;;;; 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 res))))

;;; 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))))))

;;; Get layout right away.
(sb!xc:defmacro compile-time-find-layout (name)
  (find-layout name))

;;; 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.
(def!struct (defstruct-description
	     (:conc-name dd-)
	     (:make-load-form-fun just-dump-it-normally)
	     #-sb-xc-host (:pure t)
	     (:constructor make-defstruct-description
			   (name &aux
				 (conc-name (symbolicate name "-"))
				 (copier-name (symbolicate "COPY-" name))
				 (predicate-name (symbolicate name "-P")))))
  ;; name of the structure
  (name (missing-arg) :type symbol :read-only t)
  ;; documentation on the structure
  (doc nil :type (or string null))
  ;; prefix for slot names. If NIL, none.
  (conc-name nil :type (or symbol null))
  ;; the name of the primary standard keyword constructor, or NIL if none
  (default-constructor nil :type (or symbol null))
  ;; all the explicit :CONSTRUCTOR specs, with name defaulted
  (constructors () :type list)
  ;; name of copying function
  (copier-name nil :type (or symbol null))
  ;; name of type predicate
  (predicate-name nil :type (or symbol null))
  ;; the arguments to the :INCLUDE option, or NIL if no included
  ;; structure
  (include nil :type list)
  ;; properties used to define structure-like classes with an
  ;; arbitrary superclass and that may not have STRUCTURE-CLASS as the
  ;; metaclass. Syntax is:
  ;;    (superclass-name metaclass-name metaclass-constructor)
  (alternate-metaclass nil :type list)
  ;; a list of DEFSTRUCT-SLOT-DESCRIPTION objects for all slots
  ;; (including included ones)
  (slots () :type list)
  ;; a list of (NAME . INDEX) pairs for accessors of included structures
  (inherited-accessor-alist () :type list)
  ;; number of elements we've allocated (See also RAW-LENGTH.)
  (length 0 :type index)
  ;; General kind of implementation.
  (type 'structure :type (member structure vector list
				 funcallable-structure))

  ;; The next three slots are for :TYPE'd structures (which aren't
  ;; classes, DD-CLASS-P = NIL)
  ;;
  ;; vector element type
  (element-type t)
  ;; T if :NAMED was explicitly specified, NIL otherwise
  (named nil :type boolean)
  ;; any INITIAL-OFFSET option on this direct type
  (offset nil :type (or index null))

  ;; the argument to the PRINT-FUNCTION option, or NIL if a
  ;; PRINT-FUNCTION option was given with no argument, or 0 if no
  ;; PRINT-FUNCTION option was given
  (print-function 0 :type (or cons symbol (member 0)))
  ;; the argument to the PRINT-OBJECT option, or NIL if a PRINT-OBJECT
  ;; option was given with no argument, or 0 if no PRINT-OBJECT option
  ;; was given
  (print-object 0 :type (or cons symbol (member 0)))
  ;; the index of the raw data vector and the number of words in it,
  ;; or NIL and 0 if not allocated (either because this structure
  ;; has no raw slots, or because we're still parsing it and haven't
  ;; run across any raw slots yet)
  (raw-index nil :type (or index null))
  (raw-length 0 :type index)
  ;; the value of the :PURE option, or :UNSPECIFIED. This is only
  ;; meaningful if DD-CLASS-P = T.
  (pure :unspecified :type (member t nil :substructure :unspecified)))
(def!method print-object ((x defstruct-description) stream)
  (print-unreadable-object (x stream :type t)
    (prin1 (dd-name x) stream)))

;;; Does DD describe a structure with a class?
(defun dd-class-p (dd)
  (member (dd-type dd)
	  '(structure funcallable-structure)))

;;; a type name which can be used when declaring things which operate
;;; on structure instances
(defun dd-declarable-type (dd)
  (if (dd-class-p dd)
      ;; Native classes are known to the type system, and we can
      ;; declare them as types.
      (dd-name dd)
      ;; Structures layered on :TYPE LIST or :TYPE VECTOR aren't part
      ;; of the type system, so all we can declare is the underlying
      ;; LIST or VECTOR type.
      (dd-type dd)))

