Implementations provider (#415)

* move to provider

* no need to feature check as formatter and references are available since elixir 1.7 and we require 1.8

* elixir_sense suggestions for erlang modules now properly include :

no need to patch

* elixir_sense definitions now return nil when not found

extract location  related code to a new module

* add implementations provider

* update elixir_sense

* do not format test/tmp fixtures

* move fixtures to common dir

* do not build filesystem URIs by string concat as it will break on Windows

* add tests

* fix invalid uris

* Revert "do not format test/tmp fixtures"

This reverts commit 5012101.

* Revert "fix invalid uris"

This reverts commit 38eeb67.

* run formatter

* increase timeout

* bump elixir_sense

* don't catch everyting

* bump elixir_sense

fix tests on elixir < 1.11

Author: lukaszsamson

apps/language_server/lib/language_server/protocol.ex

@@ -101,6 +101,15 @@ defmodule ElixirLS.LanguageServer.Protocol do
     end
   end
 
+  defmacro implementation_req(id, uri, line, character) do
+    quote do
+      request(unquote(id), "textDocument/implementation", %{
+        "textDocument" => %{"uri" => unquote(uri)},
+        "position" => %{"line" => unquote(line), "character" => unquote(character)}
+      })
+    end
+  end
+
   defmacro completion_req(id, uri, line, character) do
     quote do
       request(unquote(id), "textDocument/completion", %{

apps/language_server/lib/language_server/protocol/location.ex

@@ -6,4 +6,23 @@ defmodule ElixirLS.LanguageServer.Protocol.Location do
   """
   @derive JasonVendored.Encoder
   defstruct [:uri, :range]
+
+  alias ElixirLS.LanguageServer.SourceFile
+  alias ElixirLS.LanguageServer.Protocol
+
+  def new(%ElixirSense.Location{file: file, line: line, column: column}, uri) do
+    uri =
+      case file do
+        nil -> uri
+        _ -> SourceFile.path_to_uri(file)
+      end
+
+    %Protocol.Location{
+      uri: uri,
+      range: %{
+        "start" => %{"line" => line - 1, "character" => column - 1},
+        "end" => %{"line" => line - 1, "character" => column - 1}
+      }
+    }
+  end
 end

apps/language_server/lib/language_server/providers/completion.ex

@@ -236,37 +236,26 @@ defmodule ElixirLS.LanguageServer.Providers.Completion do
 
   defp from_completion_item(
          %{type: :module, name: name, summary: summary, subtype: subtype, metadata: metadata},
-         %{
-           def_before: nil,
-           prefix: prefix
-         },
+         %{def_before: nil},
          _options
        ) do
-    capitalized? = String.first(name) == String.upcase(String.first(name))
-
-    if String.ends_with?(prefix, ":") and capitalized? do
-      nil
-    else
-      label = if capitalized?, do: name, else: ":" <> name
-
-      detail =
-        if subtype do
-          Atom.to_string(subtype)
-        else
-          "module"
-        end
+    detail =
+      if subtype do
+        Atom.to_string(subtype)
+      else
+        "module"
+      end
 
-      %__MODULE__{
-        label: label,
-        kind: :module,
-        detail: detail,
-        documentation: summary,
-        insert_text: name,
-        filter_text: name,
-        priority: 14,
-        tags: metadata_to_tags(metadata)
-      }
-    end
+    %__MODULE__{
+      label: name,
+      kind: :module,
+      detail: detail,
+      documentation: summary,
+      insert_text: name,
+      filter_text: name,
+      priority: 14,
+      tags: metadata_to_tags(metadata)
+    }
   end
 
   defp from_completion_item(

apps/language_server/lib/language_server/providers/definition.ex

@@ -3,32 +3,18 @@ defmodule ElixirLS.LanguageServer.Providers.Definition do
   Go-to-definition provider utilizing Elixir Sense
   """
 
-  alias ElixirLS.LanguageServer.SourceFile
   alias ElixirLS.LanguageServer.Protocol
 
   def definition(uri, text, line, character) do
-    case ElixirSense.definition(text, line + 1, character + 1) do
-      %ElixirSense.Location{found: false} ->
-        {:ok, []}
+    result =
+      case ElixirSense.definition(text, line + 1, character + 1) do
+        nil ->
+          nil
 
-      %ElixirSense.Location{file: file, line: line, column: column} ->
-        line = line || 0
-        column = column || 0
+        %ElixirSense.Location{} = location ->
+          Protocol.Location.new(location, uri)
+      end
 
-        uri =
-          case file do
-            nil -> uri
-            _ -> SourceFile.path_to_uri(file)
-          end
-
-        {:ok,
-         %Protocol.Location{
-           uri: uri,
-           range: %{
-             "start" => %{"line" => line - 1, "character" => column - 1},
-             "end" => %{"line" => line - 1, "character" => column - 1}
-           }
-         }}
-    end
+    {:ok, result}
   end
 end

apps/language_server/lib/language_server/providers/formatting.ex

@@ -2,10 +2,6 @@ defmodule ElixirLS.LanguageServer.Providers.Formatting do
   import ElixirLS.LanguageServer.Protocol, only: [range: 4]
   alias ElixirLS.LanguageServer.SourceFile
 
