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Title: expose html.parser.unescape
Type: enhancement Stage: resolved
Components: Library (Lib) Versions: Python 3.4
Status: closed Resolution: fixed
Dependencies: Superseder:
Assigned To: ezio.melotti Nosy List: BreamoreBoy, brett.cannon, ezio.melotti, martin.panter, python-dev, rnk, serhiy.storchaka, thomaspinckney3, vstinner
Priority: normal Keywords: needs review, patch

Created on 2008-05-20 05:43 by thomaspinckney3, last changed 2022-04-11 14:56 by admin. This issue is now closed.

File name Uploaded Description Edit
unescape.diff thomaspinckney3, 2008-05-20 05:43 review
unescape.diff thomaspinckney3, 2010-11-09 00:25 review
issue2927.diff ezio.melotti, 2013-11-18 09:23 review
issue2927-2.diff ezio.melotti, 2013-11-19 12:31 review
issue2927-3.diff ezio.melotti, 2013-11-19 17:41 review
Messages (14)
msg67102 - (view) Author: Tom Pinckney (thomaspinckney3) * Date: 2008-05-20 05:43
There is currently a private method inside of html.parser.HTMLParser to 
unescape HTML &...; style escapes. This would be useful to expose for 
other users who want to unescape a piece of HTML.

Additionally, many websites don't use proper unicode or iso-8859-1 
encodings and accidentally use Microsoft Code Page 1252 extensions. I 
added code to map these to their appropriate unicode values.

The unescaping logic was slightly simplified too.

This is my first Python patch submission, so please let me know if I've 
done anything wrong.

A new test case was also added for this functionality.
msg67103 - (view) Author: Brett Cannon (brett.cannon) * (Python committer) Date: 2008-05-20 05:47
The plan is to add html.escape(). Adding html.unescape() wouldn't hurt.
msg110636 - (view) Author: Mark Lawrence (BreamoreBoy) * Date: 2010-07-18 11:46
Trying to run the test and I get:-

c:\py3k\Lib>..\PCbuild\python_d.exe test\
  File "test\", line 326
    escaped = u"<p>There&#146;s the C&ocirc;te</p>"
SyntaxError: invalid syntax
msg110657 - (view) Author: Reid Kleckner (rnk) (Python committer) Date: 2010-07-18 15:38
It's using the old Python 2 unicode string literal syntax.

It also doesn't keep to 80 cols.

I'd also rather continue using a lazily initialized dict instead of catching a KeyError for &apos;.

I also feel that with the changes to Unicode in py3k, the cp1252 stuff won't work as desired and should be cut.


Is anyone still interested in html.unescape or html.escape anyway?  Every web framework seems to have their own support routines already.  Otherwise I'd recommend close -> wontfix.
msg111461 - (view) Author: Mark Lawrence (BreamoreBoy) * Date: 2010-07-24 11:48
msg110657 recommends close -> wontfix.  Does anybody want this kept open or can it be closed?
msg111566 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2010-07-25 22:30
I'm not sure that using an hardcoded mapping CP1252 => unicode is a good idea.
msg120269 - (view) Author: Tom Pinckney (thomaspinckney3) * Date: 2010-11-02 22:32
I don't think Django includes an HTML unescape. I'm not familiar with other frameworks. So I'd still find this useful to include in the stdlib.
msg120826 - (view) Author: Tom Pinckney (thomaspinckney3) * Date: 2010-11-09 00:25
New patch attached, tested against Python 3.2. This is my first Python patch so apologies if I've done something wrong here. Feedback appreciated!


* fit everything to 80 cols
* just made changes to the HTMLParser.unescape function instead of providing a standalone unescape function
* fixed test case to fix string literals to work in python 3k
* left the cp1252 hacks in there since it looks like they work still, but if there's a problem with them let me know. In practice I have to this at work in order to make unescaping actual web pages work.
msg203341 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * (Python committer) Date: 2013-11-19 07:39
I added comments on Rietveld.

Yet one thing. For now the html module is very simple and has no dependencies. The patch adds an import of re and html.escapes and relative heavy re.compile operations. Due to the fact that the html module is implicitly imported when any of the html submodules is imported, this can affect a code which doesn't use unescape(). However a cure for this problem (lazy import and initialization) may be worse than the problem itself, perhaps we should live with it.
msg203369 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2013-11-19 12:31
Here's an updated patch that addresses comments on rietveld and adds a few more tests and docs.
I should also update the what's new, but I have other upcoming changes in the html package so I'll probably do it at the end.

Regarding your concern:
* if people are only using html.escape, then they will get a couple of extra imports, including all the html5 entities, and a re.compile;
* if people are using html.parser, they already have plenty of re.compiles there, and soon html.parser will use unescape too;
* if people are using html.entities they only get an extra re.compile;

Overall I don't think it's a big problem.

As a side node, the "if '&' in s:" in the unescape function could be removed -- I'm not sure it brings any real advantage.  This could/should be proved by benchmarks.
msg203403 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2013-11-19 17:41
Here is the last iteration with a few minor tweaks and a couple more tests.
msg203410 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * (Python committer) Date: 2013-11-19 18:27
msg203413 - (view) Author: Roundup Robot (python-dev) (Python triager) Date: 2013-11-19 18:29
New changeset 7b9235852b3b by Ezio Melotti in branch 'default':
#2927: Added the unescape() function to the html module.
msg203415 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2013-11-19 18:51
Fixed, thanks for the reviews!
Date User Action Args
2022-04-11 14:56:34adminsetgithub: 47176
2013-11-19 18:51:50ezio.melottisetstatus: open -> closed
resolution: fixed
messages: + msg203415

stage: commit review -> resolved
2013-11-19 18:29:15python-devsetnosy: + python-dev
messages: + msg203413
2013-11-19 18:27:13serhiy.storchakasetmessages: + msg203410
2013-11-19 17:41:17ezio.melottisetfiles: + issue2927-3.diff

messages: + msg203403
stage: patch review -> commit review
2013-11-19 12:31:39ezio.melottisetfiles: + issue2927-2.diff

messages: + msg203369
2013-11-19 07:39:05serhiy.storchakasetnosy: + serhiy.storchaka
messages: + msg203341
2013-11-18 10:40:10ezio.melottilinkissue13633 dependencies
2013-11-18 09:54:25ezio.melottilinkissue513840 superseder
2013-11-18 09:23:21ezio.melottisetfiles: + issue2927.diff
assignee: ezio.melotti
versions: + Python 3.4, - Python 3.2
2012-11-28 03:37:33martin.pantersetnosy: + martin.panter
2010-11-09 00:25:44thomaspinckney3setfiles: + unescape.diff

messages: + msg120826
2010-11-02 22:32:55thomaspinckney3setmessages: + msg120269
2010-07-25 22:30:19vstinnersetmessages: + msg111566
2010-07-24 11:51:42eric.araujosetstatus: pending -> open
nosy: + vstinner, ezio.melotti

versions: + Python 3.2, - Python 2.7
2010-07-24 11:48:33BreamoreBoysetstatus: open -> pending

messages: + msg111461
2010-07-18 15:38:58rnksetnosy: + rnk
messages: + msg110657
2010-07-18 11:46:56BreamoreBoysetnosy: + BreamoreBoy
messages: + msg110636
2010-01-15 20:32:20brian.curtinsetpriority: normal
keywords: + needs review
stage: patch review
versions: + Python 2.7, - Python 2.6
2008-05-20 05:47:55brett.cannonsetnosy: + brett.cannon
messages: + msg67103
2008-05-20 05:43:53thomaspinckney3create