(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)
  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. Mostly. (KLUDGE: If the raw slot has
  ;; type (UNSIGNED-BYTE 32), the value here is UNSIGNED-BYTE, not
  ;; (UNSIGNED-BYTE 32).)
  (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
			    unsigned-byte))
  (read-only nil :type (member t nil)))
(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

(eval-when (#-sb-xc :compile-toplevel :load-toplevel :execute)

  ;; information about how a slot of a given DSD-RAW-TYPE is to be accessed
  (defstruct raw-slot-data
    ;; the raw slot type, or T for a non-raw slot
    ;;
    ;; (Raw slots are allocated in the raw slots array in a vector which
    ;; the GC doesn't need to scavenge. Non-raw slots are in the
    ;; ordinary place you'd expect, directly indexed off the instance
    ;; pointer.)
    (raw-type (missing-arg) :type (or symbol cons) :read-only t)
    ;; What operator is used (on the raw data vector) to access a slot
    ;; of this type?
    (accessor-name (missing-arg) :type symbol :read-only t)
    ;; How many words are each value of this type? (This is used to
    ;; rescale the offset into the raw data vector.)
    (n-words (missing-arg) :type (and index (integer 1)) :read-only t))

  (defvar *raw-slot-data-list*
    (list
     ;; The compiler thinks that the raw data vector is a vector of
     ;; word-sized unsigned bytes, so if the slot we want to access
     ;; actually *is* an unsigned byte, it'll access the slot for us
     ;; even if we don't lie to it at all, just let it use normal AREF.
     (make-raw-slot-data :raw-type 'unsigned-byte
			 :accessor-name 'aref
			 :n-words 1)
     ;; In the other cases, we lie to the compiler, making it use
     ;; some low-level AREFish access in order to pun the hapless
     ;; bits into some other-than-unsigned-byte meaning.
     ;;
     ;; "A lie can travel halfway round the world while the truth is
     ;; putting on its shoes." -- Mark Twain
     (make-raw-slot-data :raw-type 'single-float
			 :accessor-name '%raw-ref-single
			 :n-words 1)
     (make-raw-slot-data :raw-type 'double-float
			 :accessor-name '%raw-ref-double
			 :n-words 2)
     (make-raw-slot-data :raw-type 'complex-single-float
			 :accessor-name '%raw-ref-complex-single
			 :n-words 2)
     (make-raw-slot-data :raw-type 'complex-double-float
			 :accessor-name '%raw-ref-complex-double
			 :n-words 4)
     #!+long-float
     (make-raw-slot-data :raw-type long-float
			 :accessor-name '%raw-ref-long
			 :n-words #!+x86 3 #!+sparc 4)
     #!+long-float
     (make-raw-slot-data :raw-type complex-long-float
			 :accessor-name '%raw-ref-complex-long
			 :n-words #!+x86 6 #!+sparc 8))))

;;;; the legendary DEFSTRUCT macro itself (both CL:DEFSTRUCT and its
;;;; close personal friend SB!XC:DEFSTRUCT)

;;; Return a list of forms to install PRINT and MAKE-LOAD-FORM funs,
;;; mentioning them in the expansion so that they can be compiled.
(defun class-method-definitions (defstruct)
  (let ((name (dd-name defstruct)))
    `((locally
	;; KLUDGE: There's a FIND-CLASS DEFTRANSFORM for constant
	;; class names which creates fast but non-cold-loadable,
	;; non-compact code. In this context, we'd rather have
	;; compact, cold-loadable code. -- WHN 19990928
	(declare (notinline find-classoid))
	,@(let ((pf (dd-print-function defstruct))
		(po (dd-print-object defstruct))
		(x (gensym))
		(s (gensym)))
	    ;; Giving empty :PRINT-OBJECT or :PRINT-FUNCTION options
	    ;; leaves PO or PF equal to NIL. The user-level effect is
	    ;; to generate a PRINT-OBJECT method specialized for the type,
	    ;; implementing the default #S structure-printing behavior.
	    (when (or (eq pf nil) (eq po nil))
	      (setf pf '(default-structure-print)
		    po 0))
	    (flet (;; Given an arg from a :PRINT-OBJECT or :PRINT-FUNCTION
		   ;; option, return the value to pass as an arg to FUNCTION.
		   (farg (oarg)
		     (destructuring-bind (fun-name) oarg
		       fun-name)))
	      (cond ((not (eql pf 0))
		     `((def!method print-object ((,x ,name) ,s)
			 (funcall #',(farg pf)
				  ,x
				  ,s
				  *current-level-in-print*))))
		    ((not (eql po 0))
		     `((def!method print-object ((,x ,name) ,s)
			 (funcall #',(farg po) ,x ,s))))
		    (t nil))))
	,@(let ((pure (dd-pure defstruct)))
	    (cond ((eq pure t)
		   `((setf (layout-pure (classoid-layout
					 (find-classoid ',name)))
			   t)))
		  ((eq pure :substructure)
		   `((setf (layout-pure (classoid-layout
					 (find-classoid ',name)))
			   0)))))
	,@(let ((def-con (dd-default-constructor defstruct)))
	    (when (and def-con (not (dd-alternate-metaclass defstruct)))
	      `((setf (structure-classoid-constructor (find-classoid ',name))
		      #',def-con))))))))

