
            (.positions. .supplied-initarg-positions.))
           .positions.

           (dolist (entry .initfns-and-positions.)
             (let ((val (funcall (car entry))))
               (dolist (pos (cdr entry))
             (setf (%instance-ref .slots. pos) val))))

           ,@(gathering1 (collecting)
               (doplist (initarg value) supplied-initargs
             (unless (constantp value)
               (gather1
                 `(let ((.value. ,value))
                (dolist (.p. (pop .positions.))
                  (setf (%instance-ref .slots. .p.) .value.)))))))

           .instance.))))))))

(defun no-methods-generator-internal
       (class defaults supplied-initarg-names supplied-initargs)
  (flet ((bail-out () (return-from no-methods-generator-internal nil)))
    (let* ((constants    (compute-constant-vector class))
       (layout (wrapper-instance-slots-layout (class-wrapper class)))
       (initarg-positions
         (compute-initarg-positions class
                    (append supplied-initarg-names
                        (mapcar #'car defaults))))
       (initfns-and-positions ())
       (supplied-initarg-positions ())
       (used-positions ()))
      ;;
      ;; Go through each of the supplied initargs for three reasons.
      ;;
      ;;   - If it fills a class slot, bail out.
      ;;   - If its a constant form, fill the constant vector.
      ;;   - Otherwise remember the positions, no two initargs
      ;;     will try to fill the same position, since compute
      ;;     initarg positions already took care of that, but
      ;;     we do need to know what initforms will and won't
      ;;     be needed.
      ;;
      (doplist (initarg val) supplied-initargs
    (let ((positions (cdr (assq initarg initarg-positions))))
      (cond ((memq :class positions) (bail-out))
        ((constantp val)
         (setq val (eval val))
         (dolist (pos positions)
           (setf (svref constants pos) val)))
        (t
         (push positions supplied-initarg-positions)))
      (setq used-positions (append positions used-positions))))
      ;;
      ;; Go through each of the default initargs, for three reasons.
      ;;
      ;;   - If it fills a class slot, bail out.
      ;;   - If it is a constant, and it does fill a slot, put that
      ;;     into the constant vector.
      ;;   - If it isn't a constant, record its initfn and position.
      ;;
      (dolist (default defaults)
    (let* ((name (car default))
           (initfn (cadr default))
           (form (caddr default))
           (value ())
           (positions (cdr (assq name initarg-positions))))
      (unless (memq name supplied-initarg-names)
        (cond ((memq :class positions) (bail-out))
          ((constantp form)
           (setq value (eval form))
           (dolist (pos positions)
             (setf (svref constants pos) value)))
          (t
           (push (cons initfn positions)
             initfns-and-positions)))
        (setq used-positions (append positions used-positions)))))
      ;;
      ;; Go through each of the slot initforms:
      ;;
      ;;    - If its position has already been filled, do nothing.
      ;;      The initfn won't need to be called, and the slot won't
      ;;      need to be touched.
      ;;    - If it is a class slot, and has an initform, bail out.
      ;;    - If its a constant or unsupplied, do nothing, we know
      ;;      that it is already in the constant vector.
      ;;    - Otherwise, record its initfn and position
      ;;
      (dolist (slotd (class-slots class))
    (let* ((alloc (slot-definition-allocation slotd))
           (name (slot-definition-name slotd))
           (form (slot-definition-initform slotd))
           (initfn (slot-definition-initfunction slotd))
           (position (position name layout)))
      (cond ((neq alloc :instance)
         (unless (null initfn)
           (bail-out)))
        ((member position used-positions))
        ((or (constantp form)
             (null initfn)))
        (t
         (push (list initfn position) initfns-and-positions)))))

      (values constants
          (nreverse initfns-and-positions)
          (nreverse supplied-initarg-positions)))))


;;;
;;; The SIMPLE-SLOTS case allows:
;;;   constant or unsupplied initforms
;;;   constant default initargs
;;;   supplied initargs
;;;   slot filling initargs
;;;

