Add a switch for swapping the rewrite direction of lemmas.

I have no idea why I can't get all these tests to pass, somehow the
regex isn't matching only all previous elements.

ftplugin/lean/switch.lua

@@ -41,15 +41,22 @@ vim.b.switch_definitions = {
   { 'ℕ', 'ℚ', 'ℝ', 'ℂ' },
 
   {
-    [ [=[\<simp\(?\?\)\(\s\+only\s\+\[[^\]]*]\)\?]=] ] = function(original)
+    [ [=[\<rw \[\%(\s*←\?\s*\i\+\s*,\s*\)*\zs\s*\(←\?\s*\)\(\i\+\)]=] ] = function (original)
+      local arrow = original[2]
+      local lemma = original[3]
+      return (arrow == '' and '← ' or '') .. lemma
+    end
+  },
+
+  {
+    [ [=[\<simp\(?\?\)\(\s\+only\s\+\[[^\]]*]\)\?]=] ] = function (original)
       if original[2] == '' and original[3] == '' then
         return 'simp?'
       else
         return 'simp'
       end
-    end,
+    end
   },
-
   { [segment 'bot'] = 'top', [segment 'top'] = 'bot' },
   { [segment 'inl'] = 'inr', [segment 'inr'] = 'inl' },
   { [segment 'left'] = 'right', [segment 'right'] = 'left' },

spec/switch_spec.lua

@@ -86,4 +86,65 @@ describe('tactics', function()
       assert.contents.are [=[simp? [foo, bar, baz]]=]
     end)
   )
+
+  it(
+    'switch between rw [foo] and rw [← foo]',
+    clean_buffer([=[rw [foo]]=], function()
+      vim.cmd.normal { '1gg5|', bang = true }
+      vim.cmd.Switch()
+      assert.contents.are [=[rw [← foo]]=]
+    end)
+  )
+
+  it(
+    'switch between rw [← foo] and rw [foo]',
+    clean_buffer([=[rw [← foo]]=], function()
+      vim.cmd.normal { '1gg5|', bang = true }
+      vim.cmd.Switch()
+      assert.contents.are [=[rw [foo]]=]
+    end)
+  )
+
+  it(
+    'switch between rw [foo, bar] and rw [← foo, bar]',
+    clean_buffer([=[rw [foo, bar]]=], function()
+      vim.cmd.normal { '1gg5|', bang = true }
+      vim.cmd.Switch()
+      assert.contents.are [=[rw [← foo, bar]]=]
+    end)
+  )
+
+  it(
+    'switch between rw [foo, bar, baz] and rw [foo, ← bar, baz]',
+    clean_buffer([=[rw [foo, bar, baz]]=], function()
+      vim.cmd.normal { '1gg11|', bang = true }
+
+      vim.cmd.Switch()
+      assert.contents.are [=[rw [foo, ← bar, baz]]=]
+
+      vim.cmd.Switch()
+      assert.contents.are [=[rw [foo, bar, baz]]=]
+
+      vim.cmd.normal { '1gg16|', bang = true }
+      assert.contents.are [=[rw [foo, bar, ← baz]]=]
+    end)
+  )
+
+  it(
+    'switch between rw [foo, bar] and rw [foo, ← bar]',
+    clean_buffer([=[rw [foo, bar]]=], function()
+      vim.cmd.normal { '1gg11|', bang = true }
+      vim.cmd.Switch()
+      assert.contents.are [=[rw [foo, ← bar]]=]
+    end)
+  )
+
+  it(
+    'switch between rw [foo _ bar, baz] and rw [← foo _ bar, baz]',
+    clean_buffer([=[rw [foo _ bar, baz]]=], function()
+      vim.cmd.normal { '1gg5|', bang = true }
+      vim.cmd.Switch()
+      assert.contents.are [=[rw [← foo _ bar, baz]]=]
+    end)
+  )
 end)