POC for "rename" functionality

LSPs can offer a rename capability to rename a "symbol" across a workspace.
We're not there yet, but this is a starting point. In VS Code it can be used by
right clicking a symbol (currently variable or call to local function) and
selecting "Rename symbol". A dialog should pop up asking for a new name.

Official spec:
https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_rename

apps/language_server/lib/language_server/protocol.ex

@@ -181,6 +181,25 @@ defmodule ElixirLS.LanguageServer.Protocol do
     end
   end
 
+  defmacro rename_req(id, uri, line, character, new_name) do
+    quote do
+      request(unquote(id), "textDocument/rename", %{
+        "textDocument" => %{"uri" => unquote(uri)},
+        "position" => %{"line" => unquote(line), "character" => unquote(character)},
+        "newName" => unquote(new_name)
+      })
+    end
+  end
+
+  defmacro prepare_rename_req(id, uri, line, character) do
+    quote do
+      request(unquote(id), "textDocument/prepareRename", %{
+        "textDocument" => %{"uri" => unquote(uri)},
+        "position" => %{"line" => unquote(line), "character" => unquote(character)}
+      })
+    end
+  end
+
   defmacro execute_command_req(id, command, arguments) do
     quote do
       request(unquote(id), "workspace/executeCommand", %{

apps/language_server/lib/language_server/providers/rename.ex

@@ -0,0 +1,100 @@
+defmodule ElixirLS.LanguageServer.Providers.Rename do
+  @moduledoc """
+  Provides functionality to rename a symbol inside a workspace
+
+  https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_rename
+  """
+
+  alias ElixirLS.LanguageServer.SourceFile
+  #import ElixirLS.LanguageServer.Protocol
+
+  def rename(%SourceFile{} = source_file, start_uri, line, character, new_name) do
+    edits =
+      with %{context: {context, char_ident}} when context in [:local_or_var, :local_call] <-
+             Code.Fragment.surround_context(source_file.text, {line, character}),
+           %ElixirSense.Location{} = definition <-
+             ElixirSense.definition(source_file.text, line, character),
+           references <- ElixirSense.references(source_file.text, line, character) do
+
+
+        length_old = length(char_ident)
+
+        [
+          %{
+            uri: start_uri,
+            range:
+              adjust_range(
+                definition.line,
+                definition.column,
+                definition.line,
+                definition.column + length_old
+              )
+          }
+          | repack_references(references, start_uri)
+        ]
+      else
+        _ ->
+          []
+      end
+
+    changes =
+      edits
+      |> Enum.group_by(& &1.uri)
+      |> Enum.map(fn {uri, edits} ->
+        %{
+          "textDocument" => %{
+            "uri" => uri,
+            "version" => source_file.version + 1
+          },
+          "edits" =>
+            Enum.map(edits, fn edit ->
+              %{"range" => edit.range, "newText" => new_name}
+            end)
+        }
+      end)
+
+    {:ok, %{"documentChanges" => changes}}
+  end
+
+  def prepare(%SourceFile{} = source_file, _uri, line, character) do
+    result =
+      with %{
+             begin: {start_line, start_col},
+             end: {end_line, end_col},
+             context: {context, char_ident}
+           } when context in [:local_or_var, :local_call] <- Code.Fragment.surround_context(source_file.text, {line, character}) do
+        %{
+          range: adjust_range(start_line, start_col, end_line, end_col),
+          placeholder: to_string(char_ident)
+        }
+      else
+        _ ->
+          # Not a variable or local call, skipping for now
+          nil
+      end
+
+    {:ok, result}
+  end
+
+  defp repack_references(references, uri) do
+    for reference <- references do
+      %{
+        uri: uri,
+        range: %{
+          end: %{character: reference.range.end.column - 1, line: reference.range.end.line - 1},
+          start: %{
+            character: reference.range.start.column - 1,
+            line: reference.range.start.line - 1
+          }
+        }
+      }
+    end
+  end
+
+  defp adjust_range(start_line, start_character, end_line, end_character) do
+    %{
+      start: %{line: start_line - 1, character: start_character - 1},
+      end: %{line: end_line - 1, character: end_character - 1}
+    }
+  end
+end

apps/language_server/lib/language_server/server.ex

@@ -24,6 +24,7 @@ defmodule ElixirLS.LanguageServer.Server do
     Definition,
     Implementation,
     References,
+    Rename,
     Formatting,
     SignatureHelp,
     DocumentSymbols,
@@ -739,6 +740,26 @@ defmodule ElixirLS.LanguageServer.Server do
     {:async, fun, state}
   end
 
