src/code/symbol.lisp

   1 ;;;; code to manipulate symbols (but not packages, which are handled
   2 ;;;; elsewhere)
   3 ;;;;
   4 ;;;; Many of these definitions are trivial interpreter entries to
   5 ;;;; functions open-coded by the compiler.
   6
   7 ;;;; This software is part of the SBCL system. See the README file for
   8 ;;;; more information.
   9 ;;;;
  10 ;;;; This software is derived from the CMU CL system, which was
  11 ;;;; written at Carnegie Mellon University and released into the
  12 ;;;; public domain. The software is in the public domain and is
  13 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  14 ;;;; files for more information.
  15
  16 (in-package "SB!IMPL")
  17
  18 (declaim (maybe-inline get get2 get3 %put getf remprop %putf get-properties keywordp))
  19
  20 (defun symbol-value (symbol)
  21   #!+sb-doc
  22   "Return SYMBOL's current bound value."
  23   (declare (optimize (safety 1)))
  24   (symbol-value symbol))
  25
  26 (defun boundp (symbol)
  27   #!+sb-doc
  28   "Return non-NIL if SYMBOL is bound to a value."
  29   (boundp symbol))
  30
  31 (defun set (symbol new-value)
  32   #!+sb-doc
  33   "Set SYMBOL's value cell to NEW-VALUE."
  34   (declare (type symbol symbol))
  35   (about-to-modify-symbol-value symbol "set SYMBOL-VALUE of ~S" new-value)
  36   (%set-symbol-value symbol new-value))
  37
  38 (defun %set-symbol-value (symbol new-value)
  39   (%set-symbol-value symbol new-value))
  40
  41 (declaim (inline %makunbound))
  42 (defun %makunbound (symbol)
  43   (%set-symbol-value symbol (%primitive sb!c:make-other-immediate-type
  44                                         0 sb!vm:unbound-marker-widetag)))
  45
  46 (defun makunbound (symbol)
  47   #!+sb-doc
  48   "Make SYMBOL unbound, removing any value it may currently have."
  49   (with-single-package-locked-error (:symbol symbol "unbinding the symbol ~A")
  50     (about-to-modify-symbol-value symbol "make ~S unbound")
  51     (%makunbound symbol)
  52     symbol))
  53
  54 ;;; Return the built-in hash value for SYMBOL.
  55 (defun symbol-hash (symbol)
  56   (symbol-hash symbol))
  57
  58 (defun symbol-function (symbol)
  59   #!+sb-doc
  60   "Return SYMBOL's current function definition. Settable with SETF."
  61   (%coerce-name-to-fun symbol))
  62
  63 (defun (setf symbol-function) (new-value symbol)
  64   (declare (type symbol symbol) (type function new-value))
  65   (with-single-package-locked-error
  66       (:symbol symbol "setting the symbol-function of ~A")
  67     (setf (%coerce-name-to-fun symbol) new-value)))
  68
  69 (defun symbol-plist (symbol)
  70   #!+sb-doc
  71   "Return SYMBOL's property list."
  72   (symbol-plist symbol))
  73
  74 (defun %set-symbol-plist (symbol new-value)
  75   (setf (symbol-plist symbol) new-value))
  76
  77 (defun symbol-name (symbol)
  78   #!+sb-doc
  79   "Return SYMBOL's name as a string."
  80   (symbol-name symbol))
  81
  82 (defun symbol-package (symbol)
  83   #!+sb-doc
  84   "Return the package SYMBOL was interned in, or NIL if none."
  85   (symbol-package symbol))
  86
  87 (defun %set-symbol-package (symbol package)
  88   (declare (type symbol symbol))
  89   (%set-symbol-package symbol package))
  90
  91 (defun make-symbol (string)
  92   #!+sb-doc
  93   "Make and return a new symbol with the STRING as its print name."