;;; shared logic for CL:DEFSTRUCT and SB!XC:DEFSTRUCT
(defmacro !expander-for-defstruct (name-and-options
				   slot-descriptions
				   expanding-into-code-for-xc-host-p)
  `(let ((name-and-options ,name-and-options)
	 (slot-descriptions ,slot-descriptions)
	 (expanding-into-code-for-xc-host-p
	  ,expanding-into-code-for-xc-host-p))
     (let* ((dd (parse-defstruct-name-and-options-and-slot-descriptions
		 name-and-options
		 slot-descriptions))
	    (name (dd-name dd)))
       (if (dd-class-p dd)
	   (let ((inherits (inherits-for-structure dd)))
	     `(progn
		;; 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.
	        (with-single-package-locked-error
		    (:symbol ',name "defining ~A as a structure"))
		(%defstruct ',dd ',inherits)
		(eval-when (:compile-toplevel :load-toplevel :execute)
		  (%compiler-defstruct ',dd ',inherits))
		,@(unless expanding-into-code-for-xc-host-p
		    (append ;; FIXME: We've inherited from CMU CL nonparallel
			    ;; code for creating copiers for typed and untyped
			    ;; structures. This should be fixed.
			    ;(copier-definition dd)
			    (constructor-definitions dd)
			    (class-method-definitions dd)))
		',name))
	   `(progn
	      (with-single-package-locked-error
		  (:symbol ',name "defining ~A as a structure"))
	      (eval-when (:compile-toplevel :load-toplevel :execute)
		(setf (info :typed-structure :info ',name) ',dd))
	      ,@(unless expanding-into-code-for-xc-host-p
		  (append (typed-accessor-definitions dd)
			  (typed-predicate-definitions dd)
			  (typed-copier-definitions dd)
			  (constructor-definitions dd)))
	      ',name)))))

(sb!xc:defmacro defstruct (name-and-options &rest slot-descriptions)
  #!+sb-doc
  "DEFSTRUCT {Name | (Name Option*)} {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 nil))
#+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 t))

;;;; 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 (gensym)))
    (when (and predicate-name (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))
	      (slot-type `(and ,(dsd-type slot)
			       ,(dd-element-type defstruct))))
	  (let ((inherited (accessor-inherited-data name defstruct)))
	    (cond
	      ((not inherited)
	       (stuff `(declaim (inline ,name (setf ,name))))
	       ;; FIXME: The arguments in the next two DEFUNs should
	       ;; be gensyms. (Otherwise e.g. if NEW-VALUE happened to
	       ;; be the name of a special variable, things could get
	       ;; weird.)
	       (stuff `(defun ,name (structure)
			(declare (type ,ltype structure))
			(the ,slot-type (elt structure ,index))))
	       (unless (dsd-read-only slot)
		 (stuff
		  `(defun (setf ,name) (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

(defun require-no-print-options-so-far (defstruct)
  (unless (and (eql (dd-print-function defstruct) 0)
	       (eql (dd-print-object defstruct) 0))
    (error "No more than one of the following options may be specified:
  :PRINT-FUNCTION, :PRINT-OBJECT, :TYPE")))

