Support auto-closing quotes in Python raw string literals, etc

[Syeberman]

Python uses a "string prefix" to denote bytes literals (b''), raw strings (r''), and formatted string literals (f''). This change makes it so that when one types r' in VS Code, the string will be auto-closed as r'' (as an example).

Python also supports multiple string prefixes for a single literal. I've tested that typing fr' will auto-close to fr'', and so forth.

[msftclas]

All CLA requirements met.

[javadev]

It may be unit tested.

[aeschli]

Isn't it enough to just have ' and " as an auto pair character? The only difference I'm aware of is that undo will only remove the quote, instead of the letter before, but IMO that's better anyway.

[Syeberman]

The original auto-close setting did not auto-close r', etc. Presumably, it's coded to only trigger after a whitespace (or non-word boundary), but I didn't look at the code.

Oddly, this doesn't explain why the above configuration auto-closes fr', etc. If the open pattern must be preceded by whitespace, then that shouldn't work. Perhaps it's coded differently if the pattern starts with an alphanumeric character?

[aeschli]

Yes, there's a condition to not autoclose ' after a word.
@alexandrudima Do you want to reconsider that, or is the PR ok?

[aeschli]

Sorry, this slipped. @alexandrudima Waiting for your opinion.

[alexdima]

The following added rules do nothing:

		{ "open": "r\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "R\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "u\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "U\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "f\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "F\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "b\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "B\"", "close": "\"", "notIn": ["string", "comment"] },
		{ "open": "r'", "close": "'", "notIn": ["string", "comment"] },
		{ "open": "R'", "close": "'", "notIn": ["string", "comment"] },
		{ "open": "u'", "close": "'", "notIn": ["string", "comment"] },
		{ "open": "U'", "close": "'", "notIn": ["string", "comment"] },
		{ "open": "f'", "close": "'", "notIn": ["string", "comment"] },
		{ "open": "F'", "close": "'", "notIn": ["string", "comment"] },
		{ "open": "b'", "close": "'", "notIn": ["string", "comment"] },
		{ "open": "B'", "close": "'", "notIn": ["string", "comment"] }

Out of the added rules, this is the only one that might do something:

		{ "open": "'", "close": "'", "notIn": ["string", "comment"] },

Closing Pairs are implemented to be working on single characters. Basically, the code evaluates if someone typed the character in the open part of a closing pair and does not consider any characters before the auto closing open character.

[Syeberman]

@alexandrudima I tested this configuration myself when I submitted this PR. Without my changes, when you type r', it does not auto-close to r''. With my changes, it properly auto-closes raw, unicode, f-strings, and bytes.

[alexdima]

Yes, that's what I'm saying too. The only line that makes this work from this PR is:

{ "open": "'", "close": "'", "notIn": ["string", "comment"] },

This defines that ' - ' forms an auto-closing pair.

The other 16 lines serve no purpose.

[aeschli]

@alexandrudima
{ "open": "'", "close": "'", "notIn": ["string", "comment"] }, is already part of the autoClosingPair.
It doesn't work after r' due to this.
Adding { "open": "r'", "close": "'", "notIn": ["string", "comment"] }, fixes the problem

[alexdima]

@Syeberman @aeschli I agree the change makes this feature work. I was quite stumped at first, since I am pretty sure how auto-closing characters should work and how they're implemented.

As I thought, the execution does not enter the auto closing open character code (since that is implemented to only work on single characters), but it enters BracketElectricCharacterSupport._onElectricAutoClose and these newly added auto-closing pairs somehow make their way to _complexAutoClosePairs.

@aeschli Since this is something you've authored in ebc3074 , I cannot be of further assistance.

Perhaps now would be a good time to document somewhere this behaviour!

[aeschli]

Talked to @alexandrudima again and we are fine with the PR. Not autoclosing ' and " after a letter is the expected behaviour most languages, so the PR makes sense to add additional rules fo the cases where this makes sense.

Thanks @Syeberman!

[redeemefy]

I still have the issue on Version 1.21.1 (1.21.1) and running OSX Sierra.

[aeschli]

@diazgilberto Please file a new issue with a code sample that shows the problem. Also try to run without extensions to see whether an external extension causes this.