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 %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)
  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 (defun makunbound (symbol)
  42   #!+sb-doc
  43   "Make SYMBOL unbound, removing any value it may currently have."
  44   (set symbol
  45        (%primitive sb!c:make-other-immediate-type
  46                    0
  47                    sb!vm:unbound-marker-widetag))
  48   symbol)
  49
  50 ;;; Return the built-in hash value for SYMBOL.
  51
  52 ;;; only backends for which a SYMBOL-HASH vop exists.  In the past,
  53 ;;; when the MIPS backend supported (or nearly did) a generational
  54 ;;; (non-conservative) garbage collector, this read (OR X86 MIPS).
  55 ;;; Having excised the vestigial support for GENGC, this now only
  56 ;;; applies for the x86 port, but if someone were to rework the GENGC
  57 ;;; support, this might change again.  -- CSR, 2002-08-26
  58 #!+x86
  59 (defun symbol-hash (symbol)
  60   (symbol-hash symbol))
  61
  62 ;;; Compute the hash value for SYMBOL.
  63 #!-x86
  64 (defun symbol-hash (symbol)
  65   (%sxhash-simple-string (symbol-name symbol)))
  66
  67 (defun symbol-function (symbol)
  68   #!+sb-doc
  69   "Return SYMBOL's current function definition. Settable with SETF."
  70   (%coerce-name-to-fun symbol))
  71
  72 (defun (setf symbol-function) (new-value symbol)
  73   (declare (type symbol symbol) (type function new-value))
  74   (setf (%coerce-name-to-fun symbol) new-value))
  75
  76 (defun symbol-plist (symbol)
  77   #!+sb-doc
  78   "Return SYMBOL's property list."
  79   (symbol-plist symbol))
  80
  81 (defun %set-symbol-plist (symbol new-value)
  82   (setf (symbol-plist symbol) new-value))
  83
  84 (defun symbol-name (symbol)
  85   #!+sb-doc
  86   "Return SYMBOL's name as a string."
  87   (symbol-name symbol))
  88
  89 (defun symbol-package (symbol)
  90   #!+sb-doc
  91   "Return the package SYMBOL was interned in, or NIL if none."
  92   (symbol-package symbol))
  93
  94 (defun %set-symbol-package (symbol package)
  95   (declare (type symbol symbol))
  96   (%set-symbol-package symbol package))
  97
  98 (defun make-symbol (string)
  99   #!+sb-doc
 100   "Make and return a new symbol with the STRING as its print name."
 101   (make-symbol string))
 102
 103 (defun get (symbol indicator &optional (default nil))
 104   #!+sb-doc
 105   "Look on the property list of SYMBOL for the specified INDICATOR. If this
 106   is found, return the associated value, else return DEFAULT."
 107   (do ((pl (symbol-plist symbol) (cddr pl)))
 108       ((atom pl) default)
 109     (cond ((atom (cdr pl))
 110            (error "~S has an odd number of items in its property list."
 111                    symbol))
 112           ((eq (car pl) indicator)
 113            (return (cadr pl))))))
 114
 115 (defun %put (symbol indicator value)
 116   #!+sb-doc
 117   "The VALUE is added as a property of SYMBOL under the specified INDICATOR.
 118   Returns VALUE."
 119   (do ((pl (symbol-plist symbol) (cddr pl)))
 120       ((endp pl)
 121        (setf (symbol-plist symbol)
 122              (list* indicator value (symbol-plist symbol)))
 123        value)
 124     (cond ((endp (cdr pl))
 125            (error "~S has an odd number of items in its property list."
 126                   symbol))
 127           ((eq (car pl) indicator)
 128            (rplaca (cdr pl) value)
 129            (return value)))))
 130
 131 (defun remprop (symbol indicator)
 132   #!+sb-doc
 133   "Look on property list of SYMBOL for property with specified
 134   INDICATOR. If found, splice this indicator and its value out of
 135   the plist, and return the tail of the original list starting with
 136   INDICATOR. If not found, return () with no side effects.
 137
 138   NOTE: The ANSI specification requires REMPROP to return true (not false)
 139   or false (the symbol NIL). Portable code should not rely on any other value."
 140   (do ((pl (symbol-plist symbol) (cddr pl))
 141        (prev nil pl))
 142       ((atom pl) nil)
 143     (cond ((atom (cdr pl))
 144            (error "~S has an odd number of items in its property list."
 145                   symbol))
 146           ((eq (car pl) indicator)
 147            (cond (prev (rplacd (cdr prev) (cddr pl)))
 148                  (t
 149                   (setf (symbol-plist symbol) (cddr pl))))
 150            (return pl)))))
 151
 152 (defun getf (place indicator &optional (default ()))
 153   #!+sb-doc
 154   "Search the property list stored in Place for an indicator EQ to INDICATOR.
