procyberian/emacs
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

cl-print: handle circular objects when `print-circle' is nil (Bug#27117)

Browse source 
* lisp/emacs-lisp/cl-print.el (cl-print--currently-printing): New variable.
(cl-print-object): When `print-circle' is nil, bind it to a list of
objects that are currently printing to avoid printing the same object
endlessly.
* test/lisp/emacs-lisp/cl-print-tests.el (cl-print-circle): New test.
This commit is contained in:
Noam Postavsky 2017-05-28 17:01:05 -04:00
parent 94306c8b0d
commit a415c8bccb
2 changed files with 32 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

35
lisp/emacs-lisp/cl-print.el
View file

@ -37,6 +37,7 @@
"If non-nil, try and make sure the result can be `read'.")
(defvar cl-print--number-table nil)
(defvar cl-print--currently-printing nil)
;;;###autoload
(cl-defgeneric cl-print-object (object stream)
@ -59,8 +60,9 @@ call other entry points instead, such as `cl-prin1'."
(princ "(" stream)
(cl-print-object car stream)
(while (and (consp object)
(not (and cl-print--number-table
(numberp (gethash object cl-print--number-table)))))
(not (if cl-print--number-table
(numberp (gethash object cl-print--number-table))
(memq object cl-print--currently-printing))))
(princ " " stream)
(cl-print-object (pop object) stream))
(when object
@ -156,15 +158,26 @@ call other entry points instead, such as `cl-prin1'."
(cl-defmethod cl-print-object :around (object stream)
;; FIXME: Only put such an :around method on types where it's relevant.
(let ((n (if cl-print--number-table (gethash object cl-print--number-table))))
(if (not (numberp n))
(cl-call-next-method)
(if (> n 0)
;; Already printed. Just print a reference.
(progn (princ "#" stream) (princ n stream) (princ "#" stream))
(puthash object (- n) cl-print--number-table)
(princ "#" stream) (princ (- n) stream) (princ "=" stream)
(cl-call-next-method)))))
(cond
(print-circle
(let ((n (gethash object cl-print--number-table)))
(if (not (numberp n))
(cl-call-next-method)
(if (> n 0)
;; Already printed. Just print a reference.
(progn (princ "#" stream) (princ n stream) (princ "#" stream))
(puthash object (- n) cl-print--number-table)
(princ "#" stream) (princ (- n) stream) (princ "=" stream)
(cl-call-next-method)))))
((let ((already-printing (memq object cl-print--currently-printing)))
(when already-printing
;; Currently printing, just print reference to avoid endless
;; recursion.
(princ "#" stream)
(princ (length (cdr already-printing)) stream))))
(t (let ((cl-print--currently-printing
(cons object cl-print--currently-printing)))
(cl-call-next-method)))))
(defvar cl-print--number-index nil)