;;;; type-related stuff which exists only in the target SBCL runtime

;;;; 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")

(!begin-collecting-cold-init-forms)

;;; If TYPE is a type that we can do a compile-time test on, then
;;; return whether the object is of that type as the first value and
;;; second value true. Otherwise return NIL, NIL.
;;;
;;; We give up on unknown types and pick off FUNCTION- and COMPOUND-
;;; types. For STRUCTURE- types, we require that the type be defined
;;; in both the current and compiler environments, and that the
;;; INCLUDES be the same.
;;;
;;; KLUDGE: This should probably be a type method instead of a big
;;; ETYPECASE. But then the type method system should probably be CLOS
;;; too, and until that happens wedging more stuff into it might be
;;; messy. So I've left it a big ETYPECASE. -- 2001-03-16
(defun ctypep (obj type)
  (declare (type ctype type))
  (etypecase type
    ((or numeric-type
	 named-type
	 member-type
	 array-type
	 sb!xc:built-in-class
	 cons-type)
     (values (%typep obj type) t))
    (sb!xc:class
     (if (if (csubtypep type (specifier-type 'funcallable-instance))
	     (funcallable-instance-p obj)
	     (typep obj 'instance))
	 (if (eq (class-layout type)
		 (info :type :compiler-layout (sb!xc:class-name type)))
	     (values (sb!xc:typep obj type) t)
	     (values nil nil))
	 (values nil t)))
    (compound-type
     (funcall (etypecase type
		(intersection-type #'every/type)
		(union-type #'any/type))
	      #'ctypep
	      obj
	      (compound-type-types type)))
    (fun-type
     (values (functionp obj) t))
    (unknown-type
     (values nil nil))
    (alien-type-type
     (values (alien-typep obj (alien-type-type-alien-type type)) t))
    (hairy-type
     ;; Now the tricky stuff.
     (let* ((hairy-spec (hairy-type-specifier type))
	    (symbol (if (consp hairy-spec) (car hairy-spec) hairy-spec)))
       (ecase symbol
	 (and
	  (if (atom hairy-spec)
	      (values t t)
	      (dolist (spec (cdr hairy-spec) (values t t))
		(multiple-value-bind (res win)
		    (ctypep obj (specifier-type spec))
		  (unless win (return (values nil nil)))
		  (unless res (return (values nil t)))))))
	 (not
	  (multiple-value-bind (res win)
	      (ctypep obj (specifier-type (cadr hairy-spec)))
	    (if win
		(values (not res) t)
		(values nil nil))))
	 (satisfies
	  (let ((predicate-name (second hairy-spec)))
	    (declare (type symbol predicate-name)) ; by ANSI spec of SATISFIES
	    (if (fboundp predicate-name)
		(values (not (null (funcall predicate-name obj))) t)
		(values nil nil)))))))))

;;; Return the layout for an object. This is the basic operation for
;;; finding out the "type" of an object, and is used for generic
;;; function dispatch. The standard doesn't seem to say as much as it
;;; should about what this returns for built-in objects. For example,
;;; it seems that we must return NULL rather than LIST when X is NIL
;;; so that GF's can specialize on NULL.
#!-sb-fluid (declaim (inline layout-of))
(defun layout-of (x)
  (declare (optimize (speed 3) (safety 0)))
  (cond ((typep x 'instance) (%instance-layout x))
	((funcallable-instance-p x) (%funcallable-instance-layout x))
	((null x)
	 ;; Note: was #.((CLASS-LAYOUT (SB!XC:FIND-CLASS 'NULL))).
	 ;; I (WHN 19990209) replaced this with an expression evaluated at
	 ;; run time in order to make it easier to build the cross-compiler.
	 ;; If it doesn't work, something else will be needed..
	 (locally
	   ;; KLUDGE: In order to really make this run at run time
	   ;; (instead of doing some weird broken thing at cold load
	   ;; time), we need to suppress a DEFTRANSFORM.. -- WHN 19991004
	   (declare (notinline sb!xc:find-class))
	   (class-layout (sb!xc:find-class 'null))))
	(t (svref *built-in-class-codes* (widetag-of x)))))

#!-sb-fluid (declaim (inline sb!xc:class-of))
(defun sb!xc:class-of (object)
  #!+sb-doc
  "Return the class of the supplied object, which may be any Lisp object, not
   just a CLOS STANDARD-OBJECT."
  (layout-class (layout-of object)))

;;; Pull the type specifier out of a function object.
(defun extract-fun-type (fun)
  (specifier-type (%simple-fun-type (%closure-fun fun))))

;;;; miscellaneous interfaces

;;; Clear memoization of all type system operations that can be
;;; altered by type definition/redefinition.
(defun clear-type-caches ()
  (when *type-system-initialized*
    (dolist (sym '(values-specifier-type-cache-clear
		   values-type-union-cache-clear
		   type-union2-cache-clear
		   values-subtypep-cache-clear
		   csubtypep-cache-clear
		   type-intersection2-cache-clear
		   values-type-intersection-cache-clear))
      (funcall (symbol-function sym))))
  (values))

;;; This is like TYPE-OF, only we return a CTYPE structure instead of
;;; a type specifier, and we try to return the type most useful for
;;; type checking, rather than trying to come up with the one that the
;;; user might find most informative.
(declaim (ftype (function (t) ctype) ctype-of))
(defun-cached (ctype-of
	       :hash-function (lambda (x) (logand (sxhash x) #x1FF))
	       :hash-bits 9
	       :init-wrapper !cold-init-forms)
	      ((x eq))
  (typecase x
    (function
     (if (funcallable-instance-p x)
	 (sb!xc:class-of x)
	 (extract-fun-type x)))
    (symbol
     (make-member-type :members (list x)))
    (number
     (ctype-of-number x))
    (array
     (let ((etype (specifier-type (array-element-type x))))
       (make-array-type :dimensions (array-dimensions x)
			:complexp (not (typep x 'simple-array))
			:element-type etype
			:specialized-element-type etype)))
    (cons
     (make-cons-type *universal-type* *universal-type*))
    (t
     (sb!xc:class-of x))))

;;; Clear this cache on GC so that we don't hold onto too much garbage.
(pushnew 'ctype-of-cache-clear *before-gc-hooks*)

(!defun-from-collected-cold-init-forms !target-type-cold-init)