;;;; that part of DEFSTRUCT implementation which is needed not just
;;;; in the target Lisp but also in the cross-compilation host

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.

(in-package "SB!KERNEL")

(/show0 "code/defstruct.lisp 15")

;;;; getting LAYOUTs

;;; Return the compiler layout for NAME. (The class referred to by
;;; NAME must be a structure-like class.)
(defun compiler-layout-or-lose (name)
  (let ((res (info :type :compiler-layout name)))
    (cond ((not res)
           (error "Class is not yet defined or was undefined: ~S" name))
          ((not (typep (layout-info res) 'defstruct-description))
           (error "Class is not a structure class: ~S" name))
          (t
           (sb!int:check-deprecated-type name)
           res))))

(defun compiler-layout-ready-p (name)
  (let ((layout (info :type :compiler-layout name)))
    (and layout (typep (layout-info layout) 'defstruct-description))))

(sb!xc:defmacro %make-structure-instance-macro (dd slot-specs &rest slot-vars)
  (if (compiler-layout-ready-p (dd-name dd))
      `(truly-the ,(dd-name dd)
                  (%make-structure-instance ,dd ,slot-specs ,@slot-vars))
      ;; Non-toplevel defstructs don't have a layout at compile time,
      ;; so we need to construct the actual function at runtime -- but
      ;; we cache it at the call site, so that we don't perform quite
      ;; so horribly.
      `(let* ((cell (load-time-value (list nil)))
              (fun (car cell)))
         (if (functionp fun)
             (funcall fun ,@slot-vars)
             (funcall (setf (car cell)
                            (%make-structure-instance-allocator ,dd ,slot-specs))
                      ,@slot-vars)))))

(declaim (ftype (sfunction (defstruct-description list) function)
                %make-structure-instance-allocator))
(defun %make-structure-instance-allocator (dd slot-specs)
  (let ((vars (make-gensym-list (length slot-specs))))
    (values (compile nil
                     `(lambda (,@vars)
                        (%make-structure-instance-macro ,dd ',slot-specs ,@vars))))))

(defun %make-funcallable-structure-instance-allocator (dd slot-specs)
  (when slot-specs
    (bug "funcallable-structure-instance allocation with slots unimplemented"))
  (let ((name (dd-name dd))
        (length (dd-length dd))
        (nobject (gensym "OBJECT")))
    (values
     (compile nil `(lambda ()
                     (let ((,nobject (%make-funcallable-instance ,length)))
                       (setf (%funcallable-instance-layout ,nobject)
                             (%delayed-get-compiler-layout ,name))
                       ,nobject))))))

;;; Delay looking for compiler-layout until the constructor is being
;;; compiled, since it doesn't exist until after the EVAL-WHEN
;;; (COMPILE) stuff is compiled. (Or, in the oddball case when
;;; DEFSTRUCT is executing in a non-toplevel context, the
;;; compiler-layout still doesn't exist at compilation time, and we
;;; delay still further.)
(sb!xc:defmacro %delayed-get-compiler-layout (name)
  (let ((layout (info :type :compiler-layout name)))
    (cond (layout
           ;; ordinary case: When the DEFSTRUCT is at top level,
           ;; then EVAL-WHEN (COMPILE) stuff will have set up the
           ;; layout for us to use.
           (unless (typep (layout-info layout) 'defstruct-description)
             (error "Class is not a structure class: ~S" name))
           `,layout)
          (t
           ;; KLUDGE: In the case that DEFSTRUCT is not at top-level
           ;; the layout doesn't exist at compile time. In that case
           ;; we laboriously look it up at run time. This code will
           ;; run on every constructor call and will likely be quite
           ;; slow, so if anyone cares about performance of
           ;; non-toplevel DEFSTRUCTs, it should be rewritten to be
           ;; cleverer. -- WHN 2002-10-23
           (sb!c:compiler-notify
            "implementation limitation: ~
             Non-toplevel DEFSTRUCT constructors are slow.")
           (with-unique-names (layout)
             `(let ((,layout (info :type :compiler-layout ',name)))
                (unless (typep (layout-info ,layout) 'defstruct-description)
                  (error "Class is not a structure class: ~S" ',name))
                ,layout))))))

;;; re. %DELAYED-GET-COMPILER-LAYOUT and COMPILE-TIME-FIND-LAYOUT, above..
;;;
;;; FIXME: Perhaps both should be defined with DEFMACRO-MUNDANELY?
;;; FIXME: Do we really need both? If so, their names and implementations
;;; should probably be tweaked to be more parallel.

;;;; DEFSTRUCT-DESCRIPTION

;;; The DEFSTRUCT-DESCRIPTION structure holds compile-time information
;;; about a structure type.
;;; Its definition occurs in 'early-classoid.lisp'
(def!method print-object ((x defstruct-description) stream)
  (print-unreadable-object (x stream :type t :identity t)
    (prin1 (dd-name x) stream)))

;;; Does DD describe a structure with a class?
(defun dd-class-p (dd)
  (if (member (dd-type dd) '(structure funcallable-structure)) t nil))

(defun dd-layout-or-lose (dd)
  (compiler-layout-or-lose (dd-name dd)))

;;;; DEFSTRUCT-SLOT-DESCRIPTION

;;; A DEFSTRUCT-SLOT-DESCRIPTION holds compile-time information about
;;; a structure slot.
(def!struct (defstruct-slot-description
             (:make-load-form-fun just-dump-it-normally)
             (:conc-name dsd-)
             (:copier nil)
             #-sb-xc-host (:pure t))
  ;; name of slot
  name
  ;; its position in the implementation sequence
  (index (missing-arg) :type fixnum)
  ;; the name of the accessor function
  ;;
  ;; (CMU CL had extra complexity here ("..or NIL if this accessor has
  ;; the same name as an inherited accessor (which we don't want to
  ;; shadow)") but that behavior doesn't seem to be specified by (or
  ;; even particularly consistent with) ANSI, so it's gone in SBCL.)
  (accessor-name nil :type symbol)
  default                       ; default value expression
  (type t)                      ; declared type specifier
  (safe-p t :type boolean)      ; whether the slot is known to be
                                ; always of the specified type
  ;; If this object does not describe a raw slot, this value is T.
  ;;
  ;; If this object describes a raw slot, this value is the type of the
  ;; value that the raw slot holds.
  ;; Note: if there were more than about 5 raw types - and there aren't -
  ;; this could be made more efficient by storing either a raw-type-id
  ;; as an integer index to a vector of the raw types (presently a list,
  ;; but easily a vector), or actually just the RSD object (raw-slot-data).
  ;; Doing so would avoid some frequent re-scanning of the RSD list.
  (raw-type t :type (member t single-float double-float
                            #!+long-float long-float
                            complex-single-float complex-double-float
                            #!+long-float complex-long-float
                            sb!vm:word))
  (read-only nil :type (member t nil)))
#!-sb-fluid (declaim (freeze-type defstruct-slot-description))
(def!method print-object ((x defstruct-slot-description) stream)
  (print-unreadable-object (x stream :type t)
    (prin1 (dsd-name x) stream)))

;;;; typed (non-class) structures

;;; Return a type specifier we can use for testing :TYPE'd structures.
(defun dd-lisp-type (defstruct)
  (ecase (dd-type defstruct)
    (list 'list)
    (vector `(simple-array ,(dd-element-type defstruct) (*)))))

;;;; shared machinery for inline and out-of-line slot accessor functions

;;; Classic comment preserved for entertainment value:
;;;
;;; "A lie can travel halfway round the world while the truth is
;;; putting on its shoes." -- Mark Twain

;;;; the legendary DEFSTRUCT macro itself (both CL:DEFSTRUCT and its
;;;; close personal friend SB!XC:DEFSTRUCT)

(sb!xc:defmacro delay-defstruct-functions (name forms)
  ;; KLUDGE: If DEFSTRUCT is not at the top-level,
  ;; (typep x 'name) and similar forms can't get optimized
  ;; and produce style-warnings for unknown types.
  (if (compiler-layout-ready-p name)
      forms
      `(eval ',forms)))

(defun %defstruct-package-locks (dd)
  (let ((name (dd-name dd)))
    #+sb-xc-host (declare (ignore name))
    (with-single-package-locked-error
        (:symbol name "defining ~S as a structure"))
    (awhen (dd-predicate-name dd)
      (with-single-package-locked-error
          (:symbol it "defining ~s as a predicate for ~s structure" name)))
    (awhen (dd-copier-name dd)
      (with-single-package-locked-error
          (:symbol it "defining ~s as a copier for ~s structure" name)))
    (dolist (const (dd-constructors dd))
      (awhen (car const)
        (with-single-package-locked-error
            (:symbol it "defining ~s as a constructor for ~s structure" name))))
    (dolist (dsd (dd-slots dd))
      (awhen (dsd-accessor-name dsd)
        (with-single-package-locked-error
            (:symbol it "defining ~s as an accessor for ~s structure" name))))))

