src/code/describe.lisp

   1 ;;;; most of the DESCRIBE system -- that part which isn't derived
   2 ;;;; from PCL code
   3
   4 ;;;; This software is part of the SBCL system. See the README file for
   5 ;;;; more information.
   6 ;;;;
   7 ;;;; This software is derived from the CMU CL system, which was
   8 ;;;; written at Carnegie Mellon University and released into the
   9 ;;;; public domain. The software is in the public domain and is
  10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  11 ;;;; files for more information.
  12
  13 (in-package "SB-IMPL") ;(SB-IMPL, not SB!IMPL, since we're built in warm load.)
  14 \f
  15 (declaim (ftype (function (t stream)) describe-object))
  16 (defgeneric describe-object (x stream))
  17
  18 (defun describe (x &optional (stream-designator *standard-output*))
  19   #+sb-doc
  20   "Print a description of the object X."
  21   (let ((stream (out-synonym-of stream-designator)))
  22     ;; Until sbcl-0.8.0.x, we did
  23     ;;   (FRESH-LINE STREAM)
  24     ;;   (PPRINT-LOGICAL-BLOCK (STREAM NIL)
  25     ;;     ...
  26     ;; here. However, ANSI's specification of DEFUN DESCRIBE,
  27     ;;   DESCRIBE exists as an interface primarily to manage argument
  28     ;;   defaulting (including conversion of arguments T and NIL into
  29     ;;   stream objects) and to inhibit any return values from
  30     ;;   DESCRIBE-OBJECT.
  31     ;; doesn't mention either FRESH-LINEing or PPRINT-LOGICAL-BLOCKing,
  32     ;; and the example of typical DESCRIBE-OBJECT behavior in ANSI's
  33     ;; specification of DESCRIBE-OBJECT will work poorly if we do them
  34     ;; here. (The example method for DESCRIBE-OBJECT does its own
  35     ;; FRESH-LINEing, which is a physical directive which works poorly
  36     ;; inside a pretty-printer logical block.)
  37     (describe-object x stream)
  38     ;; We don't TERPRI here either (any more since sbcl-0.8.0.x), because
  39     ;; again ANSI's specification of DESCRIBE doesn't mention it and
  40     ;; ANSI's example of DESCRIBE-OBJECT does its own final TERPRI.
  41     )
  42   (values))
  43 \f
  44 ;;;; miscellaneous DESCRIBE-OBJECT methods
  45
  46 (defmethod describe-object ((x t) s)
  47   (format s "~&~@<~S ~_is a ~S.~:>~%" x (type-of x)))
  48
  49 (defmethod describe-object ((x cons) s)
  50   (call-next-method)
  51   (when (and (legal-fun-name-p x)
  52              (fboundp x))
  53     (%describe-fun (fdefinition x) s :function x)
  54     ;;was: (format s "~@:_Its FDEFINITION is ~S.~@:_" (fdefinition x))
  55     ;; TO DO: should check for SETF documentation.
  56     ;; TO DO: should make it clear whether the definition is a
  57     ;; DEFUN (SETF FOO) or DEFSETF FOO or what.
  58     ))
  59
  60 (defmethod describe-object ((x array) s)
  61   (fresh-line s)
  62   (pprint-logical-block (s nil)
  63     (cond
  64      ((= 1 (array-rank x))
  65       (format s "~S is a vector with ~D elements."
  66               x (car (array-dimensions x)))
  67       (when (array-has-fill-pointer-p x)
  68         (format s "~@:_It has a fill pointer value of ~S."
  69                 (fill-pointer x))))
  70      (t
  71       (format s "~S is an array of dimension ~:S."
  72               x (array-dimensions x))))
  73     (let ((array-element-type (array-element-type x)))
  74       (unless (eq array-element-type t)
  75         (format s
  76                 "~@:_Its element type is specialized to ~S."
  77                 array-element-type)))
  78     (if (and (array-header-p x) (%array-displaced-p x))
  79         (format s "~@:_The array is displaced with offset ~S."
