Automatic insertion of parens doesn't interact nicely with completions, results in duplicated characters

[DanTup]

• VSCode Version: 1.11.2
• OS Version: Windows 10

Assume the following code (cursor is where the | is):

foo() {
}


main() {
  fo|
}

Completion is returning foo(). If the user continues to type o( then the o and ( are "subtracted" from the completion client-side by Code (it doesn't send another request to the completion provider). This works great; however since typing the ( auto-inserts a ) if the user then uses the completion, they will end up with:

main() {
  foo()) // <-- two closing parens
}

There's an animation showing a slightly different version or this at Dart-Code/Dart-Code#285

I can't see how the completion provider can fix this, since Code has taken over completion at this point (it's filtering and reducing the completion text client-side). I think the best thing would be for Code to subtract any auto-inserted characters from the end of the completion text in the same way it's removing the typed characters from the start.

Eg, when the user types the (:

1. Filter the completion list by the (
2. Remove the ( from the completion text to be inserted, and adjust the range accordingly
3. Because a character was auto-inserted after the cursor, subtract that character from the end of the insertion text (and adjust the range) if it's the same character

I think 1 & 2 already happen, I think 3 would make sense to fix this.

[jrieken]

@alexandrudima Is there a way I can halt electric brackets for a moment?

[alexdima]

@jrieken I'm not 100% sure what you mean.

The code for handling typing is at typeWithInterceptors -- https://github.com/Microsoft/vscode/blob/master/src/vs/editor/common/controller/cursorTypeOperations.ts#L547

The cursor goes into that if the source of the type command is keyboard.

Would you want in the onWillType to cancel the editor's processing of type ?

[alexdima]

ping @jrieken What do you want in terms of editor API here ?

[jdneo]

There is another issue about the same thing: redhat-developer/vscode-java#503.

Since VS Code has taken over completion at this point, there is no chance for language server to handle with such case. VS Code should correct the bracket according to the current content and the snippet given by the language server.

[jrieken]

This is related to #10266 but the automatic brackets force you into this situation...