;;; Parse a single DEFSTRUCT option and store the results in DD.
(defun parse-1-dd-option (option dd)
  (let ((args (rest option))
	(name (dd-name dd)))
    (case (first option)
      (:conc-name
       (destructuring-bind (&optional conc-name) args
	 (setf (dd-conc-name dd)
	       (if (symbolp conc-name)
		   conc-name
		   (make-symbol (string conc-name))))))
      (:constructor
       (destructuring-bind (&optional (cname (symbolicate "MAKE-" name))
				      &rest stuff)
	   args
	 (push (cons cname stuff) (dd-constructors dd))))
      (:copier
       (destructuring-bind (&optional (copier (symbolicate "COPY-" name)))
	   args
	 (setf (dd-copier-name dd) copier)))
      (:predicate
       (destructuring-bind (&optional (predicate-name (symbolicate name "-P")))
	   args
	 (setf (dd-predicate-name dd) predicate-name)))
      (:include
       (when (dd-include dd)
	 (error "more than one :INCLUDE option"))
       (setf (dd-include dd) args))
      (:print-function
       (require-no-print-options-so-far dd)
       (setf (dd-print-function dd)
	     (the (or symbol cons) args)))
      (:print-object
       (require-no-print-options-so-far dd)
       (setf (dd-print-object dd)
	     (the (or symbol cons) args)))
      (:type
       (destructuring-bind (type) args
	 (cond ((member type '(list vector))
		(setf (dd-element-type dd) t)
		(setf (dd-type dd) type))
	       ((and (consp type) (eq (first type) 'vector))
		(destructuring-bind (vector vtype) type
		  (declare (ignore vector))
		  (setf (dd-element-type dd) vtype)
		  (setf (dd-type dd) 'vector)))
	       (t
		(error "~S is a bad :TYPE for DEFSTRUCT." type)))))
      (:named
       (error "The DEFSTRUCT option :NAMED takes no arguments."))
      (:initial-offset
       (destructuring-bind (offset) args
	 (setf (dd-offset dd) offset)))
      (:pure
       (destructuring-bind (fun) args
	 (setf (dd-pure dd) fun)))
      (t (error "unknown DEFSTRUCT option:~%  ~S" option)))))

;;; 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
    (aver name) ; A null name doesn't seem to make sense here.
    (let ((dd (make-defstruct-description name)))
      (dolist (option options)
	(cond ((eq option :named)
	       (setf (dd-named dd) t))
	      ((consp option)
	       (parse-1-dd-option option dd))
	      ((member option '(:conc-name :constructor :copier :predicate))
	       (parse-1-dd-option (list option) dd))
	      (t
	       (error "unrecognized DEFSTRUCT option: ~S" option))))

      (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
	 (require-no-print-options-so-far dd)
	 (when (dd-named dd)
	   (incf (dd-length dd)))
	 (let ((offset (dd-offset dd)))
	   (when offset (incf (dd-length dd) offset)))))

      (when (dd-include dd)
	(frob-dd-inclusion-stuff dd))

      dd)))

;;; 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)))
    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
	 (when (keywordp spec)
	   (style-warn "Keyword slot name indicates probable syntax ~
                        error in DEFSTRUCT: ~S."
		       spec))
	 spec)
	(cons
	 (destructuring-bind
	       (name
		&optional (default nil default-p)
		&key (type nil type-p) (read-only nil ro-p))
	     spec
	   (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
	     :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 ~S 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 (VALUES RAW? RAW-TYPE WORDS), where
;;;   RAW? is true if TYPE should be stored in a raw slot.
;;;   RAW-TYPE is the raw slot type, or NIL if no raw slot.
;;;   WORDS is the number of words in the raw slot, or NIL if no raw slot.
;;;
;;; FIXME: This should use the data in *RAW-SLOT-DATA-LIST*.
(defun structure-raw-slot-type-and-size (type)
  (cond ((and (sb!xc:subtypep type 'sb!vm:word)
	      (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?.)
		(and (not fixnum?) fixnum-certain?)))
	 (values t 'unsigned-byte 1))
	((sb!xc:subtypep type 'single-float)
	 (values t 'single-float 1))
	((sb!xc:subtypep type 'double-float)
	 (values t 'double-float 2))
	#!+long-float
	((sb!xc:subtypep type 'long-float)
	 (values t 'long-float #!+x86 3 #!+sparc 4))
	((sb!xc:subtypep type '(complex single-float))
	 (values t 'complex-single-float 2))
	((sb!xc:subtypep type '(complex double-float))
	 (values t 'complex-double-float 4))
	#!+long-float
	((sb!xc:subtypep type '(complex long-float))
	 (values t 'complex-long-float #!+x86 6 #!+sparc 8))
	(t
	 (values nil nil nil))))

