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 (;; KMP idiom, using stream itself as EOF value
  59               (command (read *standard-input* nil *standard-input*)))
  60           (typecase command
  61             (stream ; i.e. EOF
  62              ;; currently-undocumented feature: EOF is handled as Q.
  63              ;; If there's ever consensus that this is *the* right
  64              ;; thing to do (as opposed to e.g. handling it as U), we
  65              ;; could document it. Meanwhile, it seems more Unix-y to
  66              ;; do this than to signal an error.
  67              (/show0 "THROWing QUIT-INSPECT for EOF")
  68              (throw 'quit-inspect nil))
  69             (integer
  70              (let ((elements-length (length elements)))
  71                (cond ((< -1 command elements-length)
  72                       (let* ((element (nth command elements))
  73                              (value (if named-p (cdr element) element)))
  74                         (cond ((eq value *inspect-unbound-object-marker*)
  75                                (format s "~%That slot is unbound.~%")
  76                                (return-from %inspect (reread)))
  77                               (t
  78                                (%inspect value s)
  79                                ;; If we ever return, then we should be
  80                                ;; looking at *INSPECTED* again.
  81                                (return-from %inspect (redisplay))))))
  82                      ((zerop elements-length)
  83                       (format s "~%The object contains nothing to inspect.~%")
  84                       (return-from %inspect (reread)))
  85                      (t
  86                       (format s "~%Enter a valid index (~:[0-~W~;0~]).~%"
  87                               (= elements-length 1) (1- elements-length))
  88                       (return-from %inspect (reread))))))
  89             (symbol
  90              (case (find-symbol (symbol-name command) *keyword-package*)
  91                ((:q :e)
  92                 (/show0 "THROWing QUIT-INSPECT for :Q or :E")
  93                 (throw 'quit-inspect nil))
  94                (:u
  95                 (return-from %inspect))
  96                (:r
  97                 (return-from %inspect (redisplay)))
  98                ((:h :? :help)
  99                 (write-string *help-for-inspect* s)
 100                 (return-from %inspect (reread)))
 101                (t
 102                 (eval-for-inspect command s)
 103                 (return-from %inspect (reread)))))
 104             (t
 105              (eval-for-inspect command s)
 106              (return-from %inspect (reread)))))))))
 107
 108 (defun eval-for-inspect (command stream)
 109   (let ((result-list (restart-case (multiple-value-list (eval command))
 110                        (nil () :report "Return to the inspector."
 111                           (format stream "~%returning to the inspector~%")
 112                           (return-from eval-for-inspect nil)))))
 113     ;; FIXME: Much of this interactive-EVAL logic is shared with
 114     ;; the main REPL EVAL and with the debugger EVAL. The code should
 115     ;; be shared explicitly.
 116     (setf /// // // / / result-list)
 117     (setf +++ ++ ++ + + - - command)
 118     (setf *** ** ** * * (car /))
 119     (format stream "~&~{~S~%~}" /)))
 120
 121 (defun tty-display-inspected-parts (description named-p elements stream)
 122   (format stream "~%~A" description)
 123   (let ((index 0))
 124     (dolist (element elements)
 125       (if named-p
 126           (destructuring-bind (name . value) element
 127             (format stream "~W. ~A: ~W~%" index name
 128                     (if (eq value *inspect-unbound-object-marker*)
 129                         "unbound"
 130                         value)))
 131           (format stream "~W. ~W~%" index element))
 132       (incf index))))
 133 \f
 134 ;;;; INSPECTED-PARTS
 135
 136 ;;; Destructure an object for inspection, returning
 137 ;;;   (VALUES DESCRIPTION NAMED-P ELEMENTS),
 138 ;;; where..
 139 ;;;
 140 ;;;   DESCRIPTION is a summary description of the destructured object,
 141 ;;;   e.g. "The object is a CONS.~%".
 142 ;;;
 143 ;;;   NAMED-P determines what representation is used for elements
 144 ;;;   of ELEMENTS. If NAMED-P is true, then each element is
 145 ;;;   (CONS NAME VALUE); otherwise each element is just VALUE.
 146 ;;;
 147 ;;;   ELEMENTS is a list of the component parts of OBJECT (whose
 148 ;;;   representation is determined by NAMED-P).
 149 ;;;
 150 ;;; (The NAMED-P dichotomy is useful because symbols and instances
 151 ;;; need to display both a slot name and a value, while lists and
 152 ;;; vectors need only display a value.)
