src/code/coerce.lisp

   1 ;;;; COERCE and related code
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!IMPL")
  13
  14 (macrolet ((def (name constructor access src-type &optional explicit-check)
  15              `(defun ,name (object type)
  16                 (declare (type ,src-type object))
  17                 ,@(when explicit-check `((declare (explicit-check))))
  18                 (do* ((index 0 (1+ index))
  19                       (length (length object))
  20                       (result ,constructor)
  21                       (in-object object))
  22                      ((>= index length) result)
  23                   (declare (fixnum length index))
  24                   (declare (type vector result))
  25                   (setf (,access result index)
  26                         ,(ecase src-type
  27                            (list '(pop in-object))
  28                            (vector '(aref in-object index))
  29                            (sequence '(elt in-object index))))))))
  30
  31   (def list-to-vector* (make-sequence type length) aref list t)
  32
  33   (def vector-to-vector* (make-sequence type length) aref vector t)
  34
  35   (def sequence-to-vector* (make-sequence type length) aref sequence))
  36
  37 (defun vector-to-list* (object)
  38   (declare (type vector object))
  39   (dx-let ((result (list nil)))
  40     (let ((splice result))
  41       (do-vector-data (elt object (cdr result))
  42         (let ((cell (list elt)))
  43           (setf (cdr splice) cell splice cell))))))
  44
  45 (defun sequence-to-list (sequence)
  46   (declare (type sequence sequence))
  47   (dx-let ((result (list nil)))
  48     (let ((splice result))
  49       (sb!sequence:dosequence (elt sequence (cdr result))
  50         (let ((cell (list elt)))
  51           (setf (cdr splice) cell splice cell))))))
  52
  53 ;;; These are used both by the full DEFUN function and by various
  54 ;;; optimization transforms in the constant-OUTPUT-TYPE-SPEC case.
  55 ;;;
  56 ;;; Most of them are INLINE so that they can be optimized when the
  57 ;;; argument type is known. It might be better to do this with
  58 ;;; DEFTRANSFORMs, though.
  59 (declaim (inline coerce-to-list))
  60 (declaim (inline coerce-to-vector))
  61
  62 (defun coerce-symbol-to-fun (symbol)
  63   ;; FIXME? I would think to use SYMBOL-FUNCTION here which does not strip off
  64   ;; encapsulations. But Stas wrote FDEFINITION so ...
  65   ;; [Also note, we won't encapsulate a macro or special-form, so this
  66   ;; introspective technique to decide what kind something is works either way]
  67   (let ((def (fdefinition symbol)))
  68     (declare (notinline macro/special-guard-fun-p)) ; not performance-critical
  69     (if (macro/special-guard-fun-p def)
  70         (error (ecase (car (%fun-name def))
  71                 (:macro "~S names a macro.")
  72                 (:special "~S names a special operator."))
  73                symbol)
  74         def)))
  75
  76 (defun coerce-to-fun (object)
  77   ;; (Unlike the other COERCE-TO-FOOs, this one isn't inline, because
  78   ;; it's so big and because optimizing away the outer ETYPECASE
  79   ;; doesn't seem to buy us that much anyway.)
  80   (etypecase object
  81     (function object)
  82     (symbol
  83      (coerce-symbol-to-fun object))
  84     (list
  85      (case (first object)
  86        (setf
  87         (fdefinition object))
  88        (lambda
  89         (eval object))
  90        (t
  91         (error 'simple-type-error
  92                :datum object
  93                :expected-type '(or symbol
  94                                 ;; KLUDGE: ANSI wants us to
  95                                 ;; return a TYPE-ERROR here, and
  96                                 ;; a TYPE-ERROR is supposed to
  97                                 ;; describe the expected type,
  98                                 ;; but it's not obvious how to
  99                                 ;; describe the coerceable cons
 100                                 ;; types, so we punt and just say
 101                                 ;; CONS. -- WHN 20000503
 102                                 cons)
 103                :format-control "~S can't be coerced to a function."
 104                :format-arguments (list object)))))))
 105
 106 (defun coerce-to-list (object)
 107   (seq-dispatch object
 108                 object
 109                 (vector-to-list* object)
 110                 (sequence-to-list object)))
 111
 112 (defun coerce-to-vector (object output-type-spec)
 113   (etypecase object
 114     (list (list-to-vector* object output-type-spec))
 115     (vector (vector-to-vector* object output-type-spec))))
 116
 117 ;;; old working version
 118 (defun coerce (object output-type-spec)
 119   #!+sb-doc
 120   "Coerce the Object to an object of type Output-Type-Spec."
 121   (declare (explicit-check))
 122   (flet ((coerce-error ()
 123            (declare (optimize allow-non-returning-tail-call))
 124            (error 'simple-type-error
 125                   :format-control "~S can't be converted to type ~
 126                                     ~/sb!impl:print-type-specifier/."
