nvim/plug: improve cmdline (:) completions

This commit enables nvim-cmp's cmdline completion support, overriding
the builtin neovim's.

We gain a nicer menu, more sources (paths, history), and a slightly more
intelligent listing with some support for file specific commands (e, r,
w).

We also switch out the 'path' completion source with 'async_path',
preventing delays / freezes when traversing slow or large fs trees

nvim/lua/psoxizsh/plugins/config/nvim-cmp.lua

@@ -45,7 +45,6 @@ return function()
       ['<C-Space>']   = kmap.confirm({ behavior = cmp.ConfirmBehavior.Insert, select = true }),
   }
   defaults.mapping = mode.insert(defaults.mapping)
-  defaults.mapping = mode.cmd(defaults.mapping)
 
   -- Sources of auto completion
   --
@@ -53,7 +52,7 @@ return function()
   -- that is, 'path's will be shown before 'nvim_lsp's, etc
   defaults.sources = sources(
     {
-      { name = 'path',                                            },
+      { name = 'async_path',                                      },
     },
     {
       { name = 'nvim_lsp',                    keyword_length = 2  },
@@ -91,4 +90,29 @@ return function()
   }
 
   cmp.setup(util.mconfig('config.nvim-cmp', defaults))
+
+  cmp.setup.cmdline(':', {
+    mapping = mode.cmd(),
+    sources = sources(
+      {
+        { name = 'async_path',        max_item_count = 2 },
+      },
+      {
+        { name = 'cmdline_history',   max_item_count = 2 },
+        { name = 'cmdline',           max_item_count = 6 },
+      }
+    )
+  })
+
+  cmp.setup.cmdline({'/', '?', '@'}, {
+    mapping = mode.cmd(),
+    sources = sources(
+      {
+        { name = 'cmdline_history',   max_item_count = 1 },
+      },
+      {
+        { name = 'buffer',            max_item_count = 9 },
+      }
+    )
+  })
 end

nvim/lua/psoxizsh/plugins/plug.lua

@@ -149,8 +149,10 @@ local plugins = {
 
   -- Other sources:
   { 'hrsh7th/cmp-vsnip' },
-  { 'hrsh7th/cmp-path' },
+  { 'FelipeLema/cmp-async-path' },
   { 'hrsh7th/cmp-buffer' },
+  { 'hrsh7th/cmp-cmdline' },
+  { 'dmitmel/cmp-cmdline-history' },
   { 'f3fora/cmp-spell',
       after = { 'lspconfig' },
       config = require 'psoxizsh.plugins.config.cmp-spell'