;;; shared logic for host macroexpansion for SB!XC:DEFSTRUCT and
;;; cross-compiler macroexpansion for CL:DEFSTRUCT
(defun %expander-for-defstruct (name-and-options slot-descriptions
                                expanding-into-code-for)
  ;; The host's version of this allows three choices for 'expanding-into'
  ;; up until such time as the DEFMACRO is seen (again) for DEFSTRUCT,
  ;; at which point things are ok because 'early-package' will have been
  ;; processed. The target has only one possibility.
  (aver (member expanding-into-code-for '(:target
                                          #-sb-xc :cold-target
                                          #-sb-xc :host)))
  (let* ((dd (parse-defstruct-name-and-options-and-slot-descriptions
              name-and-options slot-descriptions))
         (name (dd-name dd))
         (inherits
          (if (dd-class-p dd)
              #+sb-xc-host (!inherits-for-structure dd)
              #-sb-xc-host
              (let ((super (compiler-layout-or-lose (or (first (dd-include dd))
                                                        'structure-object))))
                (concatenate 'simple-vector
                             (layout-inherits super) (vector super)))))
         (print-method
          (when (dd-print-option dd)
            (let* ((x (sb!xc:gensym "OBJECT"))
                   (s (sb!xc:gensym "STREAM"))
                   (fname (dd-printer-fname dd))
                   (depthp (eq (dd-print-option dd) :print-function)))
              ;; Giving empty :PRINT-OBJECT or :PRINT-FUNCTION options
              ;; leaves FNAME eq to NIL. The user-level effect is
              ;; to generate a PRINT-OBJECT method specialized for the type,
              ;; implementing the default #S structure-printing behavior.
              (cond ((not fname)
                     (setf fname 'default-structure-print depthp t))
                    ((not (symbolp fname))
                     ;; Don't dump the source form into the DD constant;
                     ;; just indicate that there was an expression there.
                     (setf (dd-printer-fname dd) t)))
              `((sb!xc:defmethod print-object ((,x ,name) ,s)
                (funcall #',fname ,x ,s
                         ,@(if depthp `(*current-level-in-print*)))))))))
    `(progn
       ,@(if (dd-class-p dd)
             `(,@(when (eq expanding-into-code-for :target)
                   `((eval-when (:compile-toplevel :load-toplevel :execute)
                       ;; Note we intentionally enforce package locks and
                       ;; call %DEFSTRUCT first, and especially before
                       ;; %COMPILER-DEFSTRUCT. %DEFSTRUCT has the tests (and
                       ;; resulting CERROR) for collisions with LAYOUTs which
                       ;; already exist in the runtime. If there are any
                       ;; collisions, we want the user's response to CERROR
                       ;; to control what happens. Especially, if the user
                       ;; responds to the collision with ABORT, we don't want
                       ;; %COMPILER-DEFSTRUCT to modify the definition of the
                       ;; class.
                       (%defstruct-package-locks ',dd))))
               (%defstruct ',dd ',inherits (sb!c:source-location))
               (eval-when (:compile-toplevel :load-toplevel :execute)
                 (%compiler-defstruct ',dd ',inherits))
               ,@(unless (eq expanding-into-code-for :host)
                   `((delay-defstruct-functions
                      ,name
                      (progn ,@(awhen (copier-definition dd) (list it))
                             ,@(awhen (predicate-definition dd) (list it))
                             ,@(accessor-definitions dd)))
                ;; This must be in the same lexical environment
                     ,@(constructor-definitions dd)
                     ,@print-method
                ;; Various other operations only make sense on the target SBCL.
                     (%target-defstruct ',dd))))
            `((eval-when (:compile-toplevel :load-toplevel :execute)
                (setf (info :typed-structure :info ',name) ',dd))
              (setf (info :source-location :typed-structure ',name)
                    (sb!c:source-location))
              ,@(unless (eq expanding-into-code-for :host)
                  (append (typed-accessor-definitions dd)
                          (typed-predicate-definitions dd)
                          (typed-copier-definitions dd)
                          (constructor-definitions dd)
                          (when (dd-doc dd)
                            `((setf (fdocumentation ',(dd-name dd) 'structure)
                                    ',(dd-doc dd))))))))
       ',name)))

#+sb-xc-host
(sb!xc:defmacro defstruct (name-and-options &rest slot-descriptions)
  (%expander-for-defstruct name-and-options slot-descriptions :cold-target))

#+sb-xc
(sb!xc:defmacro defstruct (name-and-options &rest slot-descriptions)
  #!+sb-doc
  "DEFSTRUCT {Name | (Name Option*)} [Documentation] {Slot | (Slot [Default] {Key Value}*)}
   Define the structure type Name. Instances are created by MAKE-<name>,
   which takes &KEY arguments allowing initial slot values to the specified.
   A SETF'able function <name>-<slot> is defined for each slot to read and
   write slot values. <name>-p is a type predicate.

   Popular DEFSTRUCT options (see manual for others):

   (:CONSTRUCTOR Name)
   (:PREDICATE Name)
       Specify the name for the constructor or predicate.

   (:CONSTRUCTOR Name Lambda-List)
       Specify the name and arguments for a BOA constructor
       (which is more efficient when keyword syntax isn't necessary.)

   (:INCLUDE Supertype Slot-Spec*)
       Make this type a subtype of the structure type Supertype. The optional
       Slot-Specs override inherited slot options.

   Slot options:

   :TYPE Type-Spec
       Asserts that the value of this slot is always of the specified type.

   :READ-ONLY {T | NIL}
       If true, no setter function is defined for this slot."
  (%expander-for-defstruct name-and-options slot-descriptions :target))
#+sb-xc-host
(defmacro sb!xc:defstruct (name-and-options &rest slot-descriptions)
  #!+sb-doc
  "Cause information about a target structure to be built into the
  cross-compiler."
  (%expander-for-defstruct name-and-options slot-descriptions :host))

;;;; functions to generate code for various parts of DEFSTRUCT definitions

;;; First, a helper to determine whether a name names an inherited
;;; accessor.
(defun accessor-inherited-data (name defstruct)
  (assoc name (dd-inherited-accessor-alist defstruct) :test #'eq))

;;; Return a list of forms which create a predicate function for a
;;; typed DEFSTRUCT.
(defun typed-predicate-definitions (defstruct)
  (let ((name (dd-name defstruct))
        (predicate-name (dd-predicate-name defstruct))
        (argname 'x)) ; KISS: no user code appears in the DEFUN
    (when predicate-name
      (aver (dd-named defstruct))
      (let ((ltype (dd-lisp-type defstruct))
            (name-index (cdr (car (last (find-name-indices defstruct))))))
        `((defun ,predicate-name (,argname)
            (and (typep ,argname ',ltype)
                 ,(cond
                   ((subtypep ltype 'list)
                     `(do ((head (the ,ltype ,argname) (cdr head))
                           (i 0 (1+ i)))
                          ((or (not (consp head)) (= i ,name-index))
                           (and (consp head) (eq ',name (car head))))))
                   ((subtypep ltype 'vector)
                    `(and (>= (length (the ,ltype ,argname))
                           ,(dd-length defstruct))
                          (eq ',name (aref (the ,ltype ,argname) ,name-index))))
                   (t (bug "Uncatered-for lisp type in typed DEFSTRUCT: ~S."
                           ltype))))))))))

;;; Return a list of forms to create a copier function of a typed DEFSTRUCT.
(defun typed-copier-definitions (defstruct)
  (when (dd-copier-name defstruct)
    `((setf (fdefinition ',(dd-copier-name defstruct)) #'copy-seq)
      (declaim (ftype function ,(dd-copier-name defstruct))))))

;;; Return a list of function definitions for accessing and setting
;;; the slots of a typed DEFSTRUCT. The functions are proclaimed to be
;;; inline, and the types of their arguments and results are declared
;;; as well. We count on the compiler to do clever things with ELT.
(defun typed-accessor-definitions (defstruct)
  (collect ((stuff))
    (let ((ltype (dd-lisp-type defstruct)))
      (dolist (slot (dd-slots defstruct))
        (let ((name (dsd-accessor-name slot))
              (index (dsd-index slot))
              (new-value '(value))
              (slot-type `(and ,(dsd-type slot)
                               ,(dd-element-type defstruct))))
          (let ((inherited (accessor-inherited-data name defstruct)))
            (cond
              ((not inherited)
               (stuff `(declaim (inline ,name ,@(unless (dsd-read-only slot)
                                                        `((setf ,name))))))
               (stuff `(defun ,name (structure)
                        (declare (type ,ltype structure))
                        (the ,slot-type (elt structure ,index))))
               (unless (dsd-read-only slot)
                 (stuff
                  `(defun (setf ,name) (,(car new-value) structure)
                    (declare (type ,ltype structure) (type ,slot-type . ,new-value))
                    (setf (elt structure ,index) . ,new-value)))))
              ((not (= (cdr inherited) index))
               (style-warn "~@<Non-overwritten accessor ~S does not access ~
                            slot with name ~S (accessing an inherited slot ~
                            instead).~:@>" name (dsd-name slot))))))))
    (stuff)))

;;;; parsing

;;; CLHS says that
;;;   A defstruct option can be either a keyword or a list of a keyword
;;;   and arguments for that keyword; specifying the keyword by itself is
;;;   equivalent to specifying a list consisting of the keyword
;;;   and no arguments.
;;; It is unclear whether that is meant to imply that any of the keywords
;;; may be present in their atom form, or only if the grammar at the top
;;; shows the atom form does <atom> have the meaning of (<atom>).
;;; At least one other implementation accepts :NAMED as a singleton list.
;;  We take a more rigid view that the depicted grammar is exhaustive.
;;;
(defconstant-eqx +dd-option-names+
    ;; Each keyword, except :CONSTRUCTOR which may appear more than once,
    ;; and :NAMED which is trivial, and unambiguous if present more than
    ;; once, though possibly worth a style-warning.
    #(:include        ; at least 1 argument
      :initial-offset ; exactly 1 argument
      :pure           ; exactly 1 argument [nonstandard]
      :type           ; exactly 1 argument
      :conc-name      ; 0 or 1 arg
      :copier         ; "
      :predicate      ; "
      :print-function ; "
      :print-object)  ; "
  #'equalp)

;;; Parse a single DEFSTRUCT option and store the results in DD.
(defun parse-1-dd-option (option dd seen-options)
  (let* ((keyword (first option))
         (bit (position keyword +dd-option-names+))
         (args (rest option))
         (arg-p (consp args))
         (arg (if arg-p (car args)))
         (name (dd-name dd)))
    (declare (type (unsigned-byte 9) seen-options)) ; mask over DD-OPTION-NAMES
    (when bit
      (if (logbitp bit seen-options)
          (error "More than one ~S option is not allowed" keyword)
          (setf seen-options (logior seen-options (ash 1 bit))))
      (multiple-value-bind (syntax-group winp)
          (cond ; Perform checking per comment at +DD-OPTION-NAMES+.
            ((= bit 0) (values 0 (and arg-p (proper-list-p args)))) ; >1 arg
            ((< bit 4) (values 1 (and arg-p (not (cdr args))))) ; exactly 1
            (t         (values 2 (or (not args) (singleton-p args))))) ; 0 or 1
        (unless winp
          (if (proper-list-p option)
              (error "DEFSTRUCT option ~S ~[requires at least~;~
requires exactly~;accepts at most~] one argument" keyword syntax-group)
              (error "Invalid syntax in DEFSTRUCT option ~S" option)))))
    (case keyword
      (:conc-name
       ;; unlike (:predicate) and (:copier) which mean "yes" if supplied
       ;; without their argument, (:conc-name) and :conc-name mean no conc-name.
       ;; Also note a subtle difference in :conc-name "" vs :conc-name NIL.
       ;; The former re-interns each slot name into *PACKAGE* which might
       ;; not be the same as using the given name directly as an accessor.
       (setf (dd-conc-name dd) (if arg (string arg))))
      (:constructor ; takes 0 to 2 arguments.
       (destructuring-bind (&optional (cname (symbolicate "MAKE-" name))
                            lambda-list) args
         (declare (ignore lambda-list))
         (push (cons cname (cdr args)) (dd-constructors dd))))
      (:copier
       (setf (dd-copier-name dd) (if arg-p arg (symbolicate "COPY-" name))))
      (:predicate
       (setf (dd-predicate-name dd) (if arg-p arg (symbolicate name "-P"))))
      (:include
       (setf (dd-include dd) args))
      ((:print-function :print-object)
       (when (dd-print-option dd)
         (error "~S and ~S may not both be specified"
                (dd-print-option dd) keyword))
       (setf (dd-print-option dd) keyword (dd-printer-fname dd) arg))
      (:type
       (cond ((member arg '(list vector))
              (setf (dd-type dd) arg (dd-element-type dd) t))
             ((and (listp arg) (eq (first arg) 'vector))
              (destructuring-bind (elt-type) (cdr arg)
                (setf (dd-type dd) 'vector (dd-element-type dd) elt-type)))
             (t
              (error "~S is a bad :TYPE for DEFSTRUCT." arg))))
      (:named
       (error "The DEFSTRUCT option :NAMED takes no arguments."))
      (:initial-offset
       (setf (dd-offset dd) arg)) ; FIXME: disallow (:INITIAL-OFFSET NIL)
      (:pure
       (setf (dd-pure dd) arg))
      (t
       (error "unknown DEFSTRUCT option:~%  ~S" option)))
    seen-options))

