feat(commands): from-pipe

Author: mhanberg

lib/next_ls.ex

@@ -142,7 +142,8 @@ defmodule NextLS do
          document_formatting_provider: true,
          execute_command_provider: %GenLSP.Structures.ExecuteCommandOptions{
            commands: [
-              "to-pipe"
+              "to-pipe",
+              "from-pipe"
             ]
          },
          hover_provider: true,
@@ -618,6 +619,19 @@ defmodule NextLS do
       ) do
     reply =
       case command do
+        "from-pipe" ->
+          [arguments] = params.arguments
+
+          uri = arguments["uri"]
+          position = arguments["position"]
+          text = lsp.assigns.documents[uri]
+
+          NextLS.Commands.FromPipe.new(%{
+            uri: uri,
+            text: text,
+            position: position
+          })
+
         "to-pipe" ->
           [arguments] = params.arguments
 

lib/next_ls/commands/from_pipe.ex

@@ -0,0 +1,104 @@
+defmodule NextLS.Commands.FromPipe do
+  @moduledoc false
+  alias GenLSP.Enumerations.ErrorCodes
+  alias GenLSP.Structures.Position
+  alias GenLSP.Structures.Range
+  alias GenLSP.Structures.TextEdit
+  alias GenLSP.Structures.WorkspaceEdit
+  alias NextLS.EditHelpers
+
+  defp opts do
+    Schematic.map(%{
+      position: Position.schematic(),
+      uri: Schematic.str(),
+      text: Schematic.list(Schematic.str())
+    })
+  end
+
+  def new(opts) do
+    with {:ok, %{text: text, uri: uri, position: position}} <- Schematic.unify(opts(), Map.new(opts)),
+         {:ok, %TextEdit{} = edit} <- from_pipe_edit(text, position) do
+      %WorkspaceEdit{
+        changes: %{
+          uri => [edit]
+        }
+      }
+    else
+      {:error, message} ->
+        %GenLSP.ErrorResponse{code: ErrorCodes.parse_error(), message: inspect(message)}
+
+      {:error, _ast, messages} ->
+        error =
+          Enum.map_join(messages, "\n", fn {ctx, message} ->
+            message <> " on line: #{ctx[:line]}, column: #{ctx[:column]}"
+          end)
+
+        %GenLSP.ErrorResponse{code: ErrorCodes.parse_error(), message: error}
+    end
+  end
+
+  defp find_pipe_lines(ast, position) do
+    pipes =
+      ast
+      |> Macro.postwalker()
+      |> Enum.filter(fn
+        {:|>, context, _} -> (context[:line] || 0) - 1 == position.line
+        _ -> false
+      end)
+
+    if pipes != [] do
+      pipe_to_inline = Enum.min_by(pipes, fn {_, context, _} -> abs(position.character - context[:column]) end)
+      {:|>, _ctx, [{_, lhs, _}, {_, rhs, _}]} = pipe_to_inline
+      open = lhs
+      closing = rhs[:closing] || rhs[:end_of_expression] || rhs[:end]
+
+      range = %Range{
+        start: %Position{line: open[:line] - 1, character: open[:column] - 1},
+        end: %Position{line: closing[:line] - 1, character: closing[:column]}
+      }
+
+      {:ok, pipe_to_inline, range}
+    else
+      {:error, "could not find a pipe to inline"}
+    end
+  end
+
+  defp from_pipe_edit(text, position) do
+    with {:ok, ast} <- code_to_ast(text),
+         {:ok, ast_to_edit, range} <- find_pipe_lines(ast, position),
+         {:ok, indent} = EditHelpers.get_indent(text, position.line),
+         edit <- get_edit(ast_to_edit, indent) do
+      {:ok, %TextEdit{new_text: edit, range: range}}
+    else
+      error -> error
+    end
+  end
+
+  defp code_to_ast(lines) do
+    lines
+    |> Enum.join("\n")
+    |> Spitfire.parse()
+  end
+
+  defp get_edit(ast, indent) do
+    ast
+    |> inline_pipe()
+    |> Macro.to_string()
+    |> EditHelpers.add_indent_to_edit(indent)
+  end
+
+  defp inline_pipe(ast) do
+    {result, _} =
+      Macro.postwalk(ast, _changed = false, fn
+        {:|>, _context, [left_arg, right_arg]}, false ->
+          {call, context, args} = right_arg
+          ast = {call, context, [left_arg | args]}
+          {ast, true}
+
+        ast, acc ->
+          {ast, acc}
+      end)
+
+    result
+  end
+end

