vim: improve completion, add cmdline completion on demand

config/nvim/lua/user/plugins/completion.lua

@@ -1,62 +1,65 @@
 local config = function()
   local cmp = require('cmp')
 
-  local mapping = {
+  local map = setmetatable({
-    ['<c-n>'] = {
+    complete_or_select_next = function()
-      i = function()
       if cmp.visible() then
         cmp.select_next_item { behavior = cmp.SelectBehavior.Select }
       else
         cmp.complete()
       end
     end,
-    },
 
-    ['<c-p>'] = {
+    complete_or_select_previous = function()
-      i = function()
       if cmp.visible() then
         cmp.select_prev_item { behavior = cmp.SelectBehavior.Select }
       else
         cmp.complete()
       end
     end,
-    },
 
-    ['<Down>'] = { i = cmp.mapping.select_next_item { behavior = cmp.SelectBehavior.Select } },
+    tab_completion = function(fallback)
-    ['<Up>'] = { i = cmp.mapping.select_prev_item { behavior = cmp.SelectBehavior.Select } },
-
-    ['<c-f>'] = { i = cmp.mapping.scroll_docs(4) },
-    ['<c-b>'] = { i = cmp.mapping.scroll_docs(-4) },
-
-    ['<c-e>'] = { i = cmp.mapping.abort() },
-    ['<c-y>'] = { i = cmp.mapping.confirm { select = true } },
-    ['<Tab>'] = {
-      i = function(fallback)
       if cmp.visible() then
-          cmp.confirm { select = true }
+        cmp.complete_common_string()
+      elseif vim.fn.mode() == 'c' then
+        cmp.complete()
       else
         fallback()
       end
     end,
-    },
+  }, {
+    -- Make `func` available in [i]nsert and [c]mdline modes.
+    __call = function(_, func) return { i = func, c = func } end
+  })
+
+  local keymap = {
+    ['<c-n>']     = map(map.complete_or_select_next),
+    ['<c-p>']     = map(map.complete_or_select_previous),
+
+    ['<down>']    = map(cmp.mapping.select_next_item { behavior = cmp.SelectBehavior.Select }),
+    ['<up>']      = map(cmp.mapping.select_prev_item { behavior = cmp.SelectBehavior.Select }),
+
+    ['<c-f>']     = map(cmp.mapping.scroll_docs(4)),
+    ['<s-down>']  = map(cmp.mapping.scroll_docs(4)),
+    ['<c-b>']     = map(cmp.mapping.scroll_docs(-4)),
+    ['<s-up>']    = map(cmp.mapping.scroll_docs(-4)),
+
+    ['<c-e>']     = map(cmp.mapping.abort()),
+    ['<c-y>']     = map(cmp.mapping.confirm { select = true }),
+    ['<tab>']     = map(map.tab_completion),
   }
 
   cmp.setup {
-    mapping = mapping,
+    mapping = keymap,
 
-    sources = cmp.config.sources({
+    snippet = {
-      { name = 'nvim_lsp' },
+      expand = function(_ --[[args]])
-      { name = 'nvim_lua' },
+        -- require('luasnip').lsp_expand(args.body) TODO enable
-    }, {
+      end,
-      { name = 'path' },
+    },
-      { name = 'buffer', keyword_length = 5 },
-    }),
 
-    formatting = (function()
+    formatting = {
-      local ok, lspkind = pcall(require, 'lspkind')
+      format = require('lspkind').cmp_format {
-      if not ok then return {} end
-      return {
-        format = lspkind.cmp_format {
         mode = 'symbol_text',
         menu = {
           buffer   = "[buf]",
@@ -65,13 +68,40 @@ local config = function()
           path     = "[path]",
         },
       },
-      }
+    },
-    end)(),
+
+    sources = cmp.config.sources({
+      { name = 'nvim_lua' },
+      { name = 'nvim_lsp' },
+      -- { name = "luasnip" }, TODO enable
+    }, {
+      { name = 'path' },
+      { name = 'buffer', keyword_length = 5 },
+    }),
+
+    window = {
+        completion = cmp.config.window.bordered(),
+        documentation = cmp.config.window.bordered(),
+    },
 
     experimental = {
       ghost_text = true,
     },
   }
+
+  cmp.setup.cmdline(':', {
+    mapping = keymap,
+
+    completion = {
+      autocomplete = false,
+    },
+
+    sources = cmp.config.sources({
+      { name = 'path' }
+    }, {
+      { name = 'cmdline' }
+    }),
+  })
 end
 
 return {
@@ -83,6 +113,7 @@ return {
     'hrsh7th/cmp-nvim-lua',
     'hrsh7th/cmp-path',
     'hrsh7th/cmp-buffer',
+    'hrsh7th/cmp-cmdline',
     'onsails/lspkind-nvim',
   },
 }