  80                 (%array-displacement x))))
  81   (terpri s))
  82
  83 (defmethod describe-object ((x hash-table) s)
  84   (declare (type stream s))
  85   (format s "~&~@<~S ~_is an ~S hash table.~:>" x (hash-table-test x))
  86   (format s "~&Its SIZE is ~S." (hash-table-size x))
  87   (format s
  88           "~&~@<Its REHASH-SIZE is ~S. ~_Its REHASH-THRESHOLD is ~S.~:>"
  89           (hash-table-rehash-size x)
  90           (hash-table-rehash-threshold x))
  91   (fresh-line s)
  92   (pprint-logical-block (s nil)
  93     (let ((count (hash-table-count x)))
  94       (format s "It holds ~S key/value pair~:P~:[: ~2I~_~;.~]"
  95               count (zerop count))
  96       (let ((n 0))
  97         (declare (type index n))
  98         (dohash (k v x)
  99           (unless (zerop n)
 100             (write-char #\space s))
 101           (incf n)
 102           (when (and *print-length* (> n *print-length*))
 103             (format s "~:_...")
 104             (return))
 105           (format s "~:_(~@<~S ~:_~S~:>)" k v)))))
 106   (terpri s))
 107
 108 (defmethod describe-object ((condition condition) s)
 109   (sb-kernel:describe-condition condition s))
 110 \f
 111 ;;;; DESCRIBE-OBJECT methods for symbols and functions, including all
 112 ;;;; sorts of messy stuff about documentation, type information,
 113 ;;;; packaging, function implementation, etc...
 114
 115 ;;; Print the specified kind of documentation about the given NAME. If
 116 ;;; NAME is null, or not a valid name, then don't print anything.
 117 (declaim (ftype (function (t stream t t) (values)) %describe-doc))
 118 (defun %describe-doc (name s kind kind-doc)
 119   (when (and name (typep name '(or symbol cons)))
 120     (let ((doc (fdocumentation name kind)))
 121       (when doc
 122         (format s "~&~@(~A documentation:~)~%  ~A"
 123                 (or kind-doc kind) doc))))
 124   (values))
 125
 126 ;;; Describe various stuff about the functional semantics attached to
 127 ;;; the specified NAME, if NAME is the kind of thing you can look
 128 ;;; up as a name. (In the case of anonymous closures and other
 129 ;;; things, it might not be.) TYPE-SPEC is the function type specifier
 130 ;;; extracted from the definition, or NIL if none.
 131 (declaim (ftype (function (t stream t)) %describe-fun-name))
 132 (defun %describe-fun-name (name s type-spec)
 133   (when (and name (typep name '(or symbol cons)))
 134     (multiple-value-bind (type where)
 135         (if (legal-fun-name-p name)
 136             (values (type-specifier (info :function :type name))
 137                     (info :function :where-from name))
 138             (values type-spec :defined))
 139       (when (consp type)
 140         (format s "~&Its ~(~A~) argument types are:~%  ~S"
 141                 where (second type))
 142         (format s "~&Its result type is:~%  ~S" (third type))))
 143     (let ((inlinep (info :function :inlinep name)))
 144       (when inlinep
 145         (format s
 146                 "~&It is currently declared ~(~A~);~
 147                  ~:[no~;~] expansion is available."
 148                 inlinep (info :function :inline-expansion-designator name))))))
 149
 150 ;;; Print information from the debug-info about where CODE-OBJ was
 151 ;;; compiled from.
 152 (defun %describe-compiled-from (code-obj s)
 153   (declare (type stream s))
 154   (let ((info (sb-kernel:%code-debug-info code-obj)))
 155     (when info
 156       (let ((source (sb-c::debug-info-source info)))
 157         (when source
 158           (format s "~&On ~A it was compiled from:"
 159                   ;; FIXME: The FORMAT-UNIVERSAL-TIME calls in the system
 160                   ;; should become more consistent, probably not using
 161                   ;; any nondefault options.
 162                   (format-universal-time nil (sb-c::debug-source-compiled source)
 163                                          :style :abbreviated))
 164           (let ((name (sb-c::debug-source-name source)))
 165             (ecase (sb-c::debug-source-from source)
 166               (:file
 167                (format s "~&~A~@:_  Created: " (namestring name))
 168                (format-universal-time s (sb-c::debug-source-created source)))
 169               (:lisp (format s "~&  ~S" (aref name 0))))))))))
 170
 171 ;;; Describe a compiled function. The closure case calls us to print
 172 ;;; the guts.