-  def supported? do
-    function_exported?(Code, :format_string!, 2)
-  end
-
   def format(%SourceFile{} = source_file, uri, project_dir) do
     if can_format?(uri, project_dir) do
       case SourceFile.formatter_opts(uri) do

apps/language_server/lib/language_server/providers/implementation.ex

@@ -0,0 +1,14 @@
+defmodule ElixirLS.LanguageServer.Providers.Implementation do
+  @moduledoc """
+  Go-to-implementation provider utilizing Elixir Sense
+  """
+
+  alias ElixirLS.LanguageServer.Protocol
+
+  def implementation(uri, text, line, character) do
+    locations = ElixirSense.implementations(text, line + 1, character + 1)
+    results = for location <- locations, do: Protocol.Location.new(location, uri)
+
+    {:ok, results}
+  end
+end

apps/language_server/lib/language_server/providers/references.ex

@@ -24,10 +24,6 @@ defmodule ElixirLS.LanguageServer.Providers.References do
     end)
   end
 
-  def supported? do
-    Mix.Tasks.Xref.__info__(:functions) |> Enum.member?({:calls, 0})
-  end
-
   defp build_reference(ref, current_file_uri) do
     %{
       range: %{

apps/language_server/lib/language_server/providers/signature_help.ex

@@ -1,6 +1,8 @@
 defmodule ElixirLS.LanguageServer.Providers.SignatureHelp do
   alias ElixirLS.LanguageServer.SourceFile
 
+  def trigger_characters(), do: ["("]
+
   def signature(%SourceFile{} = source_file, line, character) do
     response =
       case ElixirSense.signature(source_file.text, line + 1, character + 1) do

apps/language_server/lib/language_server/server.ex

@@ -22,6 +22,7 @@ defmodule ElixirLS.LanguageServer.Server do
     Completion,
     Hover,
     Definition,
+    Implementation,
     References,
     Formatting,
     SignatureHelp,
@@ -475,10 +476,6 @@ defmodule ElixirLS.LanguageServer.Server do
     e in InvalidParamError ->
       JsonRpc.respond_with_error(id, :invalid_params, e.message)
       state
-
-    other ->
-      JsonRpc.respond_with_error(id, :internal_error, other.message)
-      state
   end
 
   defp handle_request_packet(id, _packet, state) do
@@ -546,6 +543,14 @@ defmodule ElixirLS.LanguageServer.Server do
     {:async, fun, state}
   end
 
+  defp handle_request(implementation_req(_id, uri, line, character), state) do
+    fun = fn ->
+      Implementation.implementation(uri, state.source_files[uri].text, line, character)
+    end
+
+    {:async, fun, state}
+  end
+
   defp handle_request(references_req(_id, uri, line, character, include_declaration), state) do
     source_file = get_source_file(state, uri)
 
@@ -731,9 +736,6 @@ defmodule ElixirLS.LanguageServer.Server do
         rescue
           e in InvalidParamError ->
             {:error, :invalid_params, e.message}
-
-          other ->
-            {:error, :internal_error, other.message}
         end
 
       GenServer.call(parent, {:request_finished, id, result}, :infinity)
@@ -751,9 +753,10 @@ defmodule ElixirLS.LanguageServer.Server do
       "hoverProvider" => true,
       "completionProvider" => %{"triggerCharacters" => Completion.trigger_characters()},
       "definitionProvider" => true,
-      "referencesProvider" => References.supported?(),
-      "documentFormattingProvider" => Formatting.supported?(),
-      "signatureHelpProvider" => %{"triggerCharacters" => ["("]},
+      "implementationProvider" => true,
+      "referencesProvider" => true,
+      "documentFormattingProvider" => true,
+      "signatureHelpProvider" => %{"triggerCharacters" => SignatureHelp.trigger_characters()},
       "documentSymbolProvider" => true,
       "workspaceSymbolProvider" => true,
       "documentOnTypeFormattingProvider" => %{"firstTriggerCharacter" => "\n"},

apps/language_server/test/providers/definition_test.exs

@@ -4,14 +4,15 @@ defmodule ElixirLS.LanguageServer.Providers.DefinitionTest do
   alias ElixirLS.LanguageServer.Providers.Definition
   alias ElixirLS.LanguageServer.Protocol.Location
   alias ElixirLS.LanguageServer.SourceFile
+  alias ElixirLS.LanguageServer.Test.FixtureHelpers
   require ElixirLS.Test.TextLoc
 
   test "find definition" do
-    file_path = Path.join(__DIR__, "../support/references_a.ex") |> Path.expand()
+    file_path = FixtureHelpers.get_path("references_a.ex")
     text = File.read!(file_path)
     uri = SourceFile.path_to_uri(file_path)
 
-    b_file_path = Path.join(__DIR__, "../support/references_b.ex") |> Path.expand()
+    b_file_path = FixtureHelpers.get_path("references_b.ex")
     b_uri = SourceFile.path_to_uri(b_file_path)
 
     {line, char} = {2, 30}