Support EvaluatableExpressions

[tsmaeder]

Feature Description:

Implement support for plugins providing evalutable epressions. see https://code.visualstudio.com/api/references/vscode-api#EvaluatableExpression

Currently, the the debugger scans the current line to guess what expressions to evaluate and show in the hover widget. Instead, the debuggers should forward that work to plugins. It may be necessary to keep the current logic as a fallback when no expressions are provided for a particular location.

[ndoschek]

I will pick up this issue

[alvsan09]

Hi @ndoschek,
I am wondering what the status of your current commit is?
Are you planning to continue with it?

[ndoschek]

Hi @alvsan09!
Sorry I was a bit delayed, but I'm planning to complete it this month.

[ndoschek]

Awaits uplift of monaco to add the necessary types in the monaco.languages namespace.
Please see PR: theia-ide/vscode#1

@tsmaeder @colin-grant-work
I had a look and noticed the missing types in the monaco.languages namespace. After some investigation I found the branch uplift-monaco-2022-06 on theia's fork of vscode.
Is it sufficient to add those types there or would you suggest to add them to vscode directly? TIA!

[colin-grant-work]

@ndoschek, in general, we avoid modifying the code of VSCode directly, so I would probably avoid the change in theia-ide/vscode#1. I'm also a little bit confused by the code in that PR. It appears that it adds declarations to monaco.d.ts for the functions registerEvaluatableExpressionProvider and registerInlineValuesProvider but doesn't modify the source code to actually provide those functions in the API object? To actually support new languages API, changes would be required in the createMonacoLanguagesAPI function in src/vs/editor/standalone/browser/standaloneLanguages.ts.

I have opened a PR to uplift our Monaco dependency to VSCode 1.67.2, and I believe that the EvaluatableExpression and EvaluatableExpressionProvider types are available there - not from the API, but via imports from the source - and it appears that the registration should be possible using the ILanguageFeaturesService, which we can access using Monaco's InstantiationService:

theia/packages/monaco/src/browser/monaco-outline-contribution.ts

Lines 46 to 48 in b63943c

	StandaloneServices.get(ILanguageFeaturesService).documentSymbolProvider.onDidChange(
	debounce(() => this.updateOutline())
	);

theia/packages/monaco/src/browser/monaco-outline-contribution.ts

Line 133 in b63943c

const providers = StandaloneServices.get(ILanguageFeaturesService).documentSymbolProvider.all(model);

Given that, I would wait until the uplift / rebase your work on the uplift branch here in the Theia project and work from there, rather than modifying the VSCode source.

[ndoschek]

Hi @colin-grant-work!
Thanks for your input! I have a WIP branch and I will try your suggested way of using the ILanguageFeaturesService in the meantime and I will abandon my PR and wait for the uplift then. Thanks again!