 173 (defun %describe-fun-compiled (x s kind name)
 174   (declare (type stream s))
 175   (let ((args (%simple-fun-arglist x)))
 176     (cond ((not args)
 177            (write-string "  There are no arguments." s))
 178           (t
 179            (format s "~&~@(The ~@[~A's ~]arguments are:~@:_~)" kind)
 180            (write-string "  " s)
 181             (let ((*print-pretty* t)
 182                   (*print-escape* t)
 183                   (*print-base* 10)
 184                   (*print-radix* nil))
 185               (pprint-logical-block (s nil)
 186                  (pprint-indent :current 2)
 187                  (format s "~A" args))))))
 188   (let ((name (or name (%simple-fun-name x))))
 189     (%describe-doc name s 'function kind)
 190     (unless (eq kind :macro)
 191       (%describe-fun-name name s (%simple-fun-type x))))
 192   (%describe-compiled-from (sb-kernel:fun-code-header x) s))
 193
 194 (defun %describe-fun (x s &optional (kind :function) (name nil))
 195   (etypecase x
 196     #+sb-eval
 197     (sb-eval:interpreted-function
 198      (%describe-interpreted-fun x s kind name))
 199     (function
 200      (%describe-compiled-fun x s kind name))))
 201
 202 ;;; Describe a function object. KIND and NAME provide some information
 203 ;;; about where the function came from.
 204 (defun %describe-compiled-fun (x s &optional (kind :function) (name nil))
 205   (declare (type function x))
 206   (declare (type stream s))
 207   (declare (type (member :macro :function) kind))
 208   (fresh-line s)
 209   (pprint-logical-block (s nil)
 210     (ecase kind
 211       (:macro (format s "Macro-function: ~S" x))
 212       (:function (if name
 213                      (format s "Function: ~S" x)
 214                      (format s "~S is a function." x))))
 215     (format s "~@:_~@<Its associated name (as in ~S) is ~2I~_~S.~:>"
 216             'function-lambda-expression
 217             (nth-value 2 (function-lambda-expression x)))
 218     (case (widetag-of x)
 219       (#.sb-vm:closure-header-widetag
 220        (%describe-fun-compiled (%closure-fun x) s kind name)
 221        (format s "~&Its closure environment is:")
 222        (loop for value in (%closure-values x)
 223           for i = 0 then (1+ i)
 224           do (format s "~&  ~S: ~S" i value)))
 225       (#.sb-vm:simple-fun-header-widetag
 226        (%describe-fun-compiled x s kind name))
 227       (#.sb-vm:funcallable-instance-header-widetag
 228        ;; Only STANDARD-GENERIC-FUNCTION would be handled here, but
 229        ;; since it has its own DESCRIBE-OBJECT method, it should've been
 230        ;; picked off before getting here. So hopefully we never get here.
 231        (format s "~@:_It is an unknown type of funcallable instance."))
 232       (t
 233        (format s "~@:_It is an unknown type of function."))))
 234   (terpri s))
 235
 236 ;; Describe an interpreted function.
 237 #+sb-eval
 238 (defun %describe-interpreted-fun (x s &optional (kind :function) (name nil))
 239   (declare (type sb-eval:interpreted-function x))
 240   (declare (type stream s))
 241   (declare (type (member :macro :function) kind))
 242   (fresh-line s)
 243   (pprint-logical-block (s nil)
 244     (ecase kind
 245       (:macro (format s "Macro-function: ~S" x))
 246       (:function (if name
 247                      (format s "Function: ~S" x)
 248                      (format s "~S is a function." x))))
 249     (format s "~@:_~@<Its associated name (as in ~S) is ~2I~_~S.~:>"
 250             'function-lambda-expression
 251             (nth-value 2 (function-lambda-expression x)))
 252     (format s "~&It is an interpreted function.~%")
 253     (let ((args (sb-eval:interpreted-function-lambda-list x)))
 254       (cond ((not args)
 255              (write-string "There are no arguments." s))
 256             (t
 257              (format s "~&~@(The ~@[~A's ~]arguments are:~@:_~)" kind)
 258              (write-string "  " s)
 259              (let ((*print-pretty* t)
 260                    (*print-escape* t)
 261                    (*print-base* 10)
 262                    (*print-radix* nil))
 263                (pprint-logical-block (s nil)
 264                  (pprint-indent :current 2)
 265                  (format s "~A" args)))))
 266       (format s "~&It was defined as: ")
 267       (let ((*print-pretty* t)
 268             (*print-escape* t)
 269             (*print-base* 10)
 270             (*print-radix* nil))
 271         (pprint-logical-block (s nil)
 272           (pprint-indent :current 2)
 273           (format s "~A" (function-lambda-expression x))))))
 274   (terpri s))
 275
 276 (defmethod describe-object ((x function) s)
 277   (%describe-fun x s :function))
 278
 279 (defgeneric describe-symbol-fdefinition (function stream &key name))
 280
 281 (defmethod describe-symbol-fdefinition ((fun function) stream &key name)
 282   (%describe-fun fun stream :function name))
 283
 284 (defmethod describe-symbol-fdefinition ((fun standard-generic-function) stream
 285                                         &key name)
 286   (declare (ignore name))
 287   ;; Just delegate.