(define-constructor-code-type simple-slots
        (class name arglist supplied-initarg-names supplied-initargs)
  (declare (ignore name))
  (let ((raw-allocator (raw-instance-allocator class))
    (slots-fetcher (slots-fetcher class)))
    `(function
       (lambda (class .wrapper. defaults init shared)
     (when (and (null (non-pcl-initialize-instance-methods-p init))
            (null (non-pcl-shared-initialize-methods-p shared)))
       (multiple-value-bind (.constants. .supplied-initarg-positions.)
           (simple-slots-generator-internal class
                        defaults
                        ',supplied-initarg-names
                        ',supplied-initargs)
         (when .constants.
           (function
         (lambda ,arglist
           (declare #.*optimize-speed*)
           (let* ((.instance. (,raw-allocator .wrapper. .constants.))
              (.slots. (,slots-fetcher .instance.))
              (.positions. .supplied-initarg-positions.))
             .positions.

             ,@(gathering1 (collecting)
             (doplist (initarg value) supplied-initargs
               (unless (constantp value)
                 (gather1
                   `(let ((.value. ,value))
                  (dolist (.p. (pop .positions.))
                    (setf (%instance-ref .slots. .p.) .value.)))))))

             .instance.))))))))))

(defun simple-slots-generator-internal
       (class defaults supplied-initarg-names supplied-initargs)
  (flet ((bail-out () (return-from simple-slots-generator-internal nil)))
    (let* ((constants (compute-constant-vector class))
       (layout (wrapper-instance-slots-layout (class-wrapper class)))
       (initarg-positions
         (compute-initarg-positions class
                    (append supplied-initarg-names
                        (mapcar #'car defaults))))
       (supplied-initarg-positions ())
       (used-positions ()))
      ;;
      ;; Go through each of the supplied initargs for three reasons.
      ;;
      ;;   - If it fills a class slot, bail out.
      ;;   - If its a constant form, fill the constant vector.
      ;;   - Otherwise remember the positions, no two initargs
      ;;     will try to fill the same position, since compute
      ;;     initarg positions already took care of that, but
      ;;     we do need to know what initforms will and won't
      ;;     be needed.
      ;;
      (doplist (initarg val) supplied-initargs
    (let ((positions (cdr (assq initarg initarg-positions))))
      (cond ((memq :class positions) (bail-out))
        ((constantp val)
         (setq val (eval val))
         (dolist (pos positions)
           (setf (svref constants pos) val)))
        (t
         (push positions supplied-initarg-positions)))
      (setq used-positions (append used-positions positions))))
      ;;
      ;; Go through each of the default initargs for three reasons.
      ;;
      ;;   - If it isn't a constant form, bail out.
      ;;   - If it fills a class slot, bail out.
      ;;   - If it is a constant, and it does fill a slot, put that
      ;;     into the constant vector.
      ;;
      (dolist (default defaults)
    (let* ((name (car default))
           (form (caddr default))
           (value ())
           (positions (cdr (assq name initarg-positions))))
      (unless (memq name supplied-initarg-names)
        (cond ((memq :class positions) (bail-out))
          ((not (constantp form))
           (bail-out))
          (t
           (setq value (eval form))
           (dolist (pos positions)
             (setf (svref constants pos) value)))))))
      ;;
      ;; Go through each of the slot initforms:
      ;;
      ;;    - If its position has already been filled, do nothing.
      ;;      The initfn won't need to be called, and the slot won't
      ;;      need to be touched, we are OK.
      ;;    - If it has a non-constant initform, bail-out.  This
      ;;      case doesn't handle those.
      ;;    - If it has a constant or unsupplied initform we don't
      ;;      really need to do anything, the value is in the
      ;;      constants vector.
      ;;
      (dolist (slotd (class-slots class))
    (let* ((alloc (slot-definition-allocation slotd))
           (name (slot-definition-name slotd))
           (form (slot-definition-initform slotd))
           (initfn (slot-definition-initfunction slotd))
           (position (position name layout)))
      (cond ((neq alloc :instance)
         (unless (null initfn)
           (bail-out)))
        ((member position used-positions))
        ((or (constantp form)
             (null initfn)))
        (t
         (bail-out)))))

      (values constants (nreverse supplied-initarg-positions)))))