;;; Allocate storage for a DSD in DD. This is where we decide whether
;;; a slot is raw or not. If raw, and we haven't allocated a raw-index
;;; yet for the raw data vector, then do it. Raw objects are aligned
;;; on the unit of their size.
(defun allocate-1-slot (dd dsd)
  (multiple-value-bind (raw? raw-type words)
      (if (eq (dd-type dd) 'structure)
	  (structure-raw-slot-type-and-size (dsd-type dsd))
	  (values nil nil nil))
    (cond ((not raw?)
	   (setf (dsd-index dsd) (dd-length dd))
	   (incf (dd-length dd)))
	  (t
	   (unless (dd-raw-index dd)
	     (setf (dd-raw-index dd) (dd-length dd))
	     (incf (dd-length dd)))
	   (let ((off (rem (dd-raw-length dd) words)))
	     (unless (zerop off)
	       (incf (dd-raw-length dd) (- words off))))
	   (setf (dsd-raw-type dsd) raw-type)
	   (setf (dsd-index dsd) (dd-raw-length dd))
	   (incf (dd-raw-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 (and (dd-alternate-metaclass included-dd)
		       ;; As of sbcl-0.pre7.73, anyway, STRUCTURE-OBJECT
		       ;; is represented with an ALTERNATE-METACLASS. But
		       ;; it's specifically OK to :INCLUDE (and PCL does)
		       ;; so in this one case, it's OK to include
		       ;; something with :ALTERNATE-METACLASS after all.
		       (not (eql included-name 'structure-object)))
	      (error "can't :INCLUDE class ~S (has alternate metaclass)"
		     included-name)))))

      (incf (dd-length dd) (dd-length included-structure))
      (when (dd-class-p dd)
	(let ((mc (rest (dd-alternate-metaclass included-structure))))
	  (when (and mc (not (dd-alternate-metaclass dd)))
	    (setf (dd-alternate-metaclass dd)
		  (cons included-name mc))))
	(when (eq (dd-pure dd) :unspecified)
	  (setf (dd-pure dd) (dd-pure included-structure)))
	(setf (dd-raw-index dd) (dd-raw-index included-structure))
	(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.
(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)
       (concatenate 'simple-vector
		    (layout-inherits super)
		    (vector super (classoid-layout (find-classoid 'stream)))))
      ((fd-stream)
       (concatenate 'simple-vector
		    (layout-inherits super)
		    (vector super 
			    (classoid-layout (find-classoid 'file-stream)))))
      ((sb!impl::string-input-stream 
	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. Define those functions which are
;;; sufficiently stereotyped that we can implement them as standard
;;; closures.
(defun %defstruct (dd inherits)
  (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
	   (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)))))))
	   (%redefine-defstruct classoid old-layout layout)
	   (setq layout (classoid-layout classoid))))
    (setf (find-classoid (dd-name dd)) classoid)

    ;; Various other operations only make sense on the target SBCL.
    #-sb-xc-host
    (%target-defstruct dd layout))

  (values))

;;; 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 or, in
	;; the case of a raw slot, to read the vector of raw slots
	(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))
	(let* ((raw-slot-data (find raw-type *raw-slot-data-list*
				    :key #'raw-slot-data-raw-type
				    :test #'equal))
	       (raw-slot-accessor (raw-slot-data-accessor-name raw-slot-data))
	       (raw-n-words (raw-slot-data-n-words raw-slot-data)))
	  (multiple-value-bind (scaled-dsd-index misalignment)
	      (floor (dsd-index dsd) raw-n-words)
	    (aver (zerop misalignment))
	    (let* ((raw-vector-bare-form
		    `(,ref ,instance-name ,(dd-raw-index dd)))
		   (raw-vector-form
		    (if (eq raw-type 'unsigned-byte)
			(progn
			  (aver (= raw-n-words 1))
			  (aver (eq raw-slot-accessor 'aref))
			  ;; FIXME: when the 64-bit world rolls
			  ;; around, this will need to be reviewed,
			  ;; along with the whole RAW-SLOT thing.
			  `(truly-the
			    (simple-array sb!vm:word (*))
			    ,raw-vector-bare-form))
			raw-vector-bare-form)))
	      `(,raw-slot-accessor ,raw-vector-form ,scaled-dsd-index)))))))