test/next_ls/commands/from_pipe_test.exs

@@ -0,0 +1,203 @@
+defmodule NextLS.Commands.FromPipeTest do
+  use ExUnit.Case, async: true
+
+  alias GenLSP.Structures.TextEdit
+  alias GenLSP.Structures.WorkspaceEdit
+  alias NextLS.Commands.FromPipe
+
+  @parse_error_code -32_700
+
+  describe "from-pipe" do
+    test "works on one liners" do
+      uri = "my_app.ex"
+
+      text =
+        String.split(
+          """
+          defmodule MyApp do
+            def to_list(map) do
+              map |> Enum.to_list()
+            end
+          end
+          """,
+          "\n"
+        )
+
+      position = %{"line" => 2, "character" => 9}
+      expected_line = Enum.at(text, 2)
+
+      assert %WorkspaceEdit{changes: %{^uri => [edit = %TextEdit{range: range}]}} =
+               FromPipe.new(%{uri: uri, text: text, position: position})
+
+      assert edit.new_text == "Enum.to_list(map)"
+      assert range.start.line == 2
+      assert range.start.character == 4
+      assert range.end.line == 2
+      assert range.end.character == String.length(expected_line)
+    end
+
+    test "works on one liners with multiple pipes" do
+      uri = "my_app.ex"
+
+      text =
+        String.split(
+          """
+          defmodule MyApp do
+            def to_list(map) do
+              map |> Enum.to_list() |> Map.new()
+            end
+          end
+          """,
+          "\n"
+        )
+
+      position = %{"line" => 2, "character" => 9}
+
+      assert %WorkspaceEdit{changes: %{^uri => [edit = %TextEdit{range: range}]}} =
+               FromPipe.new(%{uri: uri, text: text, position: position})
+
+      assert edit.new_text == "Enum.to_list(map)"
+      assert range.start.line == 2
+      assert range.start.character == 4
+      assert range.end.line == 2
+      assert range.end.character == 25
+    end
+
+    test "works on separate lines when the cursor is on the pipe" do
+      # When the cursor is on the pipe
+      # We should get the line before it to build the ast
+      uri = "my_app.ex"
+
+      text =
+        String.split(
+          """
+          defmodule MyApp do
+            def to_list(map) do
+              map
+              |> Enum.to_list()
+              |> Map.new()
+            end
+          end
+          """,
+          "\n"
+        )
+
+      position = %{"line" => 3, "character" => 5}
+      expected_line = Enum.at(text, 3)
+
+      assert %WorkspaceEdit{changes: %{^uri => [edit = %TextEdit{range: range}]}} =
+               FromPipe.new(%{uri: uri, text: text, position: position})
+
+      assert edit.new_text == "Enum.to_list(map)"
+      assert range.start.line == 2
+      assert range.start.character == 4
+      assert range.end.line == 3
+      assert range.end.character == String.length(expected_line)
+    end
+
+    test "works on separate lines when the cursor is on the var" do
+      # When the cursor is on the var
+      # we should get the next line to build the ast
+      uri = "my_app.ex"
+
+      text =
+        String.split(
+          """
+          defmodule MyApp do
+            def to_list(map) do
+              map
+              |> Enum.to_list()
+              |> Map.new()
+            end
+          end
+          """,
+          "\n"
+        )
+
+      position = %{"line" => 3, "character" => 5}
+      expected_line = Enum.at(text, 3)
+
+      assert %WorkspaceEdit{changes: %{^uri => [edit = %TextEdit{range: range}]}} =
+               FromPipe.new(%{uri: uri, text: text, position: position})
+
+      assert edit.new_text == "Enum.to_list(map)"
+      assert range.start.line == 2
+      assert range.start.character == 4
+      assert range.end.line == 3
+      assert range.end.character == String.length(expected_line)
+    end
+
+    test "we get an error reply if the ast is bad" do
+      uri = "my_app.ex"
+
+      text =
+        String.split(
+          """
+          defmodule MyApp do
+            def to_list(map) do
+              |> map
+              |> Enum.to_list()
+            end
+          end
+          """,
+          "\n"
+        )
+
+      position = %{"line" => 3, "character" => 5}
+
+      assert %GenLSP.ErrorResponse{code: @parse_error_code, message: message} =
+               FromPipe.new(%{uri: uri, text: text, position: position})
+
+      assert message =~ "unknown token: end on line: 6, column: 1"
+    end
+
+    test "we handle schematic errors" do
+      assert %GenLSP.ErrorResponse{code: @parse_error_code, message: message} = FromPipe.new(%{bad_arg: :is_very_bad})
+
+      assert message =~ "position: \"expected a map\""
+    end
+
+    test "handles a pipe expression on multiple lines" do
+      uri = "my_app.ex"
+
+      text =
+        String.split(
+          """
+          defmodule MyApp do
+            def all_odd?(map) do
+              map
+              |> Enum.all?(fn {x, y} ->
+                Integer.is_odd(y)
+              end)
+            end
+          end
+          """,
+          "\n"
+        )
+
+      expected_edit =
+        String.trim_trailing("""
+        Enum.all?(
+              map,
+              fn {x, y} ->
+                Integer.is_odd(y)
+              end
+            )
+        """)
+
+      # When the position is on `map` and on the cursor
+      position = %{"line" => 3, "character" => 10}
+
+      expected_line = Enum.at(text, 5)
+
+      assert %WorkspaceEdit{changes: %{^uri => [edit = %TextEdit{range: range}]}} =
+               FromPipe.new(%{uri: uri, text: text, position: position})
+
+      assert edit.new_text == expected_edit
+      assert range.start.line == 2
+      assert range.start.character == 4
+      assert range.end.line == 5
+      assert range.end.character == String.length(expected_line)
+    end
+  end
+end

test/next_ls/commands/pipe_test.exs

@@ -82,4 +82,34 @@ defmodule NextLS.Commands.PipeTest do
       assert range["end"] == %{"character" => 27, "line" => 2}
     end)
   end
+
+  test "transforms pipes to function expressions", %{client: client, bar_path: bar} do
+    bar_uri = uri(bar)
+    id = 2
+
+    request client, %{
+      method: "workspace/executeCommand",
+      id: id,
+      jsonrpc: "2.0",
+      params: %{
+        command: "from-pipe",
+        arguments: [%{uri: bar_uri, position: %{line: 2, character: 0}}]
+      }
+    }
+
+    assert_request(client, "workspace/applyEdit", 500, fn params ->
+      assert %{"edit" => edit, "label" => "Pipe"} = params
+
+      assert %{
+               "changes" => %{
+                 ^bar_uri => [%{"newText" => text, "range" => range}]
+               }
+             } = edit
+
+      expected = "Enum.to_list(Map.new())"
+      assert text == expected
+      assert range["start"] == %{"character" => 8, "line" => 2}
+      assert range["end"] == %{"character" => 31, "line" => 2}
+    end)
+  end
 end