;;; Given name and options, return a DD holding that info.
(defun parse-defstruct-name-and-options (name-and-options)
  (destructuring-bind (name &rest options) name-and-options
    (let ((dd (make-defstruct-description name))
          (seen-options 0))
      (dolist (option options)
        (if (eq option :named)
            (setf (dd-named dd) t)
            (setq seen-options
                  (parse-1-dd-option
                   (cond ((consp option) option)
                         ((member option
                                  '(:conc-name :constructor :copier :predicate))
                          (list option))
                         (t
                          ;; FIXME: ugly message (defstruct (s :include) a)
                          ;; saying "unrecognized" when it means "bad syntax"
                          (error "unrecognized DEFSTRUCT option: ~S" option)))
                   dd seen-options))))
      (case (dd-type dd)
        (structure
         (when (dd-offset dd)
           (error ":OFFSET can't be specified unless :TYPE is specified."))
         (unless (dd-include dd)
           ;; FIXME: It'd be cleaner to treat no-:INCLUDE as defaulting
           ;; to :INCLUDE STRUCTURE-OBJECT, and then let the general-case
           ;; (INCF (DD-LENGTH DD) (DD-LENGTH included-DD)) logic take
           ;; care of this. (Except that the :TYPE VECTOR and :TYPE
           ;; LIST cases, with their :NAMED and un-:NAMED flavors,
           ;; make that messy, alas.)
           (incf (dd-length dd))))
        (t
         ;; In case we are here, :TYPE is specified.
         (if (dd-named dd)
             ;; CLHS - "The structure can be :named only if the type SYMBOL
             ;; is a subtype of the supplied element-type."
             (multiple-value-bind (winp certainp)
                 (subtypep 'symbol (dd-element-type dd))
               (when (and (not winp) certainp)
                 (error ":NAMED option is incompatible with element type ~S"
                        (dd-element-type dd))))
             (when (dd-predicate-name dd)
               (error ":PREDICATE cannot be used with :TYPE ~
unless :NAMED is also specified.")))
         (awhen (dd-print-option dd)
           (error ":TYPE option precludes specification of ~S option" it))
         (when (dd-named dd)
           (incf (dd-length dd)))
         (let ((offset (dd-offset dd)))
           (when offset (incf (dd-length dd) offset)))))

      (flet ((option-present-p (bit-name)
               (logbitp (position bit-name +dd-option-names+) seen-options)))
        (declare (inline option-present-p))
        (when (and (not (option-present-p :predicate))
                   (or (dd-class-p dd) (dd-named dd)))
          (setf (dd-predicate-name dd) (symbolicate name "-P")))
        (unless (option-present-p :conc-name)
          (setf (dd-conc-name dd) (concatenate 'string (string name) "-")))
        (unless (option-present-p :copier)
          (setf (dd-copier-name dd) (symbolicate "COPY-" name))))
      (when (dd-include dd)
        (frob-dd-inclusion-stuff dd))

      dd)))

;;; BOA constructors is (&aux x), i.e. without the default value, the
;;; value of the slot is unspecified, but it should signal a type
;;; error only when it's accessed. safe-p slot in dsd determines
;;; whether to check the type after accessing the slot.
;;;
;;; This was performed during boa constructor creating, but the
;;; constructors are created after this information is used to inform
;;; the compiler how to treat such slots.
(defun determine-unsafe-slots (dd)
  (loop for (name lambda-list) in (dd-constructors dd)
        for &aux = (cdr (member '&aux lambda-list))
        do
        (loop with name
              for slot in &aux
              if (typecase slot
                   ((cons symbol null)
                    (setf name (car slot))
                    t)
                   (symbol (setf name slot)
                    t))
              do (let ((dsd (find name  (dd-slots dd)
                                  :key #'dsd-name
                                  :test #'eq)))
                   (when dsd
                     (setf (dsd-safe-p dsd) nil))))))

;;; Given name and options and slot descriptions (and possibly doc
;;; string at the head of slot descriptions) return a DD holding that
;;; info.
(defun parse-defstruct-name-and-options-and-slot-descriptions
    (name-and-options slot-descriptions)
  (let ((result (parse-defstruct-name-and-options (if (atom name-and-options)
                                                      (list name-and-options)
                                                      name-and-options))))
    (when (stringp (car slot-descriptions))
      (setf (dd-doc result) (pop slot-descriptions)))
    (dolist (slot-description slot-descriptions)
      (allocate-1-slot result (parse-1-dsd result slot-description)))
    (determine-unsafe-slots result)
    result))

;;;; stuff to parse slot descriptions

;;; Parse a slot description for DEFSTRUCT, add it to the description
;;; and return it. If supplied, SLOT is a pre-initialized DSD
;;; that we modify to get the new slot. This is supplied when handling
;;; included slots.
(defun parse-1-dsd (defstruct spec &optional
                    (slot (make-defstruct-slot-description :name ""
                                                           :index 0
                                                           :type t)))
  (multiple-value-bind (name default default-p type type-p read-only ro-p)
      (typecase spec
        (symbol
         (typecase spec
           ((or null (member :conc-name :constructor :copier :predicate :named))
            (warn "slot name of ~S indicates probable syntax error in DEFSTRUCT" spec))
           (keyword
            (style-warn "slot name of ~S indicates possible syntax error in DEFSTRUCT" spec)))
         spec)
        (cons
         (destructuring-bind
               (name &optional (default nil default-p)
                     &key (type nil type-p) (read-only nil ro-p))
             spec
           (when (dd-conc-name defstruct)
             ;; the warning here is useful, but in principle we cannot
             ;; distinguish between legitimate and erroneous use of
             ;; these names when :CONC-NAME is NIL.  In the common
             ;; case (CONC-NAME non-NIL), there are alternative ways
             ;; of writing code with the same effect, so a full
             ;; warning is justified.
             (typecase name
               ((member :conc-name :constructor :copier :predicate :include
                        :print-function :print-object :type :initial-offset :pure)
                (warn "slot name of ~S indicates probable syntax error in DEFSTRUCT" name))))
           (values name default default-p
                   (uncross type) type-p
                   read-only ro-p)))
        (t (error 'simple-program-error
                  :format-control "in DEFSTRUCT, ~S is not a legal slot ~
                                   description."
                  :format-arguments (list spec))))

    (when (find name (dd-slots defstruct)
                :test #'string=
                :key (lambda (x) (symbol-name (dsd-name x))))
      (error 'simple-program-error
             ;; Todo: indicate whether name is a duplicate in the directly
             ;; specified slots vs. exists in the ancestor and so should
             ;; be in the (:include ...) clause instead of where it is.
             :format-control "duplicate slot name ~S"
             :format-arguments (list name)))
    (setf (dsd-name slot) name)
    (setf (dd-slots defstruct) (nconc (dd-slots defstruct) (list slot)))

    (let ((accessor-name (if (dd-conc-name defstruct)
                             (symbolicate (dd-conc-name defstruct) name)
                             name))
          (predicate-name (dd-predicate-name defstruct)))
      (setf (dsd-accessor-name slot) accessor-name)
      (when (eql accessor-name predicate-name)
        ;; Some adventurous soul has named a slot so that its accessor
        ;; collides with the structure type predicate. ANSI doesn't
        ;; specify what to do in this case. As of 2001-09-04, Martin
        ;; Atzmueller reports that CLISP and Lispworks both give
        ;; priority to the slot accessor, so that the predicate is
        ;; overwritten. We might as well do the same (as well as
        ;; signalling a warning).
        (style-warn
         "~@<The structure accessor name ~S is the same as the name of the ~
          structure type predicate. ANSI doesn't specify what to do in ~
          this case. We'll overwrite the type predicate with the slot ~
          accessor, but you can't rely on this behavior, so it'd be wise to ~
          remove the ambiguity in your code.~@:>"
         accessor-name)
        (setf (dd-predicate-name defstruct) nil))
      ;; FIXME: It would be good to check for name collisions here, but
      ;; the easy check,
      ;;x#-sb-xc-host
      ;;x(when (and (fboundp accessor-name)
      ;;x           (not (accessor-inherited-data accessor-name defstruct)))
      ;;x  (style-warn "redefining ~/sb-impl::print-symbol-with-prefix/ ~
      ;;                in DEFSTRUCT" accessor-name)))
      ;; which was done until sbcl-0.8.11.18 or so, is wrong: it causes
      ;; a warning at MACROEXPAND time, when instead the warning should
      ;; occur not just because the code was constructed, but because it
      ;; is actually compiled or loaded.
      )

    (when default-p
      (setf (dsd-default slot) default))
    (when type-p
      (setf (dsd-type slot)
            (if (eq (dsd-type slot) t)
                type
                `(and ,(dsd-type slot) ,type))))
    (when ro-p
      (if read-only
          (setf (dsd-read-only slot) t)
          (when (dsd-read-only slot)
            (error "~@<The slot ~S is :READ-ONLY in superclass, and so must ~
                       be :READ-ONLY in subclass.~:@>"
                   (dsd-name slot)))))
    slot))

;;; When a value of type TYPE is stored in a structure, should it be
;;; stored in a raw slot?  Return the matching RAW-SLOT-DATA structure
;; if TYPE should be stored in a raw slot, or NIL if not.
(defun structure-raw-slot-data (type)
  (multiple-value-bind (fixnum? fixnum-certain?)
      (sb!xc:subtypep type 'fixnum)
    ;; (The extra test for FIXNUM-CERTAIN? here is intended for
    ;; bootstrapping the system. In particular, in sbcl-0.6.2, we set up
    ;; LAYOUT before FIXNUM is defined, and so could bogusly end up
    ;; putting INDEX-typed values into raw slots if we didn't test
    ;; FIXNUM-CERTAIN?.)
    (if (or fixnum? (not fixnum-certain?))
        nil
        (dolist (data *raw-slot-data-list*)
          (when (sb!xc:subtypep type (raw-slot-data-raw-type data))
            (return data))))))