;;; Return source transforms for the reader and writer functions of
;;; the slot described by DSD. They should be inline expanded, but
;;; source transforms work faster.
(defun slot-accessor-transforms (dd dsd)
  (let ((accessor-place-form (%accessor-place-form dd dsd
                                                   `(the ,(dd-name dd) instance)))
        (dsd-type (dsd-type dsd))
        (value-the (if (dsd-safe-p dsd) 'truly-the 'the)))
    (values (sb!c:source-transform-lambda (instance)
              `(,value-the ,dsd-type ,(subst instance 'instance
                                             accessor-place-form)))
            (sb!c:source-transform-lambda (new-value instance)
              (destructuring-bind (accessor-name &rest accessor-args)
                  accessor-place-form
                (once-only ((new-value new-value)
                            (instance instance))
                  `(,(info :setf :inverse accessor-name)
                     ,@(subst instance 'instance accessor-args)
                     (the ,dsd-type ,new-value))))))))

;;; Return a LAMBDA form which can be used to set a slot.
(defun slot-setter-lambda-form (dd dsd)
  `(lambda (new-value instance)
     ,(funcall (nth-value 1 (slot-accessor-transforms dd dsd))
               '(dummy new-value instance))))

;;; 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.
				(inherits (vector (find-layout t)
						  (find-layout 'instance))))

  (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 "previously compiled" "current")
				"compiled"
				:compiler-layout clayout))
    (cond (old-layout
	   (undefine-structure (layout-classoid old-layout))
	   (when (and (classoid-subclasses classoid)
		      (not (eq layout old-layout)))
	     (collect ((subs))
		      (dohash (classoid layout (classoid-subclasses classoid))
			(declare (ignore layout))
			(undefine-structure classoid)
			(subs (classoid-proper-name classoid)))
		      (when (subs)
			(warn "removing old subclasses of ~S:~%  ~S"
			      (classoid-name classoid)
			      (subs))))))
	  (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.
(defun %compiler-defstruct (dd inherits)
  (declare (type defstruct-description dd))

  (%compiler-set-up-layout dd inherits)

  (let* ((dtype (dd-declarable-type dd)))

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

    (let ((predicate-name (dd-predicate-name dd)))
      (when predicate-name
	(sb!xc:proclaim `(ftype (sfunction (t) boolean) ,predicate-name))
	;; Provide inline expansion (or not).
	(ecase (dd-type dd)
	  ((structure funcallable-structure)
	   ;; Let the predicate be inlined.
	   (setf (info :function :inline-expansion-designator predicate-name)
		 (lambda ()
		   `(lambda (x)
		      ;; This dead simple definition works because the
		      ;; type system knows how to generate inline type
		      ;; tests for instances.
		      (typep x ',(dd-name dd))))
		 (info :function :inlinep predicate-name)
		 :inline))
	  ((list vector)
	   ;; Just punt. We could provide inline expansions for :TYPE
	   ;; LIST and :TYPE VECTOR predicates too, but it'd be a
	   ;; little messier and we don't bother. (Does anyway use
	   ;; typed DEFSTRUCTs at all, let alone for high
	   ;; performance?)
	   ))))

    (dolist (dsd (dd-slots dd))
      (let* ((accessor-name (dsd-accessor-name dsd))
	     (dsd-type (dsd-type dsd)))
	(when accessor-name
	  (let ((inherited (accessor-inherited-data accessor-name dd)))
	    (cond
	      ((not inherited)
	       (multiple-value-bind (reader-designator writer-designator)
		   (slot-accessor-transforms dd dsd)
		 (sb!xc:proclaim `(ftype (sfunction (,dtype) ,dsd-type)
				   ,accessor-name))
		 (setf (info :function :source-transform accessor-name)
		       reader-designator)
		 (unless (dsd-read-only dsd)
		   (let ((setf-accessor-name `(setf ,accessor-name)))
		     (sb!xc:proclaim
		      `(ftype (sfunction (,dsd-type ,dtype) ,dsd-type)
			,setf-accessor-name))
		     (setf (info :function :source-transform setf-accessor-name)
			   writer-designator)))))
	      ((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)))))))))
  (values))