 153 (defgeneric inspected-parts (object))
 154
 155 (defmethod inspected-parts ((object symbol))
 156   (values (format nil "The object is a SYMBOL.~%" object)
 157           t
 158           (list (cons "Name" (symbol-name object))
 159                 (cons "Package" (symbol-package object))
 160                 (cons "Value" (if (boundp object)
 161                                   (symbol-value object)
 162                                   *inspect-unbound-object-marker*))
 163                 (cons "Function" (if (fboundp object)
 164                                      (symbol-function object)
 165                                      *inspect-unbound-object-marker*))
 166                 (cons "Plist" (symbol-plist object)))))
 167
 168 (defun inspected-structure-elements (object)
 169   (let ((parts-list '())
 170         (info (layout-info (sb-kernel:layout-of object))))
 171     (when (sb-kernel::defstruct-description-p info)
 172       (dolist (dd-slot (dd-slots info) (nreverse parts-list))
 173         (push (cons (dsd-%name dd-slot)
 174                     (funcall (dsd-accessor-name dd-slot) object))
 175               parts-list)))))
 176
 177 (defmethod inspected-parts ((object structure-object))
 178   (values (format nil "The object is a STRUCTURE-OBJECT of type ~S.~%"
 179                   (type-of object))
 180           t
 181           (inspected-structure-elements object)))
 182
 183 (defun inspected-standard-object-elements (object)
 184   (let ((reversed-elements nil)
 185         (class-slots (sb-pcl::class-slots (class-of object))))
 186     (dolist (class-slot class-slots (nreverse reversed-elements))
 187       (let* ((slot-name (slot-value class-slot 'sb-pcl::name))
 188              (slot-value (if (slot-boundp object slot-name)
 189                              (slot-value object slot-name)
 190                              *inspect-unbound-object-marker*)))
 191         (push (cons slot-name slot-value) reversed-elements)))))
 192
 193 (defmethod inspected-parts ((object standard-object))
 194   (values (format nil "The object is a STANDARD-OBJECT of type ~S.~%"
 195                   (type-of object))
 196           t
 197           (inspected-standard-object-elements object)))
 198
 199 (defmethod inspected-parts ((object funcallable-instance))
 200   (values (format nil "The object is a FUNCALLABLE-INSTANCE of type ~S.~%"
 201                   (type-of object))
 202           t
 203           (inspected-structure-elements object)))
 204
 205 (defmethod inspected-parts ((object function))
 206   (let* ((type (sb-kernel:widetag-of object))
 207          (object (if (= type sb-vm:closure-header-widetag)
 208                      (sb-kernel:%closure-fun object)
 209                      object)))
 210     (values (format nil "FUNCTION ~S.~@[~%Argument List: ~A~]." object
 211                     (sb-kernel:%simple-fun-arglist object)
 212                     ;; Defined-from stuff used to be here. Someone took
 213                     ;; it out. FIXME: We should make it easy to get
 214                     ;; to DESCRIBE from the inspector.
 215                     )
 216             t
 217             nil)))
 218
 219 (defmethod inspected-parts ((object vector))
 220   (values (format nil
 221                   "The object is a ~:[~;displaced ~]VECTOR of length ~W.~%"
 222                   (and (array-header-p object)
 223                        (%array-displaced-p object))
 224                   (length object))
 225           nil
 226           ;; FIXME: Should we respect *INSPECT-LENGTH* here? If not, what
 227           ;; does *INSPECT-LENGTH* mean?
 228           (coerce object 'list)))
 229
 230 (defun inspected-index-string (index rev-dimensions)
 231   (if (null rev-dimensions)
 232       "[]"
 233       (let ((list nil))
 234         (dolist (dim rev-dimensions)
 235           (multiple-value-bind (q r) (floor index dim)
 236             (setq index q)
 237             (push r list)))
 238         (format nil "[~W~{,~W~}]" (car list) (cdr list)))))
 239
 240 (defmethod inspected-parts ((object array))
 241   (let* ((length (min (array-total-size object) *inspect-length*))
 242          (reference-array (make-array length :displaced-to object))
 243          (dimensions (array-dimensions object))
 244          (reversed-elements nil))
 245     ;; FIXME: Should we respect *INSPECT-LENGTH* here? If not, what does
 246     ;; *INSPECT-LENGTH* mean?
 247     (dotimes (i length)
 248       (push (cons (format nil
 249                           "~A "
 250                           (inspected-index-string i (reverse dimensions)))
 251                   (aref reference-array i))
 252             reversed-elements))
 253     (values (format nil "The object is ~:[a displaced~;an~] ARRAY of ~A.~%~
 254                          Its dimensions are ~S.~%"
 255                     (array-element-type object)
 256                     (and (array-header-p object)
 257                          (%array-displaced-p object))
 258                     dimensions)
 259             t
 260             (nreverse reversed-elements))))
 261
 262 (defmethod inspected-parts ((object cons))
 263   (if (consp (cdr object))
 264       (inspected-parts-of-nontrivial-list object)
 265       (inspected-parts-of-simple-cons object)))
 266
 267 (defun inspected-parts-of-simple-cons (object)
 268   (values "The object is a CONS.
 269 "
 270           t
 271           (list (cons 'car (car object))
 272                 (cons 'cdr (cdr object)))))
 273
 274 (defun inspected-parts-of-nontrivial-list (object)
 275   (let ((length 0)
 276         (in-list object)
 277         (reversed-elements nil))
 278     (flet ((done (description-format)
 279              (return-from inspected-parts-of-nontrivial-list
 280                (values (format nil description-format length)
 281                        t
 282                        (nreverse reversed-elements)))))
 283       (loop
 284        (cond ((null in-list)
 285               (done "The object is a proper list of length ~S.~%"))
 286              ((>= length *inspect-length*)
 287               (push (cons 'rest in-list) reversed-elements)
 288               (done "The object is a long list (more than ~S elements).~%"))
 289              ((consp in-list)
 290               (push (cons length (pop in-list)) reversed-elements)
 291               (incf length))
 292              (t
 293               (push (cons 'rest in-list) reversed-elements)
 294               (done "The object is an improper list of length ~S.~%")))))))
 295
 296 (defmethod inspected-parts ((object t))
 297   (values (format nil "The object is an ATOM:~%  ~W~%" object) nil nil))