 155   If one is found, return the corresponding value, else return DEFAULT."
 156   (do ((plist place (cddr plist)))
 157       ((null plist) default)
 158     (cond ((atom (cdr plist))
 159            (error "~S is a malformed property list."
 160                   place))
 161           ((eq (car plist) indicator)
 162            (return (cadr plist))))))
 163
 164 (defun %putf (place property new-value)
 165   (declare (type list place))
 166   (do ((plist place (cddr plist)))
 167       ((endp plist) (list* property new-value place))
 168     (declare (type list plist))
 169     (when (eq (car plist) property)
 170       (setf (cadr plist) new-value)
 171       (return place))))
 172
 173 (defun get-properties (place indicator-list)
 174   #!+sb-doc
 175   "Like GETF, except that INDICATOR-LIST is a list of indicators which will
 176   be looked for in the property list stored in PLACE. Three values are
 177   returned, see manual for details."
 178   (do ((plist place (cddr plist)))
 179       ((null plist) (values nil nil nil))
 180     (cond ((atom (cdr plist))
 181            (error "~S is a malformed proprty list."
 182                   place))
 183           ((memq (car plist) indicator-list)
 184            (return (values (car plist) (cadr plist) plist))))))
 185
 186 (defun copy-symbol (symbol &optional (copy-props nil) &aux new-symbol)
 187   #!+sb-doc
 188   "Make and return a new uninterned symbol with the same print name
 189   as SYMBOL. If COPY-PROPS is false, the new symbol is neither bound
 190   nor fbound and has no properties, else it has a copy of SYMBOL's
 191   function, value and property list."
 192   (declare (type symbol symbol))
 193   (setq new-symbol (make-symbol (symbol-name symbol)))
 194   (when copy-props
 195     (%set-symbol-value new-symbol
 196                        (%primitive sb!c:fast-symbol-value symbol))
 197     (setf (symbol-plist new-symbol)
 198           (copy-list (symbol-plist symbol)))
 199     (when (fboundp symbol)
 200       (setf (symbol-function new-symbol) (symbol-function symbol))))
 201   new-symbol)
 202
 203 ;;; FIXME: This declaration should be redundant.
 204 (declaim (special *keyword-package*))
 205
 206 (defun keywordp (object)
 207   #!+sb-doc
 208   "Return true if Object is a symbol in the \"KEYWORD\" package."
 209   (and (symbolp object)
 210        (eq (symbol-package object) *keyword-package*)))
 211 \f
 212 ;;;; GENSYM and friends
 213
 214 (defvar *gensym-counter* 0
 215   #!+sb-doc
 216   "counter for generating unique GENSYM symbols")
 217 (declaim (type unsigned-byte *gensym-counter*))
 218
 219 (defun gensym (&optional (thing "G"))
 220   #!+sb-doc
 221   "Creates a new uninterned symbol whose name is a prefix string (defaults
 222    to \"G\"), followed by a decimal number. Thing, when supplied, will
 223    alter the prefix if it is a string, or be used for the decimal number
 224    if it is a number, of this symbol. The default value of the number is
 225    the current value of *gensym-counter* which is incremented each time
 226    it is used."
 227   (let ((old *gensym-counter*))
 228     (unless (numberp thing)
 229       (let ((new (etypecase old
 230                    (index (1+ old))
 231                    (unsigned-byte (1+ old)))))
 232         (declare (optimize (speed 3) (safety 0)(inhibit-warnings 3)))
 233         (setq *gensym-counter* new)))
 234     (multiple-value-bind (prefix int)
 235         (etypecase thing
 236           (simple-string (values thing old))
 237           (fixnum (values "G" thing))
 238           (string (values (coerce thing 'simple-string) old)))
 239       (declare (simple-string prefix))
 240       (make-symbol
 241        (concatenate 'simple-string prefix
 242                     (the simple-string
 243                          (quick-integer-to-string int)))))))
 244
 245 (defvar *gentemp-counter* 0)
 246 (declaim (type unsigned-byte *gentemp-counter*))
 247
 248 (defun gentemp (&optional (prefix "T") (package (sane-package)))
 249   #!+sb-doc
 250   "Creates a new symbol interned in package PACKAGE with the given PREFIX."
 251   (declare (type string prefix))
 252   (loop
 253     (let ((*print-base* 10)
 254           (*print-radix* nil)
 255           (*print-pretty* nil)
 256           (new-pname (format nil "~A~D" prefix (incf *gentemp-counter*))))
 257       (multiple-value-bind (symbol existsp) (find-symbol new-pname package)
 258         (declare (ignore symbol))
 259         (unless existsp (return (values (intern new-pname package))))))))