Provide a way to let embedded language have its own completionTriggers

[octref]

Context: vuejs/vetur#705

Vue language server uses : to suggest Vue html properties, such as <div :foo="bar">. However, this can cause : to trigger completions in the <script> section, which is not what the user want.

The only way to achieve it today seems to be splitting the server into two servers, which seem to be a huge amount of work.

I don't know if it's possible to provide a way to let embedded language have its own completionTriggers, but one alternative I can think of is to allow server to say "provide no suggestion on client side" in LSP. Currently returning empty array of CompletionItem still trigger word-based completion.

[dbaeumer]

@octref I don't actually understand what you mean by provide no suggestion on client side. Can you make a more concrete example ?

[jrieken]

I don't know if it's possible to provide a way to let embedded language have its own completionTriggers, but

The concept of an embedded language doesn't exist in API-terms. It's always the "outer languages" that is in charge of decision making. So, it should register : as completion character but then it must decide if that occurrence of the character is valid. Even "simple" languages must do this, e.g the . isn't always a valid trigger character for TypeScript et al.

[octref]

@dbaeumer
Sorry I had an incomplete understanding of word based suggestions. I thought for each completion trigger, when nothing is being returned VS Code would fallback to word-based suggestions. Turned out it's only when completions are triggered by non-symbol characters.

@jrieken
OK. I'll use completion's position to find character to the left of cursor and determine if it's a valid completion trigger in its embedded context.