fix: parse newline ternary continuation after ellipsis

Ellipsis was treated as standalone before `//` when the ternary operator arrived with newline metadata, producing a mismatched AST for forms like `x...\n//y`.

Detect newline-associated ternary continuation and keep existing semicolon-separated behavior intact (e.g. `x...;//y`).

Adds a regression assertions in the property-regression test block.

Author: mkaput

lib/spitfire.ex

@@ -2920,14 +2920,18 @@ defmodule Spitfire do
 
   defp parse_ellipsis_op(parser) do
     trace "parse_ellipsis_op", trace_meta(parser) do
-      peek = peek_token_type(parser)
-
-      # `...` is standalone when followed by a terminal, stab op, keyword
-      # or binary operators (except :dual_op)
-      if MapSet.member?(@terminals_with_comma, peek_token(parser)) or
-           peek_token(parser) == :";" or
-           peek in [:stab_op, :do, :end, :block_identifier] or
-           (is_binary_op?(peek) and peek != :dual_op) do
+      peek_type = peek_token_type(parser)
+      peek = peek_token(parser)
+
+      standalone? =
+        MapSet.member?(@terminals_with_comma, peek) or
+          peek == :";" or
+          peek_type in [:stab_op, :do, :end, :block_identifier] or
+          (is_binary_op?(peek_type) and peek_type != :dual_op)
+
+      # `...` is standalone when followed by a terminal, stab op, keyword,
+      # or binary operator (except :dual_op), unless it continues a newline ternary (`//`).
+      if standalone? and not newline_ternary_continuation?(parser) do
         {{:..., current_meta(parser), []}, parser}
       else
         meta = current_meta(parser)
@@ -2953,6 +2957,22 @@ defmodule Spitfire do
     end
   end
 
+  defp newline_ternary_continuation?(parser) do
+    cond do
+      peek_token(parser) == :eol ->
+        peek_token_skip_eoe(parser) == :ternary_op
+
+      peek_token_type(parser) == :ternary_op ->
+        case parser |> next_token() |> current_newlines() do
+          nl when is_integer(nl) and nl > 0 -> true
+          _ -> false
+        end
+
+      true ->
+        false
+    end
+  end
+
   # Formats a struct type AST to a string for error messages
   defp format_struct_type({:__aliases__, _, parts}) do
     Enum.map_join(parts, ".", fn

test/spitfire_test.exs

@@ -2300,6 +2300,10 @@ defmodule SpitfireTest do
       assert Spitfire.parse("%e.(){}") == s2q("%e.(){}")
       assert Spitfire.parse("%e.(1){}") == s2q("%e.(1){}")
       assert Spitfire.parse("%e.(a, b){}") == s2q("%e.(a, b){}")
+
+      # Ellipsis + ternary edge cases (newline and semicolon-separated)
+      assert Spitfire.parse("x...\n//y") == s2q("x...\n//y")
+      assert Spitfire.parse("x...;//y") == s2q("x...;//y")
     end
   end