feat: anonymous function capture syntax

Author: mhanberg

lib/spitfire.ex

@@ -162,6 +162,7 @@ defmodule Spitfire do
         :at_op -> &parse_prefix_expression/1
         :unary_op -> &parse_prefix_expression/1
         :capture_op -> &parse_prefix_expression/1
+        :capture_int -> &parse_prefix_expression/1
         :stab_op -> &parse_stab_expression/1
         :"[" -> &parse_list_literal/1
         :"(" -> &parse_grouped_expression/1
@@ -972,6 +973,7 @@ defmodule Spitfire do
              :xor_op,
              :in_match_op,
              :capture_op,
+             :capture_int,
              :in_op,
              :or_op,
              :and_op,

test/spitfire_test.exs

@@ -1061,7 +1061,17 @@ defmodule SpitfireTest do
        ''', {:&, [], [{:/, [], [{:foo, [], Elixir}, 1]}]}},
       {~s'''
        &Foo.foo/1
-       ''', {:&, [], [{:/, [], [{{:., [], [{:__aliases__, [], [:Foo]}, :foo]}, [], []}, 1]}]}}
+       ''', {:&, [], [{:/, [], [{{:., [], [{:__aliases__, [], [:Foo]}, :foo]}, [], []}, 1]}]}},
+      {~s'''
+       & &1
+       ''', {:&, [], [{:&, [], [1]}]}},
+      {~s'''
+       &Foo.bar(one, &1)
+       ''',
+       {:&, [],
+        [
+          {{:., [], [{:__aliases__, [], [:Foo]}, :bar]}, [], [{:one, [], Elixir}, {:&, [], [1]}]}
+        ]}}
     ]
 
     for {code, expected} <- codes do