refactor: remove SourceMap dependency from dep-graph

[dsherret]

There isn't any need for analyze_dependencies to use a SourceMap. Instead it can stay working with span/byte pos units so it's the same as the AST (that way, we don't mix units).

Additionally, it doesn't need to be limited to SingleThreadedComments and can instead take anything that implements the Comments trait.

What I'm trying to do is hold onto swc ASTs in Deno's language server, but I need everything to be Send in order to do that. Source map doesn't allow that, so it's up on the chopping block right now. Next will be SourceFile and SingleThreadedComments.

[kdy1]

Btw, Lrc<SourceMap> implements Send + Sync if you enable concurrent feature of swc_common.

[dsherret]

Btw, Lrc implements Send + Sync if you enable concurrent feature of swc_common.

Interesting. I feel like I knew that, but forgot and that's good to know! I don't want to turn on that feature because it would be a global change, would most likely be slower in our case, and introduces the possibility of a new class of bugs. I think I will be able to manage by only holding onto things like SourceFile and SourceMaps structs when we need them for things like transpiling and bundling or perhaps creating those after the fact again when needed. The rest of it should ideally work via only holding onto the AST, source file text, and comments (I will take them out of the SingleThreadedComments).

[kdy1]

I see. I'm okay with current changes, but I'm not sure if you want me to merge it.

[dsherret]

@kdy1 yeah, not yet. I want to look into fixing this possible race condition. I'm just looking into your comments.

[kdy1]

Is this PR ready? If not, please ping me when you are done :)

[dsherret]

Hey @kdy1, yeah, it is now. I’m just not sure about the changes to the comments trait and what would be best there.