;;; Allocate storage for a DSD in DD. This is where we decide whether
;;; a slot is raw or not. Raw objects are aligned on the unit of their size.
(defun allocate-1-slot (dd dsd)
  (let ((rsd (if (eq (dd-type dd) 'structure)
                 (structure-raw-slot-data (dsd-type dsd))
                 nil)))
    (cond ((null rsd)
           (setf (dsd-index dsd) (dd-length dd))
           (incf (dd-length dd)))
          (t
           (setf (dsd-raw-type dsd) (raw-slot-data-raw-type rsd))
           (let ((words (raw-slot-data-n-words rsd))
                 (alignment (raw-slot-data-alignment rsd)))
             #!-interleaved-raw-slots
             (let ((off (rem (dd-raw-length dd) alignment)))
               (unless (zerop off)
                 (incf (dd-raw-length dd) (- alignment off)))
               (setf (dsd-index dsd) (dd-raw-length dd))
               (incf (dd-raw-length dd) words))
             #!+interleaved-raw-slots
             (let ((len (dd-length dd)))
               (setf (dd-length dd)
                     ;; this formula works but can it be made less unclear?
                     (- len (nth-value 1 (ceiling (1- len) alignment))))
               (setf (dsd-index dsd) (dd-length dd))
               (incf (dd-length dd) words))))))
  (values))

(defun typed-structure-info-or-lose (name)
  (or (info :typed-structure :info name)
      (error ":TYPE'd DEFSTRUCT ~S not found for inclusion." name)))

;;; Process any included slots pretty much like they were specified.
;;; Also inherit various other attributes.
(defun frob-dd-inclusion-stuff (dd)
  (destructuring-bind (included-name &rest modified-slots) (dd-include dd)
    (let* ((type (dd-type dd))
           (included-structure
            (if (dd-class-p dd)
                (layout-info (compiler-layout-or-lose included-name))
                (typed-structure-info-or-lose included-name))))

      ;; checks on legality
      (unless (and (eq type (dd-type included-structure))
                   (type= (specifier-type (dd-element-type included-structure))
                          (specifier-type (dd-element-type dd))))
        (error ":TYPE option mismatch between structures ~S and ~S"
               (dd-name dd) included-name))
      (let ((included-classoid (find-classoid included-name nil)))
        (when included-classoid
          ;; It's not particularly well-defined to :INCLUDE any of the
          ;; CMU CL INSTANCE weirdosities like CONDITION or
          ;; GENERIC-FUNCTION, and it's certainly not ANSI-compliant.
          (let* ((included-layout (classoid-layout included-classoid))
                 (included-dd (layout-info included-layout)))
            (when (dd-alternate-metaclass included-dd)
              (error "can't :INCLUDE class ~S (has alternate metaclass)"
                     included-name)))))

      ;; A few more sanity checks: every allegedly modified slot exists
      ;; and no name appears more than once.
      (flet ((included-slot-name (slot-desc)
               (if (atom slot-desc) slot-desc (car slot-desc))))
        (mapl (lambda (slots &aux (name (included-slot-name (car slots))))
                (unless (find name (dd-slots included-structure)
                              :test #'string= :key #'dsd-name)
                  (error 'simple-program-error
                         :format-control "slot name ~S not present in included structure"
                         :format-arguments (list name)))
                (when (find name (cdr slots)
                            :test #'string= :key #'included-slot-name)
                  (error 'simple-program-error
                         :format-control "included slot name ~S specified more than once"
                         :format-arguments (list name))))
              modified-slots))

      (incf (dd-length dd) (dd-length included-structure))
      (when (dd-class-p dd)
        (when (eq (dd-pure dd) :unspecified)
          (setf (dd-pure dd) (dd-pure included-structure)))
        #!-interleaved-raw-slots
        (setf (dd-raw-length dd) (dd-raw-length included-structure)))

      (setf (dd-inherited-accessor-alist dd)
            (dd-inherited-accessor-alist included-structure))
      (dolist (included-slot (dd-slots included-structure))
        (let* ((included-name (dsd-name included-slot))
               (modified (or (find included-name modified-slots
                                   :key (lambda (x) (if (atom x) x (car x)))
                                   :test #'string=)
                             `(,included-name))))
          ;; We stash away an alist of accessors to parents' slots
          ;; that have already been created to avoid conflicts later
          ;; so that structures with :INCLUDE and :CONC-NAME (and
          ;; other edge cases) can work as specified.
          (when (dsd-accessor-name included-slot)
            ;; the "oldest" (i.e. highest up the tree of inheritance)
            ;; will prevail, so don't push new ones on if they
            ;; conflict.
            (pushnew (cons (dsd-accessor-name included-slot)
                           (dsd-index included-slot))
                     (dd-inherited-accessor-alist dd)
                     :test #'eq :key #'car))
          (let ((new-slot (parse-1-dsd dd
                                       modified
                                       (copy-structure included-slot))))
            (when (and (neq (dsd-type new-slot) (dsd-type included-slot))
                       (not (sb!xc:subtypep (dsd-type included-slot)
                                            (dsd-type new-slot)))
                       (dsd-safe-p included-slot))
              (setf (dsd-safe-p new-slot) nil)
              ;; XXX: notify?
              )))))))

;;;; various helper functions for setting up DEFSTRUCTs

;;; This function is called at macroexpand time to compute the INHERITS
;;; vector for a structure type definition.
;;; The cross-compiler is allowed to magically compute LAYOUT-INHERITS.
(defun !inherits-for-structure (info)
  (declare (type defstruct-description info))
  (let* ((include (dd-include info))
         (superclass-opt (dd-alternate-metaclass info))
         (super
          (if include
              (compiler-layout-or-lose (first include))
              (classoid-layout (find-classoid
                                (or (first superclass-opt)
                                    'structure-object))))))
    (case (dd-name info)
      ((ansi-stream)
       ;; STREAM is an abstract class and you can't :include it,
       ;; so the inheritance has to be hardcoded.
       (concatenate 'simple-vector
                    (layout-inherits super)
                    (vector super (classoid-layout (find-classoid 'stream)))))
      ((fd-stream) ; Similarly, FILE-STREAM is abstract
       (concatenate 'simple-vector
                    (layout-inherits super)
                    (vector super
                            (classoid-layout (find-classoid 'file-stream)))))
      ((sb!impl::string-input-stream ; etc
        sb!impl::string-output-stream
        sb!impl::fill-pointer-output-stream)
       (concatenate 'simple-vector
                    (layout-inherits super)
                    (vector super
                            (classoid-layout (find-classoid 'string-stream)))))
      (t (concatenate 'simple-vector
                      (layout-inherits super)
                      (vector super))))))

;;; Do miscellaneous (LOAD EVAL) time actions for the structure
;;; described by DD. Create the class and LAYOUT, checking for
;;; incompatible redefinition.
(defun %defstruct (dd inherits source-location)
  (declare (type defstruct-description dd))

  ;; We set up LAYOUTs even in the cross-compilation host.
  (multiple-value-bind (classoid layout old-layout)
      (ensure-structure-class dd inherits "current" "new")
    (cond ((not old-layout)
           (unless (eq (classoid-layout classoid) layout)
             (register-layout layout)))
          (t
           (%redefine-defstruct classoid old-layout layout)
           (let ((old-dd (layout-info old-layout)))
             (when (defstruct-description-p old-dd)
               (dolist (slot (dd-slots old-dd))
                 (fmakunbound (dsd-accessor-name slot))
                 (unless (dsd-read-only slot)
                   (fmakunbound `(setf ,(dsd-accessor-name slot)))))))
           (setq layout (classoid-layout classoid))))
    (setf (find-classoid (dd-name dd)) classoid)

    (sb!c:with-source-location (source-location)
      (setf (layout-source-location layout) source-location))))


;;; Return a form describing the writable place used for this slot
;;; in the instance named INSTANCE-NAME.
(defun %accessor-place-form (dd dsd instance-name)
  (let (;; the operator that we'll use to access a typed slot
        (ref (ecase (dd-type dd)
               (structure '%instance-ref)
               (list 'nth-but-with-sane-arg-order)
               (vector 'aref)))
        (raw-type (dsd-raw-type dsd)))
    (if (eq raw-type t) ; if not raw slot
        `(,ref ,instance-name ,(dsd-index dsd))
        `(,(raw-slot-data-accessor-name (raw-slot-data-or-lose raw-type))
          ,instance-name ,(dsd-index dsd)))))

;;; Return the transformation of conceptual FUNCTION (either :READ or :WRITE)
;;; applied to ARGS, given SLOT-KEY which is a cons of a DD and a DSD.
;;; Return NIL on failure.
(defun slot-access-transform (function args slot-key)
  (when (consp args) ; need at least one arg
    (let* ((dd (car slot-key))
           (dsd (cdr slot-key))
           ;; optimistically compute PLACE before checking length of ARGS
           ;; because we expect success, and this unifies the two cases.
           ;; :WRITE has the arg order of (SETF fn), i.e. newval is first,
           ;; so if more than one arg exists, take the second as the INSTANCE.
           (place
            (%accessor-place-form
             dd dsd `(the ,(dd-name dd)
                          ,(car (if (consp (cdr args)) (cdr args) args)))))
           (type-spec (dsd-type dsd)))
      (ecase function
        (:read
         (when (singleton-p args)
           (if (eq type-spec t)
               place
               `(,(if (dsd-safe-p dsd) 'truly-the 'the) ,type-spec ,place))))
        (:write
         (when (singleton-p (cdr args))
           (once-only ((new (first args)))
             ;; instance setters take newval last.
             `(,(info :setf :inverse (car place)) ,@(cdr place)
               ,(if (eq type-spec t) new `(the ,type-spec ,new))))))))))

;;; Return a LAMBDA form which can be used to set a slot
(defun slot-setter-lambda-form (dd dsd)
  `(lambda (newval instance)
     ,(slot-access-transform :write '(newval instance) (cons dd dsd))))

;;; Blow away all the compiler info for the structure CLASS. Iterate
;;; over this type, clearing the compiler structure type info, and
;;; undefining all the associated functions.  If SUBCLASSES-P, also do
;;; the same for subclasses.  FIXME: maybe rename UNDEFINE-FUN-NAME to
;;; UNDECLARE-FUNCTION-NAME?
(defun undeclare-structure (classoid subclasses-p)
  (let ((info (layout-info (classoid-layout classoid))))
    (when (defstruct-description-p info)
      (let ((type (dd-name info)))
        (clear-info :type :compiler-layout type)
        (undefine-fun-name (dd-copier-name info))
        (undefine-fun-name (dd-predicate-name info))
        (dolist (slot (dd-slots info))
          (let ((fun (dsd-accessor-name slot)))
            (unless (accessor-inherited-data fun info)
              (undefine-fun-name fun)
              (unless (dsd-read-only slot)
                (undefine-fun-name `(setf ,fun)))))))
      ;; Clear out the SPECIFIER-TYPE cache so that subsequent
      ;; references are unknown types.
      (values-specifier-type-cache-clear)))
  (when subclasses-p
    (let ((subclasses (classoid-subclasses classoid)))
      (when subclasses
        (collect ((subs))
          (dohash ((classoid layout)
                   subclasses
                   :locked t)
            (declare (ignore layout))
            (undeclare-structure classoid nil)
            (subs (classoid-proper-name classoid)))
          ;; Is it really necessary to warn about
          ;; undeclaring functions for subclasses?
          (when (subs)
            (warn "undeclaring functions for old subclasses ~
                               of ~S:~%  ~S"
                  (classoid-name classoid)
                  (subs))))))))

