;;;; some stuff for displaying information for debugging/experimenting
;;;; with the system, mostly conditionalized with #!+SB-SHOW

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.

(in-package "SB!INT")

;;;; various SB-SHOW-dependent forms
;;;;
;;;; In general, macros named /FOO
;;;;   * are for debugging/tracing
;;;;   * expand into nothing unless :SB-SHOW is in the target
;;;;     features list
;;;; Often, they also do nothing at runtime if */SHOW* is NIL, but
;;;; this is not always true for some very-low-level ones.
;;;;
;;;; (I follow the "/FOO for debugging/tracing expressions" naming
;;;; rule and several other naming conventions in all my Lisp
;;;; programming when possible, and then set Emacs to display comments
;;;; in one shade of blue, tracing expressions in another shade of
;;;; blue, and declarations and assertions in a yellowish shade, so
;;;; that it's easy to separate them from the "real code" which
;;;; actually does the work of the program. -- WHN 2001-05-07)

;;; Set this to NIL to suppress output from /SHOW-related forms.
#!+sb-show (defvar */show* t)

#!+sb-show
(defun cannot-/show (string)
  (declare (type simple-string string))
  #+sb-xc-host (error "can't /SHOW: ~A" string)
  ;; We end up in this situation when we execute /SHOW too early in
  ;; cold init. That happens to me often enough that it's really
  ;; annoying for it to cause a hard failure -- which at that point is
  ;; hard to recover from -- instead of just diagnostic output.
  #-sb-xc-host
  (progn (%primitive print
          (concatenate 'simple-base-string
                       "/can't /SHOW:" (the simple-base-string string)))
         t))

;;; Should /SHOW output be suppressed at this point?
;;;
;;; Note that despite the connoting-no-side-effects-pure-predicate
;;; name, we emit some error output if we're called at a point where
;;; /SHOW is inherently invalid.
#!+sb-show
(defun suppress-/show-p ()
         ;; protection against /SHOW too early in cold init for
         ;; (FORMAT *TRACE-OUTPUT* ..) to work, part I: Obviously
         ;; we need *TRACE-OUTPUT* bound.
  (if (not (boundp '*trace-output*))
      (cannot-/show "*TRACE-OUTPUT* isn't bound. (Try /SHOW0.)")
         ;; ordinary, healthy reason to suppress /SHOW, no error
         ;; output needed. Assume by default _not_ to suppress.
      (and (boundp '*/show*) (not */show*))))

;;; shorthand for a common idiom in output statements used in
;;; debugging: (/SHOW "Case 2:" X Y) becomes a pretty-printed version
;;; of (FORMAT .. "~&/Case 2: X=~S Y=~S~%" X Y), conditional on */SHOW*.
(defmacro /show (&rest xlist)
  #!-sb-show (declare (ignore xlist))
  #!+sb-show
  (flet (;; Is X something we want to just show literally by itself?
         ;; (instead of showing it as NAME=VALUE)
         (literal-p (x) (or (stringp x) (numberp x))))
    ;; We build a FORMAT statement out of what we find in XLIST.
    (let ((format-stream (make-string-output-stream)) ; string arg to FORMAT
          (format-reverse-rest)  ; reversed &REST argument to FORMAT
          (first-p t))            ; first pass through loop?
      (write-string "~&~<~;/" format-stream)
      (dolist (x xlist)
        (if first-p
            (setq first-p nil)
            (write-string #+ansi-cl " ~_"
                          #-ansi-cl " " ; for CLISP (CLTL1-ish)
                          format-stream))
        (if (literal-p x)
            (princ x format-stream)
            (progn (let ((*print-pretty* nil))
                     (format format-stream "~S=~~S" x))
                   (push x format-reverse-rest))))
      (write-string "~;~:>~%" format-stream)
      (let ((format-string (get-output-stream-string format-stream))
            (format-rest (reverse format-reverse-rest)))
        `(locally
           (declare (optimize (speed 1) (space 2) (safety 3)))
           (unless (suppress-/show-p)
             (format *trace-output*
                     ,format-string
                     #+ansi-cl (list ,@format-rest)
                     #-ansi-cl ,@format-rest)) ; for CLISP (CLTL1-ish)
           (values))))))

;;; a disabled-at-compile-time /SHOW, implemented as a macro instead
;;; of a function so that leaving occasionally-useful /SHOWs in place
;;; but disabled incurs no run-time overhead and works even when the
;;; arguments can't be evaluated (e.g. because they're only meaningful
;;; in a debugging version of the system, or just due to bit rot..)
(defmacro /noshow (&rest rest)
  (declare (ignore rest)))

;;; like /SHOW, except displaying values in hexadecimal
(defmacro /xhow (&rest rest)
  `(let ((*print-base* 16))
     (/show ,@rest)))
(defmacro /noxhow (&rest rest)
  (declare (ignore rest)))

;;; a trivial version of /SHOW which only prints a constant string,
;;; implemented at a sufficiently low level that it can be used early
;;; in cold init
;;;
;;; Unlike the other /SHOW-related functions, this one doesn't test
;;; */SHOW* at runtime, because messing with special variables early
;;; in cold load is too much trouble to be worth it.
(defmacro /show0 (&rest string-designators)
  ;; We can't use inline MAPCAR here because, at least in 0.6.11.x,
  ;; this code gets compiled before DO-ANONYMOUS is defined.
  ;; Similarly, we don't use inline CONCATENATE, because some of the
  ;; machinery behind its optimizations isn't available in the
  ;; cross-compiler.
  (declare (notinline mapcar concatenate))
  (let ((s (apply #'concatenate
                  'simple-string
                  (mapcar #'string string-designators))))
    (declare (ignorable s)) ; (for when #!-SB-SHOW)
    #+sb-xc-host `(/show ,s)
    #-sb-xc-host `(progn
                    #!+sb-show
                    (%primitive print
                                ,(concatenate 'simple-string "/" s)))))
(defmacro /noshow0 (&rest rest)
  (declare (ignore rest)))

;;; low-level display of a string, works even early in cold init
(defmacro /primitive-print (thing)
  (declare (ignorable thing)) ; (for when #!-SB-SHOW)
  #!+sb-show
  (progn
    #+sb-xc-host `(/show "(/primitive-print)" ,thing)
    #-sb-xc-host `(%primitive print (the simple-string ,thing))))

;;; low-level display of a system word, works even early in cold init
(defmacro /hexstr (thing)
  (declare (ignorable thing)) ; (for when #!-SB-SHOW)
  #!+sb-show
  (progn
    #+sb-xc-host `(/show "(/hexstr)" ,thing)
    #-sb-xc-host `(%primitive print (hexstr ,thing))))

(defmacro /nohexstr (thing)
  (declare (ignore thing)))

(/show0 "done with show.lisp")
