61 lines
1.7 KiB
Plaintext
61 lines
1.7 KiB
Plaintext
|
From: dalke at bioreason.com (Andrew Dalke)
|
||
|
|
Date: Sun, 25 Apr 1999 19:14:51 -0600
|
||
|
|
Subject: Handling backspace chars in a string...
|
||
|
|
References: <37239c48.594910176@news2.bga.com>
|
||
|
|
Message-ID: <3723BE0B.EFEC289A@bioreason.com>
|
||
|
|
Content-Length: 1466
|
||
|
|
X-UID: 148
|
||
|
|
|
||
|
|
bwizard at bga.com (Purple) said:
|
||
|
|
> I'm in the posistion of having to process strings with arbitrary
|
||
|
|
> numbers of backspace and newline characters in them. The backspaces
|
||
|
|
> actually get put in the string, so I have to handle removing the
|
||
|
|
> characters that are backspaced over.
|
||
|
|
>
|
||
|
|
> [one implementation given]
|
||
|
|
>
|
||
|
|
> This just looked rather messy to me -- I was curious if anyone know
|
||
|
|
> a better way?
|
||
|
|
|
||
|
|
Here's one possibility. It uses a regular expression substitution
|
||
|
|
to replace <any character> + <backspace> with the empty string.
|
||
|
|
(Note: don't use a raw string for the re; r".\b" will find a character
|
||
|
|
which is before a word break.) When done, it removes all the
|
||
|
|
leading backspaces.
|
||
|
|
|
||
|
|
|
||
|
|
import re
|
||
|
|
char_backspace = re.compile(".\b") # Don't use a raw string here
|
||
|
|
any_backspaces = re.compile("\b+") # or here
|
||
|
|
|
||
|
|
def apply_backspaces(s):
|
||
|
|
while 1:
|
||
|
|
t = char_backspace.sub("", s)
|
||
|
|
if len(s) == len(t):
|
||
|
|
# remove any backspaces which may start a line
|
||
|
|
return any_backspaces.sub("", t)
|
||
|
|
s = t
|
||
|
|
|
||
|
|
|
||
|
|
>>> apply_backspaces("\bQ\b\bAndqt\b\brew Dalkt\br\be")
|
||
|
|
'Andrew Dalke'
|
||
|
|
|
||
|
|
|
||
|
|
You mentioned something about containing newlines. By default, the
|
||
|
|
"." re pattern doesn't match a \n, so the above code acts like a
|
||
|
|
normal tty, and doesn't remove the \n if followed by a newline. This
|
||
|
|
is likely the right thing. That's also why I delete any backspace
|
||
|
|
because
|
||
|
|
"this\n\bthat"
|
||
|
|
|
||
|
|
should be the same string as
|
||
|
|
"this
|
||
|
|
that"
|
||
|
|
|
||
|
|
Andrew Dalke
|
||
|
|
dalke at acm.org
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|