;;; core compile-time setup of any class with a LAYOUT, used even by
;;; !DEFSTRUCT-WITH-ALTERNATE-METACLASS weirdosities
(defun %compiler-set-up-layout (dd
                                &optional
                                ;; Several special cases
                                ;; (STRUCTURE-OBJECT itself, and
                                ;; structures with alternate
                                ;; metaclasses) call this function
                                ;; directly, and they're all at the
                                ;; base of the instance class
                                ;; structure, so this is a handy
                                ;; default.  (But note
                                ;; FUNCALLABLE-STRUCTUREs need
                                ;; assistance here)
                                (inherits (vector (find-layout t))))

  (multiple-value-bind (classoid layout old-layout)
      (multiple-value-bind (clayout clayout-p)
          (info :type :compiler-layout (dd-name dd))
        (ensure-structure-class dd
                                inherits
                                (if clayout-p
                                    "The most recently compiled"
                                    "The current")
                                "the most recently loaded"
                                :compiler-layout clayout))
    (cond (old-layout
           (undeclare-structure (layout-classoid old-layout)
                                (and (classoid-subclasses classoid)
                                     (not (eq layout old-layout))))
           (setf (layout-invalid layout) nil)
           ;; FIXME: it might be polite to hold onto old-layout and
           ;; restore it at the end of the file.  -- RMK 2008-09-19
           ;; (International Talk Like a Pirate Day).
           (warn "~@<Clobbering the compiler's idea of the layout of ~A.~:@>"
                 classoid))
          (t
           (unless (eq (classoid-layout classoid) layout)
             (register-layout layout :invalidate nil))
           (setf (find-classoid (dd-name dd)) classoid)))

    ;; At this point the class should be set up in the INFO database.
    ;; But the logic that enforces this is a little tangled and
    ;; scattered, so it's not obvious, so let's check.
    (aver (find-classoid (dd-name dd) nil))

    (setf (info :type :compiler-layout (dd-name dd)) layout))
  (values))

;;; Do (COMPILE LOAD EVAL)-time actions for the normal (not
;;; ALTERNATE-LAYOUT) DEFSTRUCT described by DD.
;;; This includes generation of a style-warning about previously compiled
;;; calls to the accessors and/or predicate that weren't inlined.
(defun %compiler-defstruct (dd inherits)
  (declare (type defstruct-description dd))

  (aver (dd-class-p dd)) ; LIST and VECTOR representation are not allowed
  (let ((check-inlining
         ;; Why use the secondary result of INFO, not the primary?
         ;; Because when DEFSTRUCT is evaluated, not via the file-compiler,
         ;; the first thing to happen is %DEFSTRUCT, which sets up FIND-CLASS.
         ;; Due to :COMPILER-LAYOUT's defaulting expression in globaldb,
         ;; it has a value - the layout of the classoid - that we don't want.
         ;; Also, since structures are technically not redefineable,
         ;; I don't worry about failure to inline a function that was
         ;; formerly not known as an accessor but now is.
         (null (nth-value 1 (info :type :compiler-layout (dd-name dd)))))
        (fnames))
    (%compiler-set-up-layout dd inherits)

    (awhen (dd-copier-name dd)
      (let ((dtype (dd-name dd)))
        (sb!xc:proclaim `(ftype (sfunction (,dtype) ,dtype) ,it))))

    (let ((predicate-name (dd-predicate-name dd)))
      (when predicate-name
        (when check-inlining
          (push predicate-name fnames))
        (setf (info :function :source-transform predicate-name)
              (cons dd :predicate))))

    (dolist (dsd (dd-slots dd))
      (let ((accessor-name (dsd-accessor-name dsd)))
        ;; Why this WHEN guard here, if there is neither a standards-specified
        ;; nor implementation-specific way to skip defining an accessor? Dunno.
        ;; And furthermore, by ignoring a package lock, it's possible to name
        ;; an accessor NIL: (defstruct (x (:conc-name "N")) IL)
        ;; making this test kinda bogus in two different ways.
        (when accessor-name
          (let ((inherited (accessor-inherited-data accessor-name dd)))
            (cond
              ((not inherited)
               (let ((writer `(setf ,accessor-name))
                     (slot-key (cons dd dsd)))
                 (when check-inlining
                   (push accessor-name fnames))
                 (setf (info :function :source-transform accessor-name)
                       slot-key)
                 (unless (dsd-read-only dsd)
                   (when check-inlining
                     (push writer fnames))
                   (setf (info :function :source-transform writer) slot-key))))
              ((not (= (cdr inherited) (dsd-index dsd)))
               (style-warn "~@<Non-overwritten accessor ~S does not access ~
                            slot with name ~S (accessing an inherited slot ~
                            instead).~:@>"
                           accessor-name
                           (dsd-name dsd))))))))

    (awhen (remove-if-not #'sb!c::emitted-full-call-count fnames)
      (sb!c:compiler-style-warn
       'sb!c:inlining-dependency-failure
       ;; This message omits the http://en.wikipedia.org/wiki/Serial_comma
       :format-control
       (!uncross-format-control
        "~@<Previously compiled call~P to ~
~{~/sb!impl:print-symbol-with-prefix/~^~#[~; and~:;,~] ~} ~
could not be inlined because the structure definition for ~
~/sb!impl:print-symbol-with-prefix/ was not yet seen. To avoid this warning, ~
DEFSTRUCT should precede references to the affected functions, ~
or they must be declared locally notinline at each call site.~@:>")
       :format-arguments (list (length it) (nreverse it) (dd-name dd))))))

;;;; redefinition stuff

;;; Compare the slots of OLD and NEW, returning 3 lists of slot names:
;;;   1. Slots which have moved,
;;;   2. Slots whose type has changed,
;;;   3. Deleted slots.
(defun compare-slots (old new)
  (let* ((oslots (dd-slots old))
         (nslots (dd-slots new))
         (onames (mapcar #'dsd-name oslots))
         (nnames (mapcar #'dsd-name nslots)))
    (collect ((moved)
              (retyped))
      (dolist (name (intersection onames nnames))
        (let ((os (find name oslots :key #'dsd-name :test #'string=))
              (ns (find name nslots :key #'dsd-name :test #'string=)))
          (unless (sb!xc:subtypep (dsd-type ns) (dsd-type os))
            (retyped name))
          (unless (and (= (dsd-index os) (dsd-index ns))
                       (eq (dsd-raw-type os) (dsd-raw-type ns)))
            (moved name))))
      (values (moved)
              (retyped)
              (set-difference onames nnames :test #'string=)))))

;;; If we are redefining a structure with different slots than in the
;;; currently loaded version, give a warning and return true.
(defun redefine-structure-warning (classoid old new)
  (declare (type defstruct-description old new)
           (type classoid classoid)
           (ignore classoid))
  (let ((name (dd-name new)))
    (multiple-value-bind (moved retyped deleted) (compare-slots old new)
      (when (or moved retyped deleted)
        (warn
         "incompatibly redefining slots of structure class ~S~@
          Make sure any uses of affected accessors are recompiled:~@
          ~@[  These slots were moved to new positions:~%    ~S~%~]~
          ~@[  These slots have new incompatible types:~%    ~S~%~]~
          ~@[  These slots were deleted:~%    ~S~%~]"
         name moved retyped deleted)
        t))))

;;; This function is called when we are incompatibly redefining a
;;; structure CLASS to have the specified NEW-LAYOUT. We signal an
;;; error with some proceed options and return the layout that should
;;; be used.
(defun %redefine-defstruct (classoid old-layout new-layout)
  (declare (type classoid classoid)
           (type layout old-layout new-layout))
  (let ((name (classoid-proper-name classoid)))
    (restart-case
        (error "~@<attempt to redefine the ~S class ~S incompatibly with the current definition~:@>"
               'structure-object
               name)
      (continue ()
       :report (lambda (s)
                 (format s
                         "~@<Use the new definition of ~S, invalidating ~
                          already-loaded code and instances.~@:>"
                         name))
       (register-layout new-layout))
      (recklessly-continue ()
       :report (lambda (s)
                 (format s
                         "~@<Use the new definition of ~S as if it were ~
                          compatible, allowing old accessors to use new ~
                          instances and allowing new accessors to use old ~
                          instances.~@:>"
                         name))
       ;; classic CMU CL warning: "Any old ~S instances will be in a bad way.
       ;; I hope you know what you're doing..."
       (register-layout new-layout
                        :invalidate nil
                        :destruct-layout old-layout))
      (clobber-it ()
       ;; FIXME: deprecated 2002-10-16, and since it's only interactive
       ;; hackery instead of a supported feature, can probably be deleted
       ;; in early 2003
       :report "(deprecated synonym for RECKLESSLY-CONTINUE)"
       (register-layout new-layout
                        :invalidate nil
                        :destruct-layout old-layout))))
  (values))

(declaim (inline dd-layout-length))
(defun dd-layout-length (dd)
  (+ (dd-length dd) #!-interleaved-raw-slots (dd-raw-length dd)))

(declaim (ftype (sfunction (defstruct-description) index) dd-instance-length))
(defun dd-instance-length (dd)
  ;; Make sure the object ends at a two-word boundary.  Note that this does
  ;; not affect the amount of memory used, since the allocator would add the
  ;; same padding anyway.  However, raw slots are indexed from the length of
  ;; the object as indicated in the header, so the pad word needs to be
  ;; included in that length to guarantee proper alignment of raw double float
  ;; slots, necessary for (at least) the SPARC backend.
  ;; On backends with interleaved raw slots, the convention of having the
  ;; header possibly "lie" about an extra word is more of a bug than a feature.
  ;; Because the structure base is aligned, double-word raw slots are properly
  ;; aligned, and won't change alignment in descendant object types. It would
  ;; be correct to store the true instance length even though GC preserves
  ;; the extra data word (as it does for odd-length SIMPLE-VECTOR), treating
  ;; the total physical length as rounded-to-even. But having two different
  ;; conventions would be even more unnecessarily confusing, so we use
  ;; the not-sensible convention even when it does not make sense.
  (logior (dd-layout-length dd) 1))

(defun dd-bitmap (dd)
  ;; The bitmap stores a 1 for each untagged word,
  ;; including any internal padding words for alignment.
  ;; The 0th bit is initialized to 0 because the LAYOUT is a tagged
  ;; slot that is not present in DD-SLOTS.
  ;; All other bits start as 1 and are cleared if the word is tagged.
  ;; A final padding word, if any, is regarded as tagged.
  (let ((bitmap (ldb (byte (dd-length dd) 0)
                     (ash -1 sb!vm:instance-data-start))))
    (dolist (slot (dd-slots dd) bitmap)
      (when (eql t (dsd-raw-type slot))
        (setf (ldb (byte 1 (dsd-index slot)) bitmap) 0)))))