;;;; 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))

;;; 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)
  (multiple-value-bind (class old-layout)
      (destructuring-bind
	  (&optional
	   name
	   (class 'structure-classoid)
	   (constructor 'make-structure-classoid))
	  (dd-alternate-metaclass info)
	(declare (ignore name))
	(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 (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 ((new-layout (make-layout :classoid class
				   :inherits inherits
				   :depthoid (length inherits)
				   :length (dd-length info)
				   :info info))
	  (old-layout (or compiler-layout old-layout)))
      (cond
       ((not old-layout)
	(values class new-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?"))
       ((not *type-system-initialized*)
	(setf (layout-info old-layout) info)
	(values class old-layout nil))
       ((redefine-layout-warning old-context
				 old-layout
				 new-context
				 (layout-length new-layout)
				 (layout-inherits new-layout)
				 (layout-depthoid new-layout))
	(values class new-layout old-layout))
       (t
	(let ((old-info (layout-info old-layout)))
	  (typecase old-info
	    ((or defstruct-description)
	     (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))))
	    (null
	     (setf (layout-info old-layout) info)
	     (values class old-layout nil))
	    (t
	     (error "shouldn't happen! strange thing in LAYOUT-INFO:~%  ~S"
		    old-layout)
	     (values class new-layout old-layout)))))))))

;;; 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.
(defun undefine-structure (class)
  (let ((info (layout-info (classoid-layout class))))
    (when (defstruct-description-p info)
      (let ((type (dd-name info)))
	(remhash type *typecheckfuns*)
	(setf (info :type :compiler-layout type) nil)
	(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)))
  (values))

;;; 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 vars types values)
  (let ((temp (gensym))
	(etype (dd-element-type dd)))
    `(defun ,cons-name ,arglist
       (declare ,@(mapcar (lambda (var type) `(type (and ,type ,etype) ,var))
			  vars types))
       (let ((,temp (make-array ,(dd-length dd)
				:element-type ',(dd-element-type dd))))
	 ,@(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))))
(defun create-list-constructor (dd cons-name arglist vars types 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)))

    `(defun ,cons-name ,arglist
       (declare ,@(mapcar (lambda (var type) `(type ,type ,var)) vars types))
       (list ,@vals))))
(defun create-structure-constructor (dd cons-name arglist vars types values)
  (let* ((instance (gensym "INSTANCE"))
	 (raw-index (dd-raw-index dd)))
    `(defun ,cons-name ,arglist
       (declare ,@(mapcar (lambda (var type) `(type ,type ,var))
			  vars types))
       (let ((,instance (truly-the ,(dd-name dd)
			  (%make-instance-with-layout
			   (%delayed-get-compiler-layout ,(dd-name dd))))))
	 ,@(when raw-index
	     `((setf (%instance-ref ,instance ,raw-index)
		     (make-array ,(dd-raw-length dd)
				 :element-type 'sb!vm:word))))
	 ,@(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.)
                     (unless (eq value '.do-not-initialize-slot.)
                       `(,(slot-setter-lambda-form dd dsd) ,value ,instance)))
		   (dd-slots dd)
		   values)
	 ,instance))))

;;; Create a default (non-BOA) keyword constructor.
(defun create-keyword-constructor (defstruct creator)
  (declare (type function creator))
  (collect ((arglist (list '&key))
	    (types)
	    (vals))
    (dolist (slot (dd-slots defstruct))
      (let ((dum (gensym))
	    (name (dsd-name slot)))
	(arglist `((,(keywordicate name) ,dum) ,(dsd-default slot)))
	(types (dsd-type slot))
	(vals dum)))
    (funcall creator
	     defstruct (dd-default-constructor defstruct)
	     (arglist) (vals) (types) (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 (req opt restp rest keyp keys allowp auxp aux)
      (parse-lambda-list (second boa))
    (collect ((arglist)
	      (vars)
	      (types)
              (skipped-vars))
      (labels ((get-slot (name)
		 (let ((res (find name (dd-slots defstruct)
				  :test #'string=
				  :key #'dsd-name)))
		   (if res
		       (values (dsd-type res) (dsd-default res))
		       (values t nil))))
	       (do-default (arg)
		 (multiple-value-bind (type default) (get-slot arg)
		   (arglist `(,arg ,default))
		   (vars arg)
		   (types type))))
	(dolist (arg req)
	  (arglist arg)
	  (vars arg)
	  (types (get-slot arg)))

