src/code/inspect.lisp

   1 ;;;; the CL:INSPECT function
   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") ;(SB-IMPL, not SB!IMPL, since we're built in warm load.)
  13
  14 (defparameter *inspect-length* 10)
  15
  16 ;;; When *INSPECT-UNBOUND-OBJECT-MARKER* occurs in a parts list, it
  17 ;;; indicates that that a slot is unbound.
  18 (defvar *inspect-unbound-object-marker* (gensym "INSPECT-UNBOUND-OBJECT-"))
  19
  20 (defun inspector (object input-stream output-stream)
  21   (declare (ignore input-stream))
  22   (catch 'quit-inspect
  23     (%inspect object output-stream))
  24   (values))
  25
  26 (defvar *inspect-fun* #'inspector
  27   "a function of three arguments OBJECT, INPUT, and OUTPUT which starts an interactive inspector.")
  28
  29 (defvar *inspected*)
  30 (setf (documentation '*inspected* 'variable)
  31       "the value currently being inspected in CL:INSPECT")
  32
  33 (defun inspect (object)
  34   (funcall *inspect-fun* object *standard-input* *standard-output*))
  35
  36 (defvar *help-for-inspect*
  37   "
  38 help for INSPECT:
  39   Q, E        -  Quit the inspector.
  40   <integer>   -  Inspect the numbered slot.
  41   R           -  Redisplay current inspected object.
  42   U           -  Move upward/backward to previous inspected object.
  43   ?, H, Help  -  Show this help.
  44   <other>     -  Evaluate the input as an expression.
  45 Within the inspector, the special variable SB-EXT:*INSPECTED* is bound
  46 to the current inspected object, so that it can be referred to in
  47 evaluated expressions.
  48 ")
  49
  50 (defun %inspect (*inspected* s)
  51   (named-let redisplay () ; "LAMBDA, the ultimate GOTO":-|
  52     (multiple-value-bind (description named-p elements)
  53         (inspected-parts *inspected*)
  54       (tty-display-inspected-parts description named-p elements s)
  55       (named-let reread ()
  56         (format s "~&> ")
  57         (force-output)
  58         (let* (;; newly-consed object for hermetic protection against
  59                ;; mischievous input like #.*EOF-OBJECT*:
  60                (eof (cons *eof-object* nil))
  61                (command (read *standard-input* nil eof)))
  62           (when (eq command eof)
  63              ;; currently-undocumented feature: EOF is handled as Q.
  64              ;; If there's ever consensus that this is *the* right
  65              ;; thing to do (as opposed to e.g. handling it as U), we
  66              ;; could document it. Meanwhile, it seems more Unix-y to
  67              ;; do this than to signal an error.
  68              (/show0 "THROWing QUIT-INSPECT for EOF")
  69              (throw 'quit-inspect nil))
  70           (typecase command
  71             (integer
  72              (let ((elements-length (length elements)))
  73                (cond ((< -1 command elements-length)
  74                       (let* ((element (nth command elements))
  75                              (value (if named-p (cdr element) element)))
  76                         (cond ((eq value *inspect-unbound-object-marker*)
  77                                (format s "~%That slot is unbound.~%")
  78                                (return-from %inspect (reread)))
  79                               (t
  80                                (%inspect value s)
  81                                ;; If we ever return, then we should be
  82                                ;; looking at *INSPECTED* again.
  83                                (return-from %inspect (redisplay))))))
  84                      ((zerop elements-length)
  85                       (format s "~%The object contains nothing to inspect.~%")
  86                       (return-from %inspect (reread)))
  87                      (t
  88                       (format s "~%Enter a valid index (~:[0-~W~;0~]).~%"
  89                               (= elements-length 1) (1- elements-length))
  90                       (return-from %inspect (reread))))))
  91             (symbol
  92              (case (find-symbol (symbol-name command) *keyword-package*)
  93                ((:q :e)
  94                 (/show0 "THROWing QUIT-INSPECT for :Q or :E")
  95                 (throw 'quit-inspect nil))
  96                (:u
  97                 (return-from %inspect))
  98                (:r
  99                 (return-from %inspect (redisplay)))
 100                ((:h :? :help)
 101                 (write-string *help-for-inspect* s)
 102                 (return-from %inspect (reread)))
 103                (t
 104                 (eval-for-inspect command s)
 105                 (return-from %inspect (reread)))))
 106             (t
 107              (eval-for-inspect command s)
 108              (return-from %inspect (reread)))))))))
 109
 110 (defun eval-for-inspect (command stream)
 111   (let ((result-list (restart-case (multiple-value-list (eval command))
 112                        (nil () :report "Return to the inspector."