;;; This is called when we are about to define a structure class. It
;;; returns a (possibly new) class object and the layout which should
;;; be used for the new definition (may be the current layout, and
;;; also might be an uninstalled forward referenced layout.) The third
;;; value is true if this is an incompatible redefinition, in which
;;; case it is the old layout.
(defun ensure-structure-class (info inherits old-context new-context
                                    &key compiler-layout)
  (declare (type defstruct-description info))
  (multiple-value-bind (class old-layout)
      (multiple-value-bind (class constructor)
          (acond ((cdr (dd-alternate-metaclass info))
                  (values (first it) (second it)))
                 (t
                  (values 'structure-classoid 'make-structure-classoid)))
        (insured-find-classoid (dd-name info)
                               (if (eq class 'structure-classoid)
                                   (lambda (x)
                                     (sb!xc:typep x 'structure-classoid))
                                   (lambda (x)
                                     (sb!xc:typep x (classoid-name (find-classoid class)))))
                               (fdefinition constructor)))
    (setf (classoid-direct-superclasses class)
          (case (dd-name info)
            ((ansi-stream
              fd-stream
              sb!impl::string-input-stream sb!impl::string-output-stream
              sb!impl::fill-pointer-output-stream)
             (list (layout-classoid (svref inherits (1- (length inherits))))
                   (layout-classoid (svref inherits (- (length inherits) 2)))))
            (t
             (list (layout-classoid
                    (svref inherits (1- (length inherits))))))))
    (let* ((old-layout (or compiler-layout old-layout))
           (new-layout
            (when (or (not old-layout) *type-system-initialized*)
              (make-layout :classoid class
                           :inherits inherits
                           :depthoid (length inherits)
                           :length (dd-layout-length info)
                           :info info . #!-interleaved-raw-slots
                                        (:n-untagged-slots (dd-raw-length info))
                                        #!+interleaved-raw-slots
                                        (:untagged-bitmap (dd-bitmap info))))))
      (cond
       ((not old-layout)
        (values class new-layout nil))
       ((not new-layout)
        ;; The assignment of INFO here can almost be deleted,
        ;; except for a few magical types that don't d.t.r.t. in cold-init:
        ;;  STRUCTURE-OBJECT, CONDITION, ALIEN-VALUE, INTERPRETED-FUNCTION
        (setf (layout-info old-layout) info)
        (values class old-layout nil))
       (;; This clause corresponds to an assertion in REDEFINE-LAYOUT-WARNING
        ;; of classic CMU CL. I moved it out to here because it was only
        ;; exercised in this code path anyway. -- WHN 19990510
        (not (eq (layout-classoid new-layout) (layout-classoid old-layout)))
        (error "shouldn't happen: weird state of OLD-LAYOUT?"))
       ((redefine-layout-warning old-context
                                 old-layout
                                 new-context
                                 (layout-length new-layout)
                                 (layout-inherits new-layout)
                                 (layout-depthoid new-layout)
                                 (layout-raw-slot-metadata new-layout))
        (values class new-layout old-layout))
       (t
        (let ((old-info (layout-info old-layout)))
          (if old-info
             (cond ((redefine-structure-warning class old-info info)
                    (values class new-layout old-layout))
                   (t
                    (setf (layout-info old-layout) info)
                    (values class old-layout nil)))
             (progn
               (setf (layout-info old-layout) info)
               (values class old-layout nil)))))))))

;;; Return a list of pairs (name . index). Used for :TYPE'd
;;; constructors to find all the names that we have to splice in &
;;; where. Note that these types don't have a layout, so we can't look
;;; at LAYOUT-INHERITS.
(defun find-name-indices (defstruct)
  (collect ((res))
    (let ((infos ()))
      (do ((info defstruct
                 (typed-structure-info-or-lose (first (dd-include info)))))
          ((not (dd-include info))
           (push info infos))
        (push info infos))

      (let ((i 0))
        (dolist (info infos)
          (incf i (or (dd-offset info) 0))
          (when (dd-named info)
            (res (cons (dd-name info) i)))
          (setq i (dd-length info)))))

    (res)))

;;; These functions are called to actually make a constructor after we
;;; have processed the arglist. The correct variant (according to the
;;; DD-TYPE) should be called. The function is defined with the
;;; specified name and arglist. VARS and TYPES are used for argument
;;; type declarations. VALUES are the values for the slots (in order.)
;;;
;;; This is split three ways because:
;;;   * LIST & VECTOR structures need "name" symbols stuck in at
;;;     various weird places, whereas STRUCTURE structures have
;;;     a LAYOUT slot.
;;;   * We really want to use LIST to make list structures, instead of
;;;     MAKE-LIST/(SETF ELT). (We can't in general use VECTOR in an
;;;     analogous way, since VECTOR makes a SIMPLE-VECTOR and vector-typed
;;;     structures can have arbitrary subtypes of VECTOR, not necessarily
;;;     SIMPLE-VECTOR.)
;;;   * STRUCTURE structures can have raw slots that must also be
;;;     allocated and indirectly referenced.
(defun create-vector-constructor (dd cons-name arglist ftype-arglist decls values)
  (let ((temp (gensym))
        (etype (dd-element-type dd))
        (len (dd-length dd)))
    (values
     `(defun ,cons-name ,arglist
        ,@(when decls `((declare ,@decls)))
        (let ((,temp (make-array ,len :element-type ',etype)))
          ,@(mapcar (lambda (x)
                      `(setf (aref ,temp ,(cdr x))  ',(car x)))
                    (find-name-indices dd))
          ,@(mapcar (lambda (dsd value)
                      (unless (eq value '.do-not-initialize-slot.)
                        `(setf (aref ,temp ,(dsd-index dsd)) ,value)))
                    (dd-slots dd) values)
          ,temp))
     `(sfunction ,ftype-arglist (simple-array ,etype (,len))))))
(defun create-list-constructor (dd cons-name arglist ftype-arglist decls values)
  (let ((vals (make-list (dd-length dd) :initial-element nil)))
    (dolist (x (find-name-indices dd))
      (setf (elt vals (cdr x)) `',(car x)))
    (loop for dsd in (dd-slots dd) and val in values do
      (setf (elt vals (dsd-index dsd))
            (if (eq val '.do-not-initialize-slot.) 0 val)))
    (values
     `(defun ,cons-name ,arglist
        ,@(when decls `((declare ,@decls)))
        (list ,@vals))
     `(sfunction ,ftype-arglist list))))
(defun create-structure-constructor (dd cons-name arglist ftype-arglist decls values)
  (values
   ;; The difference between the two implementations here is that on all
   ;; platforms we don't have the appropriate RAW-INSTANCE-INIT VOPS, which
   ;; must be able to deal with immediate values as well -- unlike
   ;; RAW-INSTANCE-SET VOPs, which never end up seeing immediate values. With
   ;; some additional cleverness we might manage without them and just a single
   ;; implementation here, though -- figure out a way to ensure that on those
   ;; platforms we always still get a non-immediate TN in every case...
   ;;
   ;; Until someone does that, this means that instances with raw slots can be
   ;; DX allocated only on platforms with those additional VOPs.
   #!+raw-instance-init-vops
   (let* ((slot-values nil)
          (slot-specs
           (mapcan (lambda (dsd value)
                     (unless (eq value '.do-not-initialize-slot.)
                       (push value slot-values)
                       (list (list* :slot (dsd-raw-type dsd) (dsd-index dsd)))))
                   (dd-slots dd)
                   values)))
     `(defun ,cons-name ,arglist
        ,@(when decls `((declare ,@decls)))
        (%make-structure-instance-macro ,dd ',slot-specs ,@(reverse slot-values))))
   #!-raw-instance-init-vops
   (let ((instance (gensym "INSTANCE")) slot-values slot-specs raw-slots raw-values)
     (mapc (lambda (dsd value)
             (unless (eq value '.do-not-initialize-slot.)
               (let ((raw-type (dsd-raw-type dsd)))
                 (cond ((eq t raw-type)
                        (push value slot-values)
                        (push (list* :slot raw-type (dsd-index dsd)) slot-specs))
                       (t
                        (push value raw-values)
                        (push dsd raw-slots))))))
           (dd-slots dd)
           values)
     `(defun ,cons-name ,arglist
        ,@(when decls`((declare ,@decls)))
        ,(if raw-slots
             `(let ((,instance (%make-structure-instance-macro ,dd ',slot-specs ,@slot-values)))
                ,@(mapcar (lambda (dsd value)
                            ;; (Note that we can't in general use the
                            ;; ordinary named slot setter function here
                            ;; because the slot might be :READ-ONLY, so we
                            ;; whip up new LAMBDA representations of slot
                            ;; setters for the occasion.)
                            `(,(slot-setter-lambda-form dd dsd) ,value ,instance))
                          raw-slots
                          raw-values)
                ,instance)
             `(%make-structure-instance-macro ,dd ',slot-specs ,@slot-values))))
   `(sfunction ,ftype-arglist ,(dd-name dd))))

;;; Create a default (non-BOA) keyword constructor.
(defun create-keyword-constructor (defstruct creator)
  (declare (type function creator))
  (collect ((arglist (list '&key))
            (vals)
            (decls)
            (ftype-args))
    (let ((int-type (if (eq 'vector (dd-type defstruct))
                        (dd-element-type defstruct)
                        t)))
      (dolist (slot (dd-slots defstruct))
        (let* ((name (dsd-name slot))
               (dum (copy-symbol name))
               (keyword (keywordicate name))
               (specfied-type `(and ,int-type ,(dsd-type slot)))
               ;; Canonicalize the type for a prettier macro-expansion
               ;; but leave it as is if there is a conflict.
               (type (or (type-specifier (specifier-type specfied-type))
                         specfied-type)))
          (arglist `((,keyword ,dum) ,(dsd-default slot)))
          (vals dum)
          ;; KLUDGE: we need a separate type declaration for for
          ;; keyword arguments, since default values bypass the
          ;; checking provided by the FTYPE.
          (unless (eq t type)
            (decls `(type ,type ,dum)))
          (ftype-args `(,keyword ,type)))))
    (funcall creator
             defstruct (dd-default-constructor defstruct)
             (arglist) `(&key ,@(ftype-args)) (decls) (vals))))