	(when opt
	  (arglist '&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)
		     (types (get-slot name))))
		  (t
		   (do-default arg)))))

	(when restp
	  (arglist '&rest rest)
	  (vars rest)
	  (types 'list))

	(when keyp
	  (arglist '&key)
	  (dolist (key keys)
	    (if (consp key)
		(destructuring-bind (wot
                                     &optional
                                     (def nil def-p)
                                     (supplied-test nil supplied-test-p))
                    key
		  (let ((name (if (consp wot)
				  (destructuring-bind (key var) wot
				    (declare (ignore key))
				    var)
				  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)
		      (types type))))
		(do-default key))))

	(when allowp (arglist '&allow-other-keys))

	(when auxp
	  (arglist '&aux)
	  (dolist (arg aux)
            (arglist arg)
            (if (proper-list-of-length-p arg 2)
              (let ((var (first arg)))
                (vars var)
                (types (get-slot var)))
              (skipped-vars (if (consp arg) (first arg) arg))))))

      (funcall creator defstruct (first boa)
	       (arglist) (vars) (types)
               (loop for slot in (dd-slots defstruct)
                     for name = (dsd-name slot)
                     collect (cond ((find name (skipped-vars) :test #'string=)
                                    (setf (dsd-safe-p slot) nil)
                                    '.do-not-initialize-slot.)
                                   ((or (find (dsd-name slot) (vars) :test #'string=)
                                        (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) (names))
      (when defaults
        (let ((cname (first defaults)))
          (setf (dd-default-constructor defstruct) cname)
          (res (create-keyword-constructor defstruct creator))
          (names cname)
          (dolist (other-name (rest defaults))
            (res `(setf (fdefinition ',other-name) (fdefinition ',cname)))
            (names other-name))))

      (dolist (boa boas)
        (res (create-boa-constructor defstruct boa creator))
        (names (first boa)))

      (res `(declaim (ftype
                      (sfunction *
                                 ,(if (eq (dd-type defstruct) 'structure)
                                      (dd-name defstruct)
                                      '*))
                      ,@(names))))

      (res))))

;;;; 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..)

(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 LAYOUT in
			 ;; CONDITIONs or for something (?) in
			 ;; funcallable instances.
			 (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))))
    (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))

(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 (gensym "OBJECT"))
	 (new-value-gensym (gensym "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 `(let ((,object-gensym (%make-instance ,dd-length)))
		      (setf (%instance-layout ,object-gensym)
			    ,delayed-layout-form)
		      ,object-gensym)
		   '%instance-ref))
	  (funcallable-structure
	   (values `(%make-funcallable-instance ,dd-length
						,delayed-layout-form)
		   '%funcallable-instance-info)))
      `(progn

	 (eval-when (:compile-toplevel :load-toplevel :execute)
	   (%compiler-set-up-layout ',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 (find (symbol-name slot-name) dd-slots
					  :key (lambda (x)
						 (symbol-name (dsd-name x)))
					  :test #'string=)))
			   ;; KLUDGE: bug 117 bogowarning.  Neither
			   ;; DECLAREing the type nor TRULY-THE cut
			   ;; the mustard -- it still gives warnings.
			   (enforce-type dsd defstruct-slot-description)
			   `(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)))))))

;;;; 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
     ;; Note: This has an ALTERNATE-METACLASS only because of blind
     ;; clueless imitation of the CMU CL code -- dunno if or why it's
     ;; needed. -- WHN 
     (dd-alternate-metaclass dd) '(instance)
     (dd-slots dd) nil
     (dd-length dd) 1
     (dd-type dd) 'structure)
    (%compiler-set-up-layout dd)))
(!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)))

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