From c1251a34252de09e46f98135f30a6fd90327a234 Mon Sep 17 00:00:00 2001
From: Dorgan <dorgandash@gmail.com>
Date: Thu, 4 Jan 2024 20:45:47 -0300
Subject: [PATCH] Fix incorrect ranges for `fn` and `->` (#117)

Fixes #116
---
 lib/sourceror/range.ex | 35 ++++++++++++++++++++++++++++++++++-
 test/range_test.exs    | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/lib/sourceror/range.ex b/lib/sourceror/range.ex
index f6e1fc6..285dc1d 100644
--- a/lib/sourceror/range.ex
+++ b/lib/sourceror/range.ex
@@ -199,7 +199,31 @@ defmodule Sourceror.Range do
     get_range(first)
   end
 
-  # Stabs without args
+  # Stabs without right args
+  # a ->
+  defp do_get_range({:->, stab_meta, [left, {:__block__, right_meta, [nil]} = right]}) do
+    end_pos =
+      if right_meta[:column] == stab_meta[:column] do
+        right_meta
+        |> Keyword.take([:line, :column])
+        |> Keyword.update!(:column, &(&1 + 2))
+      else
+        get_range(right).end
+      end
+
+    start_pos =
+      case left do
+        [] ->
+          Keyword.take(stab_meta, [:line, :column])
+
+        _ ->
+          get_range(left).start
+      end
+
+    %{start: start_pos, end: end_pos}
+  end
+
+  # Stabs without left args
   # -> b
   defp do_get_range({:->, meta, [[], right]}) do
     start_pos = Keyword.take(meta, [:line, :column])
@@ -425,6 +449,15 @@ defmodule Sourceror.Range do
     end
   end
 
+  defp get_range_for_node_with_closing_line({:fn, _, _} = quoted) do
+    start_position = Sourceror.get_start_position(quoted)
+    end_position = Sourceror.get_end_position(quoted)
+
+    end_position = Keyword.update!(end_position, :column, &(&1 + 3))
+
+    %{start: start_position, end: end_position}
+  end
+
   defp get_range_for_node_with_closing_line({_, meta, _} = quoted) do
     start_position = Sourceror.get_start_position(quoted)
     end_position = Sourceror.get_end_position(quoted)
diff --git a/test/range_test.exs b/test/range_test.exs
index e1b867d..6943eeb 100644
--- a/test/range_test.exs
+++ b/test/range_test.exs
@@ -336,6 +336,48 @@ defmodule SourcerorTest.RangeTest do
              }
     end
 
+    test "stab without body" do
+      {:fn, _, [stab]} = Sourceror.parse_string!(~S"fn -> end")
+
+      assert Sourceror.Range.get_range(stab) == %{
+               start: [line: 1, column: 4],
+               end: [line: 1, column: 6]
+             }
+
+      {:fn, _, [stab]} =
+        Sourceror.parse_string!(~S"""
+        fn a ->
+        end
+        """)
+
+      assert Sourceror.Range.get_range(stab) == %{
+               start: [line: 1, column: 4],
+               end: [line: 1, column: 8]
+             }
+    end
+
+    test "anonymous functions" do
+      assert to_range(~S"fn -> :ok end") == %{
+               start: [line: 1, column: 1],
+               end: [line: 1, column: 14]
+             }
+
+      assert to_range(~S"""
+             fn ->
+               :ok
+             end
+             """) == %{start: [line: 1, column: 1], end: [line: 3, column: 4]}
+
+      assert to_range(~S"""
+             fn -> end
+             """) == %{start: [line: 1, column: 1], end: [line: 1, column: 10]}
+
+      assert to_range(~S"""
+             fn ->
+             end
+             """) == %{start: [line: 1, column: 1], end: [line: 2, column: 4]}
+    end
+
     test "qualified tuples" do
       assert to_range(~S/Foo.{Bar, Baz}/) == %{
                start: [line: 1, column: 1],