 113                           (format stream "~%returning to the inspector~%")
 114                           (return-from eval-for-inspect nil)))))
 115     ;; FIXME: Much of this interactive-EVAL logic is shared with
 116     ;; the main REPL EVAL and with the debugger EVAL. The code should
 117     ;; be shared explicitly.
 118     (setf /// // // / / result-list)
 119     (setf +++ ++ ++ + + - - command)
 120     (setf *** ** ** * * (car /))
 121     (format stream "~&~{~S~%~}" /)))
 122
 123 (defun tty-display-inspected-parts (description named-p elements stream)
 124   (format stream "~%~A" description)
 125   (let ((index 0))
 126     (dolist (element elements)
 127       (if named-p
 128           (destructuring-bind (name . value) element
 129             (format stream "~W. ~A: ~W~%" index name
 130                     (if (eq value *inspect-unbound-object-marker*)
 131                         "unbound"
 132                         value)))
 133           (format stream "~W. ~W~%" index element))
 134       (incf index))))
 135 \f
 136 ;;;; INSPECTED-PARTS
 137
 138 ;;; Destructure an object for inspection, returning
 139 ;;;   (VALUES DESCRIPTION NAMED-P ELEMENTS),
 140 ;;; where..
 141 ;;;
 142 ;;;   DESCRIPTION is a summary description of the destructured object,
 143 ;;;   e.g. "The object is a CONS.~%".
 144 ;;;
 145 ;;;   NAMED-P determines what representation is used for elements
 146 ;;;   of ELEMENTS. If NAMED-P is true, then each element is
 147 ;;;   (CONS NAME VALUE); otherwise each element is just VALUE.
 148 ;;;
 149 ;;;   ELEMENTS is a list of the component parts of OBJECT (whose
 150 ;;;   representation is determined by NAMED-P).
 151 ;;;
 152 ;;; (The NAMED-P dichotomy is useful because symbols and instances
 153 ;;; need to display both a slot name and a value, while lists and
 154 ;;; vectors need only display a value.)
 155 (defgeneric inspected-parts (object))
 156
 157 (defmethod inspected-parts ((object symbol))
 158   (values (format nil "The object is a SYMBOL.~%")
 159           t
 160           (list (cons "Name" (symbol-name object))
 161                 (cons "Package" (symbol-package object))
 162                 (cons "Value" (if (boundp object)
 163                                   (symbol-value object)
 164                                   *inspect-unbound-object-marker*))
 165                 (cons "Function" (if (fboundp object)
 166                                      (symbol-function object)
 167                                      *inspect-unbound-object-marker*))
 168                 (cons "Plist" (symbol-plist object)))))
 169
 170 (defun inspected-structure-elements (object)
 171   (let ((parts-list '())
 172         (info (layout-info (sb-kernel:layout-of object))))
 173     (when (sb-kernel::defstruct-description-p info)
 174       (dolist (dd-slot (dd-slots info) (nreverse parts-list))
 175         (push (cons (dsd-name dd-slot)
 176                     (funcall (dsd-accessor-name dd-slot) object))
 177               parts-list)))))
 178
 179 (defmethod inspected-parts ((object structure-object))
 180   (values (format nil "The object is a STRUCTURE-OBJECT of type ~S.~%"
 181                   (type-of object))
 182           t
 183           (inspected-structure-elements object)))
 184
 185 (defun inspected-standard-object-elements (object)
 186   (let ((reversed-elements nil)
 187         (class-slots (sb-pcl::class-slots (class-of object))))
 188     (dolist (class-slot class-slots (nreverse reversed-elements))
 189       (let* ((slot-name (slot-value class-slot 'sb-pcl::name))
 190              (slot-value (if (slot-boundp object slot-name)
 191                              (slot-value object slot-name)
 192                              *inspect-unbound-object-marker*)))
 193         (push (cons slot-name slot-value) reversed-elements)))))
 194
 195 (defmethod inspected-parts ((object standard-object))
 196   (values (format nil "The object is a STANDARD-OBJECT of type ~S.~%"
 197                   (type-of object))
 198           t
 199           (inspected-standard-object-elements object)))
 200
 201 (defmethod inspected-parts ((object sb-mop:funcallable-standard-object))
 202   (values (format nil "The object is a ~S of type ~S.~%"
 203                   'sb-mop:funcallable-standard-object (type-of object))
 204           t
 205           (inspected-standard-object-elements object)))
 206
 207 (defmethod inspected-parts ((object condition))
 208   (values (format nil "The object is a CONDITION of type ~S.~%"
 209                   (type-of object))
 210           t
 211           (inspected-standard-object-elements object)))
 212
 213 (defmethod inspected-parts ((object function))
 214   (values (format nil "The object is a ~A named ~S.~%"
 215                   (if (closurep object) 'closure 'function)
 216                   (nth-value 2 (function-lambda-expression object)))
 217           t
 218           ;; Defined-from stuff used to be here. Someone took
 219           ;; it out. FIXME: We should make it easy to get
 220           ;; to DESCRIBE from the inspector.