  94   (declare (type string string))
  95   (%make-symbol (if (simple-string-p string)
  96                     string
  97                     (subseq string 0))))
  98
  99 (defun get (symbol indicator &optional (default nil))
 100   #!+sb-doc
 101   "Look on the property list of SYMBOL for the specified INDICATOR. If this
 102   is found, return the associated value, else return DEFAULT."
 103   (get3 symbol indicator default))
 104
 105 (defun get2 (symbol indicator)
 106   (get3 symbol indicator nil))
 107 #|
 108   (let (cdr-pl)
 109     (do ((pl (symbol-plist symbol) (cdr cdr-pl)))
 110         ((atom pl) nil)
 111       (setf cdr-pl (cdr pl))
 112       (cond ((atom cdr-pl)
 113              (error "~S has an odd number of items in its property list."
 114                     symbol))
 115             ((eq (car pl) indicator)
 116              (return (car cdr-pl)))))))
 117 |#
 118
 119 (defun get3 (symbol indicator default)
 120   (let (cdr-pl)
 121     (do ((pl (symbol-plist symbol) (cdr cdr-pl)))
 122         ((atom pl) default)
 123       (setq cdr-pl (cdr pl))
 124       (cond ((atom cdr-pl)
 125              (error "~S has an odd number of items in its property list."
 126                     symbol))
 127             ((eq (car pl) indicator)
 128              (return (car cdr-pl)))))))
 129
 130 (defun %put (symbol indicator value)
 131   #!+sb-doc
 132   "The VALUE is added as a property of SYMBOL under the specified INDICATOR.
 133   Returns VALUE."
 134   (do ((pl (symbol-plist symbol) (cddr pl)))
 135       ((endp pl)
 136        (setf (symbol-plist symbol)
 137              (list* indicator value (symbol-plist symbol)))
 138        value)
 139     (cond ((endp (cdr pl))
 140            (error "~S has an odd number of items in its property list."
 141                   symbol))
 142           ((eq (car pl) indicator)
 143            (rplaca (cdr pl) value)
 144            (return value)))))
 145
 146 (defun remprop (symbol indicator)
 147   #!+sb-doc
 148   "Look on property list of SYMBOL for property with specified
 149   INDICATOR. If found, splice this indicator and its value out of
 150   the plist, and return the tail of the original list starting with
 151   INDICATOR. If not found, return () with no side effects.
 152
 153   NOTE: The ANSI specification requires REMPROP to return true (not false)
 154   or false (the symbol NIL). Portable code should not rely on any other value."
 155   (do ((pl (symbol-plist symbol) (cddr pl))
 156        (prev nil pl))
 157       ((atom pl) nil)
 158     (cond ((atom (cdr pl))
 159            (error "~S has an odd number of items in its property list."
 160                   symbol))
 161           ((eq (car pl) indicator)
 162            (cond (prev (rplacd (cdr prev) (cddr pl)))
 163                  (t
 164                   (setf (symbol-plist symbol) (cddr pl))))
 165            (return pl)))))
 166
 167 (defun getf (place indicator &optional (default ()))
 168   #!+sb-doc
 169   "Search the property list stored in Place for an indicator EQ to INDICATOR.
 170   If one is found, return the corresponding value, else return DEFAULT."
 171   (do ((plist place (cddr plist)))
 172       ((null plist) default)
 173     (cond ((atom (cdr plist))
 174            (error 'simple-type-error
 175                   :format-control "malformed property list: ~S."
 176                   :format-arguments (list place)
 177                   :datum (cdr plist)
 178                   :expected-type 'cons))
 179           ((eq (car plist) indicator)
 180            (return (cadr plist))))))
 181
 182 (defun %putf (place property new-value)
 183   (declare (type list place))
 184   (do ((plist place (cddr plist)))
 185       ((endp plist) (list* property new-value place))
 186     (declare (type list plist))
 187     (when (eq (car plist) property)
 188       (setf (cadr plist) new-value)
 189       (return place))))
 190
 191 (defun get-properties (place indicator-list)
 192   #!+sb-doc
 193   "Like GETF, except that INDICATOR-LIST is a list of indicators which will
 194   be looked for in the property list stored in PLACE. Three values are
 195   returned, see manual for details."