;;; Given a structure and a BOA constructor spec, call CREATOR with
;;; the appropriate args to make a constructor.
(defun create-boa-constructor (defstruct boa creator)
  (declare (type function creator))
  (multiple-value-bind (llks req opt rest keys aux)
      (parse-lambda-list (second boa)
                         :accept
                         (lambda-list-keyword-mask
                            '(&optional &rest &key &allow-other-keys &aux)))
    (collect ((arglist)
              (vars)
              (skipped-vars)
              (ftype-args)
              (decls))
      (let ((int-type (if (eq 'vector (dd-type defstruct))
                          (dd-element-type defstruct)
                          t)))
        (labels ((get-slot (name)
                   (let* ((res (find name (dd-slots defstruct)
                                    :test #'string=
                                    :key #'dsd-name))
                          (type (type-specifier
                                 (specifier-type
                                  `(and ,int-type ,(if res
                                                       (dsd-type res)
                                                       t))))))
                     (values type (when res (dsd-default res)))))
                 (do-default (arg &optional keyp)
                   (multiple-value-bind (type default) (get-slot arg)
                     (arglist `(,arg ,default))
                     (vars arg)
                     (if keyp
                         (arg-type type (keywordicate arg) arg)
                         (arg-type type))))
                 (arg-type (type &optional key var)
                   (cond (key
                          ;; KLUDGE: see comment in CREATE-KEYWORD-CONSTRUCTOR.
                          (unless (eq t type)
                            (decls `(type ,type ,var)))
                          (ftype-args `(,key ,type)))
                         (t
                          (ftype-args type)))))
          (dolist (arg req)
            (arglist arg)
            (vars arg)
            (arg-type (get-slot arg)))

          (when opt
            (arglist '&optional)
            (ftype-args '&optional)
            (dolist (arg opt)
              (cond ((consp arg)
                     (destructuring-bind
                           ;; FIXME: this shares some logic (though not
                           ;; code) with the &key case below (and it
                           ;; looks confusing) -- factor out the logic
                           ;; if possible. - CSR, 2002-04-19
                           (name
                            &optional
                            (def (nth-value 1 (get-slot name)))
                            (supplied-test nil supplied-test-p))
                         arg
                       (arglist `(,name ,def ,@(if supplied-test-p `(,supplied-test) nil)))
                       (vars name)
                       (arg-type (get-slot name))
                       (when supplied-test-p
                         (vars supplied-test))))
                    (t
                     (do-default arg)))))

          (when rest
            (let ((rest (car rest)))
              (arglist '&rest rest)
              (vars rest)
              (ftype-args '&rest)
              (arg-type t)
              (decls `(type list ,rest))))

          (when (ll-kwds-keyp llks)
            (arglist '&key)
            (ftype-args '&key)
            (dolist (key keys)
              (if (consp key)
                  (destructuring-bind (wot
                                       &optional
                                       (def nil def-p)
                                       (supplied-test nil supplied-test-p))
                      key
                    (multiple-value-bind (key name)
                        (if (consp wot)
                            (destructuring-bind (key var) wot
                              (values key var))
                            (values (keywordicate wot) wot))
                      (multiple-value-bind (type slot-def)
                          (get-slot name)
                        (arglist `(,wot ,(if def-p def slot-def)
                                        ,@(if supplied-test-p `(,supplied-test) nil)))
                        (vars name)
                        (arg-type type key name)
                        (when supplied-test-p
                          (vars supplied-test)))))
                  (do-default key t))))

          (when (ll-kwds-allowp llks)
            (arglist '&allow-other-keys)
            (ftype-args '&allow-other-keys))

          ;; PARSE-LAMBDA-LIST doesn't distinguish between &AUX with nothing
          ;; after it, and absence of &AUX. They mean the same thing, even as
          ;; "interesting" as &AUX can be in a BOA lambda list [CLHS 3.4.6]
          (when aux
            (arglist '&aux)
            (dolist (arg aux)
              (typecase arg
                ((cons symbol cons)
                 (let ((var (first arg)))
                   (arglist arg)
                   (vars var)
                   (decls `(type ,(get-slot var) ,var))))
                (t
                 ;; (&AUX X) and (&AUX (X)) both skip the slot
                 (skipped-vars (if (consp arg) (first arg) arg))))))))

      (funcall creator defstruct (first boa)
               (arglist) (ftype-args) (decls)
               (loop for slot in (dd-slots defstruct)
                     for name = (dsd-name slot)
                     collect (cond ((find name (skipped-vars) :test #'string=)
                                    ;; CLHS 3.4.6 Boa Lambda Lists
                                    '.do-not-initialize-slot.)
                                   ((or (find (dsd-name slot) (vars) :test #'string=)
                                        (let ((type (dsd-type slot)))
                                          (if (eq t type)
                                              (dsd-default slot)
                                              `(the ,type ,(dsd-default slot))))))))))))

;;; Grovel the constructor options, and decide what constructors (if
;;; any) to create.
(defun constructor-definitions (defstruct)
  (let ((no-constructors nil)
        (boas ())
        (defaults ())
        (creator (ecase (dd-type defstruct)
                   (structure #'create-structure-constructor)
                   (vector #'create-vector-constructor)
                   (list #'create-list-constructor))))
    (dolist (constructor (dd-constructors defstruct))
      (destructuring-bind (name &optional (boa-ll nil boa-p)) constructor
        (declare (ignore boa-ll))
        (cond ((not name) (setq no-constructors t))
              (boa-p (push constructor boas))
              (t (push name defaults)))))

    (when no-constructors
      (when (or defaults boas)
        (error "(:CONSTRUCTOR NIL) combined with other :CONSTRUCTORs"))
      (return-from constructor-definitions ()))

    (unless (or defaults boas)
      (push (symbolicate "MAKE-" (dd-name defstruct)) defaults))

    (collect ((res))
      (when defaults
        (let ((cname (first defaults)))
          (setf (dd-default-constructor defstruct) cname)
          (multiple-value-bind (cons ftype)
              (create-keyword-constructor defstruct creator)
            (res `(declaim (ftype ,ftype ,@defaults)))
            (res cons))
          (dolist (other-name (rest defaults))
            (res `(setf (fdefinition ',other-name) (fdefinition ',cname))))))

      (dolist (boa boas)
        (multiple-value-bind (cons ftype)
            (create-boa-constructor defstruct boa creator)
          (res `(declaim (ftype ,ftype ,(first boa))))
          (res cons)))

      (res))))

(defun accessor-definitions (dd)
  (loop for dsd in (dd-slots dd)
        for accessor-name = (dsd-accessor-name dsd)
        for place-form = (%accessor-place-form dd dsd `(the ,(dd-name dd) instance))
        unless (accessor-inherited-data accessor-name dd)
        collect
        `(defun ,accessor-name (instance)
           ,(cond ((not (dsd-type dsd))
                   place-form)
                  ((dsd-safe-p dsd)
                   `(truly-the ,(dsd-type dsd) ,place-form))
                  (t
                   `(the ,(dsd-type dsd) ,place-form))))
        and unless (dsd-read-only dsd)
        collect
        `(defun (setf ,accessor-name) (value instance)
           (setf ,place-form (the ,(dsd-type dsd) value)))))

(defun copier-definition (dd)
  (when (dd-copier-name dd)
    `(defun ,(dd-copier-name dd) (instance)
       (copy-structure (the ,(dd-name dd) instance)))))

(defun predicate-definition (dd)
  (when (dd-predicate-name dd)
    `(defun ,(dd-predicate-name dd) (object)
       (typep object ',(dd-name dd)))))


;;;; instances with ALTERNATE-METACLASS
;;;;
;;;; The CMU CL support for structures with ALTERNATE-METACLASS was a
;;;; fairly general extension embedded in the main DEFSTRUCT code, and
;;;; the result was an fairly impressive mess as ALTERNATE-METACLASS
;;;; extension mixed with ANSI CL generality (e.g. :TYPE and :INCLUDE)
;;;; and CMU CL implementation hairiness (esp. raw slots). This SBCL
;;;; version is much less ambitious, noticing that ALTERNATE-METACLASS
;;;; is only used to implement CONDITION, STANDARD-INSTANCE, and
;;;; GENERIC-FUNCTION, and defining a simple specialized
;;;; separate-from-DEFSTRUCT macro to provide only enough
;;;; functionality to support those.
;;;;
;;;; KLUDGE: The defining macro here is so specialized that it's ugly
;;;; in its own way. It also violates once-and-only-once by knowing
;;;; much about structures and layouts that is already known by the
;;;; main DEFSTRUCT macro. Hopefully it will go away presently
;;;; (perhaps when CL:CLASS and SB-PCL:CLASS meet) as per FIXME below.
;;;; -- WHN 2001-10-28
;;;;
;;;; FIXME: There seems to be no good reason to shoehorn CONDITION,
;;;; STANDARD-INSTANCE, and GENERIC-FUNCTION into mutated structures
;;;; instead of just implementing them as primitive objects. (This
;;;; reduced-functionality macro seems pretty close to the
;;;; functionality of !DEFINE-PRIMITIVE-OBJECT..)

;;; The complete list of alternate-metaclass DEFSTRUCTs:
;;;   CONDITION SB-EVAL:INTERPRETED-FUNCTION
;;;   SB-PCL::STANDARD-INSTANCE SB-PCL::STANDARD-FUNCALLABLE-INSTANCE
;;;   SB-PCL::CTOR SB-PCL::%METHOD-FUNCTION
;;;
(defun make-dd-with-alternate-metaclass (&key (class-name (missing-arg))
                                              (superclass-name (missing-arg))
                                              (metaclass-name (missing-arg))
                                              (dd-type (missing-arg))
                                              metaclass-constructor
                                              slot-names)
  (let* ((dd (make-defstruct-description class-name))
         (conc-name (concatenate 'string (symbol-name class-name) "-"))
         (dd-slots (let ((reversed-result nil)
                         ;; The index starts at 1 for ordinary named
                         ;; slots because slot 0 is magical, used for
                         ;; the LAYOUT in CONDITIONs and
                         ;; FUNCALLABLE-INSTANCEs.  (This is the same
                         ;; in ordinary structures too: see (INCF
                         ;; DD-LENGTH) in
                         ;; PARSE-DEFSTRUCT-NAME-AND-OPTIONS).
                         (index 1))
                     (dolist (slot-name slot-names)
                       (push (make-defstruct-slot-description
                              :name slot-name
                              :index index
                              :accessor-name (symbolicate conc-name slot-name))
                             reversed-result)
                       (incf index))
                     (nreverse reversed-result))))
    ;; We do *not* fill in the COPIER-NAME and PREDICATE-NAME
    ;; because none of the magical alternate-metaclass structures
    ;; have copiers and predicates that "Just work"
    (case dd-type
      ;; We don't support inheritance of alternate metaclass stuff,
      ;; and it's not a general-purpose facility, so sanity check our
      ;; own code.
      (structure
       (aver (eq superclass-name 't)))
      (funcallable-structure
       (aver (eq superclass-name 'function)))
      (t (bug "Unknown DD-TYPE in ALTERNATE-METACLASS: ~S" dd-type)))
    (setf (dd-alternate-metaclass dd) (list superclass-name
                                            metaclass-name
                                            metaclass-constructor)
          (dd-slots dd) dd-slots
          (dd-length dd) (1+ (length slot-names))
          (dd-type dd) dd-type)
    dd))

