Determining valid symbols for computeContentAssist

[knpwrs]

I have a working lexer and parser for the liquid templating language that I built using Chevrotain, and I am able to get completion suggestions using computeContentAssist, which is really cool! However, looking at this example (

chevrotain/examples/parser/content_assist/content_assist_complex.js

Line 137 in 4272462

export function getContentAssistSuggestions(text, symbolTable) {

) it seems like there isn't a built-in way to get contextual symbol information. Consider:

{% for i in (1..5) %}
  {% if i == 4 %}
    {% continue %}
  {% else %}
    {{ |

With the cursor at |, I want to suggest the variable i. I've been attempting to find a way to find variables defined in scope based on the CST or any other data I have available, but I'm at a loss. I've even tried setting global state using this.ACTION but this.ACTION doesn't appear to run while calling computeContentAssist (and thinking about it I understand why this is, multiple paths are traversed to find suggestions and so the global state would not be reliable).

Is there any way to get a partial cst of any sort or any contextual structure I can traverse to determine what variables are defined in scope?

The rule stack for the first suggestion from above is:

root
doc
controlFor
doc
controlIf
doc
object
expression

A great start would be the ability to look at the structure of that controlFor, since a variable can be defined there, but it would also be great to be able to look at the structure of sibling assign rules.

[msujew]

Hey @knpwrs,

generally, the existing content assist functionality in Chevrotain is fairly barebones. The recommended solution is actually to build a specific parser for content assist, see a pretty extensive answer here. Content assist in general is a pretty complicated topic and I've spent weeks working on the implementation in Langium (based on Chevrotain) to create something that works most of the time.