elixir-ls now recognizes umbrella projects

Previously, elixir-ls would treat each sub-project within an umbrella as
standalone, which isn't desirable from a language server perspective.

Added ale#handlers#elixir#FindMixUmbrellaRoot, which locates the current
project's root and then continues searching upwards for a potential
umbrella project root. This literally looks just two levels up to keep
things simple while keeping in line with Elixir project conventions.

Use this new function to determine elixir-ls's LSP project root.

1 files changed, 18 insertions, 3 deletions

diff --git a/autoload/ale/handlers/elixir.vim b/autoload/ale/handlers/elixir.vim
index 91b75aac..2fddf8e7 100644
--- a/autoload/ale/handlers/elixir.vim
+++ b/autoload/ale/handlers/elixir.vim
@@ -1,13 +1,28 @@
 " Author: Matteo Centenaro (bugant) - https://github.com/bugant
-"
-" Description: find the root directory for an elixir project that uses mix
+" Author: Jon Parise <jon@indelible.org>
+" Description: Functions for working with Elixir projects
 
+" Find the root directory for an elixir project that uses mix.
 function! ale#handlers#elixir#FindMixProjectRoot(buffer) abort
     let l:mix_file = ale#path#FindNearestFile(a:buffer, 'mix.exs')
 
     if !empty(l:mix_file)
-      return fnamemodify(l:mix_file, ':p:h')
+        return fnamemodify(l:mix_file, ':p:h')
     endif
 
     return '.'
 endfunction
+
+" Similar to ale#handlers#elixir#FindMixProjectRoot but also continue the
+" search upward for a potential umbrella project root. If an umbrella root
+" does not exist, the initial project root will be returned.
+function! ale#handlers#elixir#FindMixUmbrellaRoot(buffer) abort
+    let l:app_root = ale#handlers#elixir#FindMixProjectRoot(a:buffer)
+    let l:umbrella_root = fnamemodify(l:app_root, ':h:h')
+
+    if filereadable(l:umbrella_root . '/mix.exs')
+        return l:umbrella_root
+    endif
+
+    return l:app_root
+endfunction