;;; make !DEFSTRUCT-WITH-ALTERNATE-METACLASS compilable by the host
;;; lisp, installing the information we need to reason about the
;;; structures (layouts and classoids).
;;;
;;; FIXME: we should share the parsing and the DD construction between
;;; this and the cross-compiler version, but my brain was too small to
;;; get that right.  -- CSR, 2006-09-14
#+sb-xc-host
(defmacro !defstruct-with-alternate-metaclass
    (class-name &key
                (slot-names (missing-arg))
                (boa-constructor (missing-arg))
                (superclass-name (missing-arg))
                (metaclass-name (missing-arg))
                (metaclass-constructor (missing-arg))
                (dd-type (missing-arg))
                predicate
                (runtime-type-checks-p t))

  (declare (type (and list (not null)) slot-names))
  (declare (type (and symbol (not null))
                 boa-constructor
                 superclass-name
                 metaclass-name
                 metaclass-constructor))
  (declare (type symbol predicate))
  (declare (type (member structure funcallable-structure) dd-type))
  (declare (ignore boa-constructor predicate runtime-type-checks-p))

  (let* ((dd (make-dd-with-alternate-metaclass
              :class-name class-name
              :slot-names slot-names
              :superclass-name superclass-name
              :metaclass-name metaclass-name
              :metaclass-constructor metaclass-constructor
              :dd-type dd-type)))
    `(progn

      (eval-when (:compile-toplevel :load-toplevel :execute)
        (%compiler-set-up-layout ',dd ',(!inherits-for-structure dd))))))

(sb!xc:proclaim '(special *defstruct-hooks*))

(sb!xc:defmacro !defstruct-with-alternate-metaclass
    (class-name &key
                (slot-names (missing-arg))
                (boa-constructor (missing-arg))
                (superclass-name (missing-arg))
                (metaclass-name (missing-arg))
                (metaclass-constructor (missing-arg))
                (dd-type (missing-arg))
                predicate
                (runtime-type-checks-p t))

  (declare (type (and list (not null)) slot-names))
  (declare (type (and symbol (not null))
                 boa-constructor
                 superclass-name
                 metaclass-name
                 metaclass-constructor))
  (declare (type symbol predicate))
  (declare (type (member structure funcallable-structure) dd-type))

  (let* ((dd (make-dd-with-alternate-metaclass
              :class-name class-name
              :slot-names slot-names
              :superclass-name superclass-name
              :metaclass-name metaclass-name
              :metaclass-constructor metaclass-constructor
              :dd-type dd-type))
         (dd-slots (dd-slots dd))
         (dd-length (1+ (length slot-names)))
         (object-gensym (make-symbol "OBJECT"))
         (new-value-gensym (make-symbol "NEW-VALUE"))
         (delayed-layout-form `(%delayed-get-compiler-layout ,class-name)))
    (multiple-value-bind (raw-maker-form raw-reffer-operator)
        (ecase dd-type
          (structure
           (values `(%make-structure-instance-macro ,dd nil)
                   '%instance-ref))
          (funcallable-structure
           (values `(let ((,object-gensym
                           (%make-funcallable-instance ,dd-length)))
                      (setf (%funcallable-instance-layout ,object-gensym)
                            ,delayed-layout-form)
                      ,object-gensym)
                   '%funcallable-instance-info)))
      `(progn

         (eval-when (:compile-toplevel :load-toplevel :execute)
           (%compiler-set-up-layout ',dd ',(!inherits-for-structure dd)))

         ;; slot readers and writers
         (declaim (inline ,@(mapcar #'dsd-accessor-name dd-slots)))
         ,@(mapcar (lambda (dsd)
                     `(defun ,(dsd-accessor-name dsd) (,object-gensym)
                        ,@(when runtime-type-checks-p
                            `((declare (type ,class-name ,object-gensym))))
                        (,raw-reffer-operator ,object-gensym
                                              ,(dsd-index dsd))))
                   dd-slots)
         (declaim (inline ,@(mapcar (lambda (dsd)
                                      `(setf ,(dsd-accessor-name dsd)))
                                    dd-slots)))
         ,@(mapcar (lambda (dsd)
                     `(defun (setf ,(dsd-accessor-name dsd)) (,new-value-gensym
                                                              ,object-gensym)
                        ,@(when runtime-type-checks-p
                            `((declare (type ,class-name ,object-gensym))))
                        (setf (,raw-reffer-operator ,object-gensym
                                                    ,(dsd-index dsd))
                              ,new-value-gensym)))
                   dd-slots)

         ;; constructor
         (defun ,boa-constructor ,slot-names
           (let ((,object-gensym ,raw-maker-form))
             ,@(mapcar (lambda (slot-name)
                         (let ((dsd (or (find slot-name dd-slots
                                              :key #'dsd-name :test #'string=)
                                        (bug "Bogus alt-metaclass boa ctor"))))
                           `(setf (,(dsd-accessor-name dsd) ,object-gensym)
                                  ,slot-name)))
                       slot-names)
             ,object-gensym))

         ;; predicate
         ,@(when predicate
             ;; Just delegate to the compiler's type optimization
             ;; code, which knows how to generate inline type tests
             ;; for the whole CMU CL INSTANCE menagerie.
             `(defun ,predicate (,object-gensym)
                (typep ,object-gensym ',class-name)))

         ;; Usually we AVER instead of ASSERT, but one alternate-metaclass
         ;; structure definition is cross-compiled before AVER is a known macro.
         ;; It could be a def!macro perhaps, but ASSERT works just fine here
         ;; without adding to image size, since these toplevel forms
         ;; belong to code that is discarded after cold-init.
         (assert (null *defstruct-hooks*))))))

;;;; finalizing bootstrapping

;;; Set up DD and LAYOUT for STRUCTURE-OBJECT class itself.
;;;
;;; Ordinary structure classes effectively :INCLUDE STRUCTURE-OBJECT
;;; when they have no explicit :INCLUDEs, so (1) it needs to be set up
;;; before we can define ordinary structure classes, and (2) it's
;;; special enough (and simple enough) that we just build it by hand
;;; instead of trying to generalize the ordinary DEFSTRUCT code.
(defun !set-up-structure-object-class ()
  (let ((dd (make-defstruct-description 'structure-object)))
    (setf
     (dd-slots dd) nil
     (dd-length dd) 1
     (dd-type dd) 'structure)
    (%compiler-set-up-layout dd)))
#+sb-xc-host(!set-up-structure-object-class)

;;; early structure predeclarations: Set up DD and LAYOUT for ordinary
;;; (non-ALTERNATE-METACLASS) structures which are needed early.
(dolist (args
         '#.(sb-cold:read-from-file
             "src/code/early-defstruct-args.lisp-expr"))
  (let* ((dd (parse-defstruct-name-and-options-and-slot-descriptions
              (first args)
              (rest args)))
         (inherits (!inherits-for-structure dd)))
    (%compiler-defstruct dd inherits)))

(defun find-defstruct-description (name &optional (errorp t))
  (let* ((classoid (find-classoid name errorp))
         (info (and classoid
                    (layout-info (classoid-layout classoid)))))
    (cond ((defstruct-description-p info)
           info)
          (errorp
           (error "No DEFSTRUCT-DESCRIPTION for ~S." name)))))

(defun structure-instance-accessor-p (name)
  (let ((info (info :function :source-transform name)))
    (and (listp info)
         (defstruct-slot-description-p (cdr info))
         info)))

;;; These functions are required to emulate SBCL kernel functions
;;; in a vanilla ANSI Common Lisp cross-compilation host.
;;; The emulation doesn't need to be efficient, since it's needed
;;; only for object dumping.
#+sb-xc-host
(progn
  (defun xc-dumpable-structure-instance-p (x)
    (and (typep x 'cl:structure-object)
         (let ((name (type-of x)))
           ;; Don't allow totally random structures, only ones that the
           ;; cross-compiler has been advised will work.
           (and (get name :sb-xc-allow-dumping-instances)
                ;; but we must also have cross-compiled it for real.
                (sb!kernel::compiler-layout-ready-p name)
                ;; and I don't know anything about raw slots
                ;; Coincidentally, in either representation of
                ;; raw-slot-metadata, 0 represents no untagged slots.
                (zerop (layout-raw-slot-metadata
                        (info :type :compiler-layout name)))))))
  (defun %instance-layout (instance)
    (aver (or (typep instance 'structure!object)
              (xc-dumpable-structure-instance-p instance)))
    (classoid-layout (find-classoid (type-of instance))))
  (defun %instance-length (instance)
    ;; INSTANCE-LENGTH tells you how many data words the backend is able to
    ;; physically access in this structure. Since every structure occupies
    ;; an even number of words, the storage slots comprise an odd number
    ;; of words after subtracting 1 for the header.
    ;; And in fact the fasl dumper / loader do write and read potentially
    ;; one cell beyond the instance's LAYOUT-LENGTH if it was not odd.
    ;; I'm not sure whether that is a good or bad thing.
    ;; But be that as it may, in the cross-compiler you must not access
    ;; more cells than there are in the declared structure because there
    ;; is no lower level storage that you can peek at.
    ;; So INSTANCE-LENGTH is exactly the same as LAYOUT-LENGTH on the host.
    (layout-length (%instance-layout instance)))
  (defun %instance-ref (instance index)
    (let ((layout (%instance-layout instance)))
      ;; with compact headers, 0 is an ordinary slot index.
      ;; without, it's the layout.
      (if (eql index (1- sb!vm:instance-data-start))
          (error "XC Host should use %INSTANCE-LAYOUT, not %INSTANCE-REF 0")
          (let* ((dd (layout-info layout))
                 ;; If data starts at 1, then subtract 1 from index.
                 ;; otherwise use the index as-is.
                 (dsd (elt (dd-slots dd)
                           (- index sb!vm:instance-data-start)))
                 (accessor-name (dsd-accessor-name dsd)))
            ;; Why AVER these: because it is slightly abstraction-breaking
            ;; to assume that the slot-index N is the NTH item in the DSDs.
            ;; The target Lisp never assumes that.
            (aver (and (eql (dsd-index dsd) index) (eq (dsd-raw-type dsd) t)))
            (funcall accessor-name instance)))))
  ;; Setting with (FUNCALL `(SETF ,accessor) ...) is unportable because
  ;;  "The mechanism by which defstruct arranges for slot accessors to be
  ;;   usable with setf is implementation-dependent; for example, it may
  ;;   use setf functions, setf expanders, or some other
  ;;   implementation-dependent mechanism ..."
  ;; But such capability seems not to be needed.
  (defun %instance-set (instance index new-value)
    (declare (ignore instance index new-value))
    (error "Can not use %INSTANCE-SET on cross-compilation host.")))

(/show0 "code/defstruct.lisp end of file")