 288   (describe-object fun stream))
 289
 290 (defmethod describe-object ((x symbol) s)
 291   (declare (type stream s))
 292
 293   ;; Describe the packaging.
 294   (let ((package (symbol-package x)))
 295     (if package
 296         (multiple-value-bind (symbol status)
 297             (find-symbol (symbol-name x) package)
 298           (declare (ignore symbol))
 299           (format s "~&~@<~S is ~_an ~(~A~) symbol ~_in ~S.~:>"
 300                   x status (symbol-package x)))
 301         (format s "~&~@<~S is ~_an uninterned symbol.~:>" x)))
 302   ;; TO DO: We could grovel over all packages looking for and
 303   ;; reporting other phenomena, e.g. IMPORT and SHADOW, or
 304   ;; availability in some package even after (SYMBOL-PACKAGE X) has
 305   ;; been set to NIL.
 306
 307   ;; Describe the value cell.
 308   (let* ((kind (info :variable :kind x))
 309          (wot (ecase kind
 310                 (:special "special variable")
 311                 (:macro "symbol macro")
 312                 (:constant "constant")
 313                 (:global "undefined variable")
 314                 (:alien nil))))
 315     (pprint-logical-block (s nil)
 316       (cond
 317        ((eq kind :alien)
 318         (let ((info (info :variable :alien-info x)))
 319           (format s "~&~@<It is an alien at #X~8,'0X of type ~3I~:_~S.~:>"
 320                   (sap-int (eval (sb-alien::heap-alien-info-sap-form info)))
 321                   (sb-alien-internals:unparse-alien-type
 322                    (sb-alien::heap-alien-info-type info)))
 323           (format s "~&~@<Its current value is ~3I~:_~S.~:>"
 324                   (eval x))))
 325        ((eq kind :macro)
 326         (let ((expansion (info :variable :macro-expansion x)))
 327           (format s "~&It is a ~A with expansion ~S." wot expansion)))
 328        ((boundp x)
 329         (format s "~&~@<It is a ~A; its ~_value is ~S.~:>"
 330                 wot (symbol-value x)))
 331        ((not (eq kind :global))
 332         (format s "~&~@<It is a ~A; no current value.~:>" wot)))
 333
 334       (when (eq (info :variable :where-from x) :declared)
 335         (format s "~&~@<Its declared type ~_is ~S.~:>"
 336                 (type-specifier (info :variable :type x)))))
 337
 338     (%describe-doc x s 'variable kind))
 339
 340   ;; Print out properties.
 341   (format s "~@[~&Its SYMBOL-PLIST is ~@<~2I~_~S~:>.~]" (symbol-plist x))
 342
 343   ;; Describe the function cell.
 344   (cond ((macro-function x)
 345          (%describe-fun (macro-function x) s :macro x))
 346         ((special-operator-p x)
 347          (%describe-doc x s :function "Special form"))
 348         ((fboundp x)
 349          (describe-symbol-fdefinition (fdefinition x) s :name x)))
 350
 351   ;; Print other documentation.
 352   (%describe-doc x s 'structure "Structure")
 353   (%describe-doc x s 'type "Type")
 354   (%describe-doc x s 'setf "Setf macro")
 355   (dolist (assoc (info :random-documentation :stuff x))
 356     (format s
 357             "~&~@<Documentation on the ~(~A~):~@:_~A~:>"
 358             (car assoc)
 359             (cdr assoc)))
 360
 361   ;; Mention the associated type information, if any.
 362   ;;
 363   ;; As of sbcl-0.7.2, (INFO :TYPE :KIND X) might be
 364   ;;   * :PRIMITIVE, which is handled by the FIND-CLASS case.
 365   ;;   * :DEFINED, which is handled specially.
 366   ;;   * :INSTANCE, which is handled by the FIND-CLASS case.
 367   ;;   * :FORTHCOMING-DEFCLASS-TYPE, which is an internal-to-the-compiler
 368   ;;     note that we don't try to report.
 369   ;;   * NIL, in which case there's nothing to see here, move along.
 370   (when (eq (info :type :kind x) :defined)
 371     (format s "~&It names a type specifier."))
 372   (let ((symbol-named-class (find-class x nil)))
 373     (when symbol-named-class
 374       (format s "~&It names a class ~A." symbol-named-class)
 375       (describe symbol-named-class s)))
 376
 377   (terpri s))