fix: recover from incomplete keyword lists (#71)

Author: doorgan

lib/spitfire.ex

@@ -653,13 +653,7 @@ defmodule Spitfire do
 
       {value, parser} = parse_expression(parser, @kw_identifier, false, false, false)
 
-      {kvs, parser} =
-        while2 peek_token(parser) == :"," <- parser do
-          parser = parser |> next_token() |> next_token()
-          {pair, parser} = parse_kw_identifier(parser)
-
-          {pair, parser}
-        end
+      {kvs, parser} = parse_kw_list_continuation(parser)
 
       {[{token, value} | kvs], parser}
     end
@@ -680,18 +674,39 @@ defmodule Spitfire do
 
       {value, parser} = parse_expression(parser, @kw_identifier, false, false, false)
 
-      {kvs, parser} =
-        while2 peek_token(parser) == :"," <- parser do
-          parser = parser |> next_token() |> next_token()
-          {pair, parser} = parse_kw_identifier(parser)
-
-          {pair, parser}
-        end
+      {kvs, parser} = parse_kw_list_continuation(parser)
 
       {[{atom, value} | kvs], parser}
     end
   end
 
+  defp parse_kw_list_continuation(parser) do
+    while2 peek_token(parser) == :"," <- parser do
+      parser = parser |> next_token() |> next_token()
+
+      case current_token_type(parser) do
+        type when type in [:kw_identifier, :kw_identifier_unsafe] ->
+          parse_kw_identifier(parser)
+
+        _ ->
+          parser =
+            if match?({:paren_identifier, _, :__cursor__}, parser.current_token) do
+              parser
+            else
+              put_error(
+                parser,
+                {current_meta(parser),
+                 "unexpected expression after keyword list. Keyword lists must always come as the last argument. " <>
+                   "Therefore, this is not allowed:\n\n    function_call(1, some: :option, 2)\n\n" <>
+                   "Instead, wrap the keyword in brackets:\n\n    function_call(1, [some: :option], 2)"}
+              )
+            end
+
+          parse_expression(parser, @kw_identifier, true, false, false)
+      end
+    end
+  end
+
   defp parse_assoc_op(%{current_token: {:assoc_op, _, _token}} = parser, key) do
     trace "parse_assoc_op", trace_meta(parser) do
       assoc_meta = current_meta(parser)

test/spitfire_test.exs

@@ -2844,6 +2844,31 @@ defmodule SpitfireTest do
       assert {:ok, _} = Spitfire.parse(code)
     end
 
+    test "unexpected expression after keyword list" do
+      assert {:error, _ast, errors} = Spitfire.parse(~S|foo(a: 1, b)|)
+
+      assert Enum.any?(errors, fn {_, msg} ->
+               String.contains?(msg, "unexpected expression after keyword list")
+             end)
+
+      assert {:error, _ast, errors} = Spitfire.parse(~S|foo(a: 1, :bar)|)
+
+      assert Enum.any?(errors, fn {_, msg} ->
+               String.contains?(msg, "unexpected expression after keyword list")
+             end)
+
+      assert {:error, _ast, errors} = Spitfire.parse(~S|@tag foo: bar, baz|)
+
+      assert Enum.any?(errors, fn {_, msg} ->
+               String.contains?(msg, "unexpected expression after keyword list")
+             end)
+    end
+
+    test "__cursor__ after keyword list does not crash" do
+      code = ~S|foo(a: 1, __cursor__())|
+      assert {:ok, {:foo, _, [[{:a, 1}, {:__cursor__, _, []}]]}} = Spitfire.parse(code)
+    end
+
     test "weird characters" do
       code = """
       [«]