keymap: Support <D-...> (super/command key).

Adds support for:
  - api:vim_input("<D-a>")
  - ":nnoremap <C-D-S-...>" and permutations thereof

UIs must capture the modifier and send it as "<D-...>" to vim_input().

Note: Before this commit, any arbitrary ":nnoremap <{foo}-{bar}>"
mapping could already be invoked with feedkeys("\<{foo}-{bar}>"). This
commit supports "D-" as a modifier that can be combined with "C-", "A-",
"S-" in any order.

For non-GUI (terminal) support, user must:
  :set <D-a>={CSI sequence}
then send the {CSI sequence} from their terminal. But this does not work
yet (regression #2204).

Closes #2190

1 files changed, 12 insertions, 4 deletions

diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index f4a9ddc698..9c9759adf6 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -144,15 +144,23 @@ describe('vim_* functions', function()
 
   describe('replace_termcodes', function()
     it('escapes K_SPECIAL as K_SPECIAL KS_SPECIAL KE_FILLER', function()
-      eq(helpers.nvim('replace_termcodes', '\128', true, true, true), '\128\254X')
+      eq('\128\254X', helpers.nvim('replace_termcodes', '\128', true, true, true))
     end)
 
-    it('leaves non K_SPECIAL string unchanged', function()
-      eq(helpers.nvim('replace_termcodes', 'abc', true, true, true), 'abc')
+    it('leaves non-K_SPECIAL string unchanged', function()
+      eq('abc', helpers.nvim('replace_termcodes', 'abc', true, true, true))
     end)
 
     it('converts <expressions>', function()
-      eq(helpers.nvim('replace_termcodes', '<Leader>', true, true, true), '\\')
+      eq('\\', helpers.nvim('replace_termcodes', '<Leader>', true, true, true))
+    end)
+
+    it('converts <LeftMouse> to K_SPECIAL KS_EXTRA KE_LEFTMOUSE', function()
+      -- K_SPECIAL KS_EXTRA KE_LEFTMOUSE
+      -- 0x80      0xfd     0x2c
+      -- 128       253      44
+      eq('\128\253\44', helpers.nvim('replace_termcodes',
+                                     '<LeftMouse>', true, true, true))
     end)
   end)