+  defp handle_request(rename_req(_id, uri, line, character, new_name), state = %__MODULE__{}) do
+    source_file = get_source_file(state, uri)
+
+    fun = fn ->
+      Rename.rename(source_file, uri, line + 1, character + 1, new_name)
+    end
+
+    {:async, fun, state}
+  end
+
+  defp handle_request(prepare_rename_req(_id, uri, line, character), state = %__MODULE__{}) do
+    source_file = get_source_file(state, uri)
+
+    fun = fn ->
+      Rename.prepare(source_file, uri, line + 1, character + 1)
+    end
+
+    {:async, fun, state}
+  end
+
   defp handle_request(execute_command_req(_id, command, args) = req, state = %__MODULE__{}) do
     {:async,
      fn ->
@@ -809,6 +830,7 @@ defmodule ElixirLS.LanguageServer.Server do
       "workspaceSymbolProvider" => true,
       "documentOnTypeFormattingProvider" => %{"firstTriggerCharacter" => "\n"},
       "codeLensProvider" => %{"resolveProvider" => false},
+      "renameProvider" => %{"prepareProvider" => true},
       "executeCommandProvider" => %{
         "commands" => ExecuteCommand.get_commands(server_instance_id)
       },

apps/language_server/test/providers/rename_test.exs

@@ -0,0 +1,213 @@
+defmodule ElixirLS.LanguageServer.Providers.RenameTest do
+  use ExUnit.Case, async: true
+
+  alias ElixirLS.LanguageServer.Providers.Rename
+  alias ElixirLS.LanguageServer.SourceFile
+  alias ElixirLS.LanguageServer.Test.FixtureHelpers
+  # mix cmd --app language_server mix test test/providers/rename_test.exs
+
+  @fake_uri "file:///World/Netherlands/Amsterdam/supercomputer/amazing.ex"
+
+  test "rename blank space" do
+    text = """
+    defmodule MyModule do
+      def hello() do
+        IO.inspect("hello world")
+      end
+    end
+    """
+
+    {line, char} = {2, 1}
+
+    assert {:ok, %{"documentChanges" => []}} =
+             Rename.rename(%SourceFile{text: text, version: 0}, @fake_uri, line, char, "test")
+  end
+
+  describe "renaming variable" do
+    test "a -> test" do
+      text = """
+      defmodule MyModule do
+        def add(a, b) do
+          a + b
+        end
+      end
+      """
+
+      # _a + b
+      {line, char} = {3, 5}
+
+      assert {:ok, %{"documentChanges" => changes}} =
+               Rename.rename(%SourceFile{text: text, version: 0}, @fake_uri, line, char, "test")
+
+      assert %{
+               "textDocument" => %{
+                 "uri" => @fake_uri,
+                 "version" => 1
+               },
+               "edits" => [
+                 %{
+                   "range" => %{end: %{character: 11, line: 1}, start: %{character: 10, line: 1}},
+                   "newText" => "test"
+                 },
+                 %{
+                   "range" => %{end: %{character: 5, line: 2}, start: %{character: 4, line: 2}},
+                   "newText" => "test"
+                 }
+               ]
+             } == List.first(changes)
+    end
+
+    test "nema -> name" do
+      text = """
+      defmodule MyModule do
+        def hello(nema) do
+          "Hello " <> nema
+        end
+      end
+      """
+
+      # "Hello " <> ne_ma
+      {line, char} = {3, 19}
+
+      assert {:ok, %{"documentChanges" => [changes]}} =
+               Rename.rename(
+                 %SourceFile{text: text, version: 0},
+                 @fake_uri,
+                 line,
+                 char,
+                 "name"
+               )
+
+      assert %{
+               "textDocument" => %{
+                 "uri" => @fake_uri,
+                 "version" => 1
+               },
+               "edits" => [
+                 %{
+                   "range" => %{end: %{character: 16, line: 1}, start: %{character: 12, line: 1}},
+                   "newText" => "name"
+                 },
+                 %{
+                   "range" => %{end: %{character: 20, line: 2}, start: %{character: 16, line: 2}},
+                   "newText" => "name"
