python-mode loops on if/else

[Montanaro]

(migrating from python project)

Original submission:

Here's how to reproduce. Create a .py file in XEmacs
 containing this text:

 x = (if 1: 2
  ____else: 3)

 (except that the ____ really means four spaces).

 Now position your cursor somewhere inside those 4
 spaces, and hit TAB. XEmacs freezes until you hit
^G.

Followup comments:

Date: 2003-07-31 22:41
Sender: montanaro
Logged In: YES
user_id=44345

The code gets into an infloop in py-outdent-p. The
loop looks
odd to me:

  (while (or (looking-at py-blank-or-comment-re)
                (bobp))
     (backward-to-indentation 1))

If you were at (bobp), why would you want to try to
move back
a line?

[http://sourceforge.net/tracker/index.php?func=detail&aid=783240&group_id=86916&atid=581349]

[Mark-byers (mark-byers)]

I can confirm this bug.

The following two line file also causes an infinite loop:

a
else:

When the colon is typed, the inifinite loop is triggered.

I think the following change fixes the problem:

- (while (or (looking-at py-blank-or-comment-re)
- (bobp))
+ (while (and (looking-at py-blank-or-comment-re)
+ (not (bobp)))
                  (backward-to-indentation 1))

[Mark-byers (mark-byers)]

Here is a patch file. I wasn't sure how to attach it as a
file, so here it is in plain text. It seems that the 'short
circuit infloop on illegal construct' line is no longer
needed so I have removed it.

--- python-mode/python-mode.el 2005-02-20 14:23:58.000000000
+0100
+++ python-mode/python-mode.el.new 2005-02-20
14:29:05.319602112 +0100
@@ -1239,13 +1239,11 @@
   (save-excursion
     (and (progn (back-to-indentation)
   (looking-at py-outdent-re))
- ;; short circuit infloop on illegal construct
- (not (bobp))
   (progn (forward-line -1)
   (py-goto-initial-line)
   (back-to-indentation)
- (while (or (looking-at py-blank-or-comment-re)
- (bobp))
+ (while (and (looking-at py-blank-or-comment-re)
+ (not (bobp)))
     (backward-to-indentation 1))
   (not (looking-at py-no-outdent-re)))
   )))

[Andreas Roehler (a-roehler)]

Hi Skip,

get an syntax-errror

   File "<ipython console>", line 1
     x = (if 1: 2)
           ^
SyntaxError: invalid syntax

###########

When changing the form all is fine.
Do you still experience a freeze from TAB?

Andreas

[Andreas Roehler (a-roehler)]

Hi,

as the form pointed at looks insane in any case, will change that.

Thanks

Andreas