Show breadcrumbs navigation when going to definition

[nounder]

Is your feature request related to a problem? Please describe.

When I Go to Definition of a symbol from a deno.land (or any other HTTP source), an editor opens with a file where that symbol is defined. However, the editor does not have breadcrumb navigation (just below tabs) that allows to see file hierarchy in which this file resides. This makes it hard to explore new packages without leaving programming environment.

Describe the solution you'd like

A breadcrumb navigation should be accessible in editor visiting remote module. Because there are many Deno packages that have high quality code, it is often enough to go through source code to understand it. Currently one has to use external tools which breaks the flow for a programmer.

[bartlomieju]

I took at stab at that and it appears the problem is that the remote dependencies are marked as "read-only" files which makes them not available to display breadcrumbs. I need to dig more to figure out if this is something we can change or now.

[bartlomieju]

The other problem might be that we don't register a "file provider" for http: and https: URL, but I'm still trying to figure out if we should.

[bartlomieju]

I did more digging and clicking on a http: or https: URL is actually causing to open a "virtual document". Virtual documents are "readonly" documents (as can be seen by trying to enter something in the opened document).

I believe this is a limitation of VSCode in that it doesn't show breadcrumbs for this virtual documents. @dsherret suggested that we should allow to edit documents in the global cache, so I'm afraid this might be a "wontfix".

[nounder]

One more possibility is using deno: URL with Deno-specific file provider. When user clicks import, the URL is rewritten to be handled by extension itself without overriding default behaviour.

File System API seems to provide fs-like abstraction for custom handles.

[dsherret]

It's infeasible to do this for the global cache because we don't have a reverse mapping of file path to remote url. The upcoming deno_modules directory feature will support this though so this issue will be closed by denoland/deno#20030