 127                   :format-arguments (list object output-type-spec)
 128                   :datum object
 129                   :expected-type output-type-spec)))
 130     (let ((type (specifier-type output-type-spec)))
 131       (cond
 132         ((%%typep object type)
 133          object)
 134         ((eq type *empty-type*)
 135          (coerce-error))
 136         ((type= type (specifier-type 'character))
 137          (character object))
 138         ((numberp object)
 139          (cond
 140            ((csubtypep type (specifier-type 'single-float))
 141             (let ((res (%single-float object)))
 142               (unless (typep res output-type-spec)
 143                 (coerce-error))
 144               res))
 145            ((csubtypep type (specifier-type 'double-float))
 146             (let ((res (%double-float object)))
 147               (unless (typep res output-type-spec)
 148                 (coerce-error))
 149               res))
 150            #!+long-float
 151            ((csubtypep type (specifier-type 'long-float))
 152             (let ((res (%long-float object)))
 153               (unless (typep res output-type-spec)
 154                 (coerce-error))
 155               res))
 156            ((csubtypep type (specifier-type 'float))
 157             (let ((res (%single-float object)))
 158               (unless (typep res output-type-spec)
 159                 (coerce-error))
 160               res))
 161            (t
 162             (let ((res
 163                    (cond
 164                      ((csubtypep type (specifier-type '(complex single-float)))
 165                       (complex (%single-float (realpart object))
 166                                (%single-float (imagpart object))))
 167                      ((csubtypep type (specifier-type '(complex double-float)))
 168                       (complex (%double-float (realpart object))
 169                                (%double-float (imagpart object))))
 170                      #!+long-float
 171                      ((csubtypep type (specifier-type '(complex long-float)))
 172                       (complex (%long-float (realpart object))
 173                                (%long-float (imagpart object))))
 174                      ((csubtypep type (specifier-type '(complex float)))
 175                       (complex (%single-float (realpart object))
 176                                (%single-float (imagpart object))))
 177                      ((and (typep object 'rational) ; TODO jmoringe unreachable?
 178                            (csubtypep type (specifier-type '(complex float))))
 179                       ;; Perhaps somewhat surprisingly, ANSI specifies
 180                       ;; that (COERCE FOO 'FLOAT) is a SINGLE-FLOAT,
 181                       ;; not dispatching on
 182                       ;; *READ-DEFAULT-FLOAT-FORMAT*.  By analogy, we
 183                       ;; do the same for complex numbers. -- CSR,
 184                       ;; 2002-08-06
 185                       (complex (%single-float object)))
 186                      ((csubtypep type (specifier-type 'complex))
 187                       (complex object))
 188                      (t
 189                       (coerce-error)))))
 190               ;; If RES has the wrong type, that means that rule of
 191               ;; canonical representation for complex rationals was
 192               ;; invoked. According to the Hyperspec, (coerce 7/2
 193               ;; 'complex) returns 7/2. Thus, if the object was a
 194               ;; rational, there is no error here.
 195               (unless (or (typep res output-type-spec)
 196                           (rationalp object))
 197                 (coerce-error))
 198               res))))
 199         ((csubtypep type (specifier-type 'list))
 200          (if (vectorp object)
 201              (cond
 202                ((type= type (specifier-type 'list))
 203                 (vector-to-list* object))
 204                ((type= type (specifier-type 'null))
 205                 (if (= (length object) 0)
 206                     'nil
 207                     (sequence-type-length-mismatch-error type
 208                                                          (length object))))
 209                ((cons-type-p type)
 210                 (multiple-value-bind (min exactp)
 211                     (sb!kernel::cons-type-length-info type)
 212                   (let ((length (length object)))
 213                     (if exactp
 214                         (unless (= length min)
 215                           (sequence-type-length-mismatch-error type length))
 216                         (unless (>= length min)
 217                           (sequence-type-length-mismatch-error type length)))
 218                     (vector-to-list* object))))
 219                (t (sequence-type-too-hairy (type-specifier type))))
 220              (if (sequencep object)
 221                  (cond
 222                    ((type= type (specifier-type 'list))
 223                     (sb!sequence:make-sequence-like
 224                      nil (length object) :initial-contents object))
 225                    ((type= type (specifier-type 'null))
 226                     (if (= (length object) 0)
 227                         'nil
 228                         (sequence-type-length-mismatch-error type
 229                                                              (length object))))
 230                    ((cons-type-p type)
 231                     (multiple-value-bind (min exactp)
 232                         (sb!kernel::cons-type-length-info type)
 233                       (let ((length (length object)))
 234                         (if exactp
 235                             (unless (= length min)
 236                               (sequence-type-length-mismatch-error type length))
 237                             (unless (>= length min)
 238                               (sequence-type-length-mismatch-error type length)))
 239                         (sb!sequence:make-sequence-like
 240                          nil length :initial-contents object))))
 241                    (t (sequence-type-too-hairy (type-specifier type))))
 242                  (coerce-error))))
 243         ((csubtypep type (specifier-type 'vector))
 244          (typecase object
 245            ;; FOO-TO-VECTOR* go through MAKE-SEQUENCE, so length
 246            ;; errors are caught there. -- CSR, 2002-10-18
 247            (list (list-to-vector* object output-type-spec))
 248            (vector (vector-to-vector* object output-type-spec))
 249            (sequence (sequence-to-vector* object output-type-spec))
 250            (t
 251             (coerce-error))))
 252         ((and (csubtypep type (specifier-type 'sequence))
 253               (find-class output-type-spec nil))
 254          (let ((prototype (sb!mop:class-prototype
 255                            (sb!pcl:ensure-class-finalized
 256                             (find-class output-type-spec)))))
 257            (sb!sequence:make-sequence-like
 258             prototype (length object) :initial-contents object)))
 259         ((csubtypep type (specifier-type 'function))
 260          (coerce-to-fun object))
 261         (t
 262          (coerce-error))))))
 263