PR: Fix several code snippets corner cases

[andfoy]

Description of Changes

This PR addresses all of the code snippets errors reported on #10230

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)

• Included a screenshot or animation (if affecting the UI, see Licecap)

Issue(s) Resolved

Fixes #10289.
Fixes #10230

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct:
@andfoy

[andfoy]

@ccordoba12 @dalthviz, does this PR adresses all of your errors with code snippets?

[ccordoba12]

Thanks @andfoy! There are still some things not covered by this PR:

• Tab should not cycle among snippets but simply remove the snippet regions after reaching the last one and pressing Tab again.
• When you manually remove the text of a snippet, I think the snippet region of that snippet should be removed too.

[ccordoba12]

A couple more issues:

• Pressing Ctrl+Z or Crtl+X after editing a snippet doesn't restore the snippet positions. For example, in the screenshot below I removed the nc characters of func with backspace then press Ctrl+Z and got this result:

  

• If you manually move with the left/right arrow keys out of a snippet region, then all snippet regions should be removed. That's what VSCode does and I think it's a good approach.

[ccordoba12]

One more: if you enter the following code

from pandas import pd
pd.concat(objs)

and replace objs by as and other characters in quick sucession, then Spyder freezes (it's not always reproducible, but most of the time). After unfreeze it with a Ctrl+C in the terminal, I've got the following traceback related to snippets:

Traceback (most recent call last):
  File "/home/carlos/Projects/spyder/github-repo/spyder/plugins/editor/extensions/snippets.py", line 201, in _on_key_pressed
    self._process_text(text)
  File "/home/carlos/Projects/spyder/github-repo/spyder/plugins/editor/extensions/snippets.py", line 49, in wrapper
    return f(self, *args, **kwargs)
  File "/home/carlos/Projects/spyder/github-repo/spyder/plugins/editor/extensions/snippets.py", line 209, in _process_text
    self.insert_text(text, line, column)
  File "/home/carlos/Projects/spyder/github-repo/spyder/plugins/editor/extensions/snippets.py", line 335, in insert_text
    tokens = tokenize(text)
  File "/home/carlos/Projects/spyder/github-repo/spyder/utils/snippets/lexer.py", line 91, in tokenize
    if regex.match(temp_word) is not None:

[andfoy]

Pressing Ctrl+Z or Crtl+X after editing a snippet doesn't restore the snippet positions. For example, in the screenshot below I removed the nc characters of func with backspace then press Ctrl+Z and got this result:

I'm very aware of this case, this is due to the Ctrl+Z behaviour of the CodeEditor, as opposed to the snippets one, while the first deletes the last sequence of characters, the latter stores a tree copy for n and c keypresses. Thus, when the undo call is applied, we backtrack to the "n" tree, rather to delete the "n" and "c" trees.

Is there any way to get the length of the undo text?

[ccordoba12]

You'll have to look for it because I don't know, sorry.

[goanpeca]

@andfoy if I do the following

import json
json.dumps(123, 123)

# Entering snippet mode type 123 tab 123, then selecting all (while I still see the
# snippet squares) and delete everything I get

    self.insert_text(text, line, column)
  File "/Users/gpena-castellanos/Google Drive/develop/quansight/spyder/spyder/plugins/editor/extensions/snippets.py", line 339, in insert_text
    if node.name == 'EPSILON':
AttributeError: 'NoneType' object has no attribute 'name'

[andfoy]

@andfoy if I do the following

Does this happens with this PR?

[goanpeca]

Yes, it still happens qith this Pr

[andfoy]

@goanpeca Could you please and try again?

[goanpeca]

Sure! After lunch 🥗:-)

[goanpeca]

@goanpeca Could you please and try again?

The latest fixes the issue @andfoy

[pep8speaks]

Hello @andfoy! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file spyder/plugins/editor/extensions/snippets.py:

Line 156:80: E501 line too long (80 > 79 characters)
Line 180:80: E501 line too long (80 > 79 characters)

Comment last updated at 2019-09-28 18:09:56 UTC

[andfoy]

@ccordoba12 Does the last commit fixes all the undo behaviour?

[ccordoba12]

@andfoy, I'm still seeing #10256 (comment) with this PR.

[andfoy]

@ccordoba12 I cannot reproduce that one:

[ccordoba12]

@andfoy, test_code_snippets is hanging now.

[andfoy]

@ccordoba12 The azure test fail is unrelated to this one

[ccordoba12]

@andfoy, please skip test_code_snippets on Windows, that could make our test suite pass there (I don't have time right now to analyze what's the problem that that test seems to be introducing).

[ccordoba12]

Thanks a lot @andfoy!! Great work here!