Code fragment APIs

[josevalim]

For example, I would like something that would tell me

|> Foo.

"Yep, this is definitely in a pipe, and also this is the beginning of a call to a function in the Foo module"

Right now, I don't get that ability with anything I see in Code.Fragment.

for example:

Code.Fragment.container_cursor_to_quoted("|> Foo.")
{:ok, {:__cursor__, [line: 1], []}

and

Code.Fragment.cursor_context("|> Foo.")
{:dot, {:alias, 'Foo'}, []}

More helpful, but has no idea that I'm in a pipeline. We would like to know if we're in a pipeline because when we complete the arguments to functions, we remove the first one. We have similar needs for function captures as well, as we offer completions for &something/1 and &something(args).

Originally posted by @scohen in #12645 (comment)

[josevalim]

@scohen I moved it here to avoid side-tracking the other issue (I will delete the comments from there).

[josevalim]

Operator support to container_quoted was only added on v1.15 as per your request. But remember you need to give it full code:

iex(1)> Code.Fragment.container_cursor_to_quoted("Bar |> Foo.")
{:ok,
 {:|>, [line: 1],
  [{:__aliases__, [line: 1], [:Bar]}, {:__cursor__, [line: 1], []}]}}

For aliases, require, and import, we also discussed this in another issue:

#12566 (comment)

IEx handles both the alias and the struct cases, so its source code can be checked as an example.

There was also a discussion here: #12673

I will close this but feel free to drop additional comments (and I will reopen if we find something that needs to be supported).