feat: allow merging of keymap preset with custom keymap (#233)

* feat: allow merging of keymap preset with custom keymap

* refactor: extract getting preset into function

* docs: remove duplciate keymap documentation

Author: kedom1337

README.md

@@ -161,15 +161,27 @@ MiniDeps.add({
 
 ```lua
 {
-  -- the keymap may be a preset ('default' | 'super-tab' | 'enter') OR a table of keys => command[]
-  -- when defining your own, no keybinds will be assigned automatically.
-  -- you may pass a function in the command array where returning true 
-  -- will prevent the next command from running
-  -- 
-  -- The "fallback" command will run the next non-blink keymap.
-  --   For example, to accept the current completion item with "enter", or create a new line, 
-  --   when the blink window is closed, you would define it as: 
-  --   ['<CR>'] = { 'accept', 'fallback' }
+  -- The keymap can be:
+  --   - A preset ('default' | 'super-tab' | 'enter')
+  --   - A table of keys => command[]
+  --   - A table that includes a 'preset' key and custom key mappings
+  --
+  -- When specifying 'preset' in the keymap table, the custom key mappings are merged with the preset,
+  -- and any conflicting keys will overwrite the preset mappings.
+  --
+  -- Example:
+  --
+  -- keymap = {
+  --   preset = 'default',
+  --   ['<cr>'] = { 'select_and_accept', 'fallback' },
+  -- },
+  --
+  -- In this example, the 'default' preset is used, and the `<cr>` key mapping is added or overwrites the existing one from the preset.
+  -- When defining your own keymaps without a preset, no keybinds will be assigned automatically.
+  --
+  -- Available commands:
+  --   show, hide, accept, select_and_accept, select_prev, select_next, show_documentation, hide_documentation,
+  --   scroll_documentation_up, scroll_documentation_down, snippet_forward, snippet_backward, fallback
   --
   -- "default" keymap
   --   ['<C-space>'] = { 'show', 'show_documentation', 'hide_documentation' },
@@ -227,10 +239,6 @@ MiniDeps.add({
   --
   --   ['<C-b>'] = { 'scroll_documentation_up', 'fallback' },
   --   ['<C-f>'] = { 'scroll_documentation_down', 'fallback' },
-  --
-  -- available commands:
-  --   show, hide, accept, select_and_accept, select_prev, select_next, show_documentation, hide_documentation,
-  --   scroll_documentation_up, scroll_documentation_down, snippet_forward, snippet_backward, fallback
   keymap = 'default',
 
   accept = {

lua/blink/cmp/keymap.lua

@@ -88,19 +88,22 @@ function keymap.setup(opts)
         error('The blink.cmp keymap recently got reworked. Please see the README for the updated configuration')
       end
     end
+
+    -- Handle preset inside table
+    if opts.preset then
+      local preset_keymap = keymap.get_preset_keymap(opts.preset)
+
+      -- Remove 'preset' key from opts to prevent it from being treated as a keymap
+      opts.preset = nil
+      -- Merge the preset keymap with the user-defined keymaps
+      -- User-defined keymaps overwrite the preset keymaps
+      mappings = vim.tbl_extend('force', preset_keymap, opts)
+    end
   end
 
   -- handle presets
   if type(opts) == 'string' then
-    if opts == 'default' then
-      mappings = default_keymap
-    elseif opts == 'super-tab' then
-      mappings = super_tab_keymap
-    elseif opts == 'enter' then
-      mappings = enter_keymap
-    else
-      error('Invalid blink.cmp keymap preset: ' .. opts)
-    end
+    mappings = keymap.get_preset_keymap(opts)
   end
 
   -- we set on the buffer directly to avoid buffer-local keymaps (such as from autopairs)
@@ -114,6 +117,24 @@ function keymap.setup(opts)
   })
 end
 
+--- Gets the preset keymap for the given preset name
+--- @param preset_name string
+--- @return table
+function keymap.get_preset_keymap(preset_name)
+  local mappings
+  if preset_name == 'default' then
+    mappings = default_keymap
+  elseif preset_name == 'super-tab' then
+    mappings = super_tab_keymap
+  elseif preset_name == 'enter' then
+    mappings = enter_keymap
+  else
+    error('Invalid blink.cmp keymap preset: ' .. preset_name)
+  end
+
+  return mappings
+end
+
 --- Applies the keymaps to the current buffer
 --- @param keys_to_commands table<string, blink.cmp.KeymapCommand[]>
 function keymap.apply_keymap_to_current_buffer(keys_to_commands)