 221           (list*
 222            (cons "Lambda-list" (%fun-lambda-list object))
 223            (cons "Ftype" (%fun-type object))
 224            (when (closurep object)
 225              (list
 226               (cons "Closed over values" (%closure-values object)))))))
 227
 228 #+sb-eval
 229 (defmethod inspected-parts ((object sb-eval:interpreted-function))
 230   (values (format nil "The object is an interpreted function named ~S.~%"
 231                   (nth-value 2 (function-lambda-expression object)))
 232           t
 233           ;; Defined-from stuff used to be here. Someone took
 234           ;; it out. FIXME: We should make it easy to get
 235           ;; to DESCRIBE from the inspector.
 236           (list
 237            (cons "Lambda-list" (sb-eval:interpreted-function-lambda-list object))
 238            (cons "Definition" (function-lambda-expression object))
 239            (cons "Documentation" (sb-eval:interpreted-function-documentation object)))))
 240
 241 (defmethod inspected-parts ((object vector))
 242   (values (format nil
 243                   "The object is a ~:[~;displaced ~]VECTOR of length ~W.~%"
 244                   (and (array-header-p object)
 245                        (%array-displaced-p object))
 246                   (length object))
 247           nil
 248           ;; FIXME: Should we respect *INSPECT-LENGTH* here? If not, what
 249           ;; does *INSPECT-LENGTH* mean?
 250           (coerce object 'list)))
 251
 252 (defun inspected-index-string (index rev-dimensions)
 253   (if (null rev-dimensions)
 254       "[]"
 255       (let ((list nil))
 256         (dolist (dim rev-dimensions)
 257           (multiple-value-bind (q r) (floor index dim)
 258             (setq index q)
 259             (push r list)))
 260         (format nil "[~W~{,~W~}]" (car list) (cdr list)))))
 261
 262 (defmethod inspected-parts ((object array))
 263   (let* ((length (min (array-total-size object) *inspect-length*))
 264          (reference-array (make-array length
 265                                       :element-type (array-element-type object)
 266                                       :displaced-to object))
 267          (dimensions (array-dimensions object))
 268          (reversed-elements nil))
 269     ;; FIXME: Should we respect *INSPECT-LENGTH* here? If not, what does
 270     ;; *INSPECT-LENGTH* mean?
 271     (dotimes (i length)
 272       (push (cons (format nil
 273                           "~A "
 274                           (inspected-index-string i (reverse dimensions)))
 275                   (aref reference-array i))
 276             reversed-elements))
 277     (values (format nil "The object is ~:[a displaced~;an~] ARRAY of ~A.~%~
 278                          Its dimensions are ~S.~%"
 279                     (array-element-type object)
 280                     (and (array-header-p object)
 281                          (%array-displaced-p object))
 282                     dimensions)
 283             t
 284             (nreverse reversed-elements))))
 285
 286 (defmethod inspected-parts ((object cons))
 287   (if (consp (cdr object))
 288       (inspected-parts-of-nontrivial-list object)
 289       (inspected-parts-of-simple-cons object)))
 290
 291 (defun inspected-parts-of-simple-cons (object)
 292   (values "The object is a CONS.
 293 "
 294           t
 295           (list (cons 'car (car object))
 296                 (cons 'cdr (cdr object)))))
 297
 298 (defun inspected-parts-of-nontrivial-list (object)
 299   (let ((length 0)
 300         (in-list object)
 301         (reversed-elements nil))
 302     (flet ((done (description-format)
 303              (return-from inspected-parts-of-nontrivial-list
 304                (values (format nil description-format length)
 305                        t
 306                        (nreverse reversed-elements)))))
 307       (loop
 308        (cond ((null in-list)
 309               (done "The object is a proper list of length ~S.~%"))
 310              ((>= length *inspect-length*)
 311               (push (cons 'rest in-list) reversed-elements)
 312               (done "The object is a long list (more than ~S elements).~%"))
 313              ((consp in-list)
 314               (push (cons length (pop in-list)) reversed-elements)
 315               (incf length))
 316              (t
 317               (push (cons 'rest in-list) reversed-elements)
 318               (done "The object is an improper list of length ~S.~%")))))))
 319
 320 (defmethod inspected-parts ((object t))
 321   (values (format nil "The object is an ATOM:~%  ~W~%" object) nil nil))