 196   (do ((plist place (cddr plist)))
 197       ((null plist) (values nil nil nil))
 198     (cond ((atom (cdr plist))
 199            (error 'simple-type-error
 200                   :format-control "malformed property list: ~S."
 201                   :format-arguments (list place)
 202                   :datum (cdr plist)
 203                   :expected-type 'cons))
 204           ((memq (car plist) indicator-list)
 205            (return (values (car plist) (cadr plist) plist))))))
 206
 207 (defun copy-symbol (symbol &optional (copy-props nil) &aux new-symbol)
 208   #!+sb-doc
 209   "Make and return a new uninterned symbol with the same print name
 210   as SYMBOL. If COPY-PROPS is false, the new symbol is neither bound
 211   nor fbound and has no properties, else it has a copy of SYMBOL's
 212   function, value and property list."
 213   (declare (type symbol symbol))
 214   (setq new-symbol (make-symbol (symbol-name symbol)))
 215   (when copy-props
 216     (%set-symbol-value new-symbol
 217                        (%primitive sb!c:fast-symbol-value symbol))
 218     (setf (symbol-plist new-symbol)
 219           (copy-list (symbol-plist symbol)))
 220     (when (fboundp symbol)
 221       (setf (symbol-function new-symbol) (symbol-function symbol))))
 222   new-symbol)
 223
 224 ;;; FIXME: This declaration should be redundant.
 225 (declaim (special *keyword-package*))
 226
 227 (defun keywordp (object)
 228   #!+sb-doc
 229   "Return true if Object is a symbol in the \"KEYWORD\" package."
 230   (and (symbolp object)
 231        (eq (symbol-package object) *keyword-package*)))
 232 \f
 233 ;;;; GENSYM and friends
 234
 235 (defvar *gensym-counter* 0
 236   #!+sb-doc
 237   "counter for generating unique GENSYM symbols")
 238 (declaim (type unsigned-byte *gensym-counter*))
 239
 240 (defun gensym (&optional (thing "G"))
 241   #!+sb-doc
 242   "Creates a new uninterned symbol whose name is a prefix string (defaults
 243    to \"G\"), followed by a decimal number. Thing, when supplied, will
 244    alter the prefix if it is a string, or be used for the decimal number
 245    if it is a number, of this symbol. The default value of the number is
 246    the current value of *gensym-counter* which is incremented each time
 247    it is used."
 248   (let ((old *gensym-counter*))
 249     (unless (numberp thing)
 250       (let ((new (etypecase old
 251                    (index (1+ old))
 252                    (unsigned-byte (1+ old)))))
 253         (declare (optimize (speed 3) (safety 0)(inhibit-warnings 3)))
 254         (setq *gensym-counter* new)))
 255     (multiple-value-bind (prefix int)
 256         (etypecase thing
 257           (simple-string (values thing old))
 258           (fixnum (values "G" thing))
 259           (string (values (coerce thing 'simple-string) old)))
 260       (declare (simple-string prefix))
 261       (make-symbol
 262        (concatenate 'simple-string prefix
 263                     (the simple-string
 264                          (quick-integer-to-string int)))))))
 265
 266 (defvar *gentemp-counter* 0)
 267 (declaim (type unsigned-byte *gentemp-counter*))
 268
 269 (defun gentemp (&optional (prefix "T") (package (sane-package)))
 270   #!+sb-doc
 271   "Creates a new symbol interned in package PACKAGE with the given PREFIX."
 272   (declare (type string prefix))
 273   (loop
 274     (let ((*print-base* 10)
 275           (*print-radix* nil)
 276           (*print-pretty* nil)
 277           (new-pname (format nil "~A~D" prefix (incf *gentemp-counter*))))
 278       (multiple-value-bind (symbol existsp) (find-symbol new-pname package)
 279         (declare (ignore symbol))
 280         (unless existsp (return (values (intern new-pname package))))))))