+                 }
+               ]
+             } == changes
+    end
+  end
+
+  describe "renaming local function" do
+    test "create_message -> store_message" do
+      file_path = FixtureHelpers.get_path("rename_example.exs")
+      text = File.read!(file_path)
+      uri = SourceFile.path_to_uri(file_path)
+
+      # |> _create_message
+      {line, char} = {28, 8}
+
+      assert {:ok, %{"documentChanges" => [changes]}} =
+               Rename.rename(
+                 %SourceFile{text: text, version: 0},
+                 uri,
+                 line,
+                 char,
+                 "store_message"
+               )
+
+      assert %{
+               "textDocument" => %{
+                 "uri" => uri,
+                 "version" => 1
+               },
+               "edits" => [
+                 %{
+                   "newText" => "store_message",
+                   "range" => %{end: %{character: 21, line: 43}, start: %{character: 7, line: 43}}
+                 },
+                 %{
+                   "newText" => "store_message",
+                   "range" => %{end: %{character: 21, line: 27}, start: %{character: 7, line: 27}}
+                 }
+               ]
+             } == changes
+    end
+  end
+
+  describe "not yet (fully) supported/working renaming cases" do
+    test "rename started with cursor at function definition" do
+      file_path = FixtureHelpers.get_path("rename_example.exs")
+      text = File.read!(file_path)
+      uri = SourceFile.path_to_uri(file_path)
+
+      # defp _handle_error({:ok, message})
+      {line, char} = {4, 8}
+
+      assert {:ok, %{"documentChanges" => changes}} =
+               Rename.rename(
+                 %SourceFile{text: text, version: 0},
+                 uri,
+                 line,
+                 char,
+                 "handle_errors"
+               )
+
+      refute %{
+               "textDocument" => %{
+                 "uri" => uri,
+                 "version" => 1
+               },
+               "edits" => [
+                 %{
+                   "newText" => "handle_errors",
+                   "range" => %{end: %{character: 19, line: 37}, start: %{character: 7, line: 37}}
+                 },
+                 %{
+                   "newText" => "handle_errors",
+                   "range" => %{end: %{character: 19, line: 39}, start: %{character: 7, line: 39}}
+                 },
+                 %{
+                   "newText" => "handle_errors",
+                   "range" => %{end: %{character: 19, line: 28}, start: %{character: 7, line: 28}}
+                 }
+               ]
+             } == List.first(changes)
+    end
+
+    test "rename function with multiple heads" do
+      file_path = FixtureHelpers.get_path("rename_example.exs")
+      text = File.read!(file_path)
+      uri = SourceFile.path_to_uri(file_path)
+
+      # |> _handle_error
+      {line, char} = {29, 8}
+
+      assert {:ok, %{"documentChanges" => [changes]}} =
+               Rename.rename(
+                 %SourceFile{text: text, version: 0},
+                 uri,
+                 line,
+                 char,
+                 "handle_errors"
+               )
+
+      # missed second function head on line 40: handle_error({:error, changeset})
+      assert %{
+               "textDocument" => %{
+                 "uri" => uri,
+                 "version" => 1
+               },
+               "edits" => [
+                 %{
+                   "newText" => "handle_errors",
+                   "range" => %{end: %{character: 19, line: 37}, start: %{character: 7, line: 37}}
+                 },
+                 %{
+                   "newText" => "handle_errors",
+                   "range" => %{end: %{character: 19, line: 28}, start: %{character: 7, line: 28}}
+                 }
+               ]
+             } == changes
+    end
+  end
+end