config: nvim: add basic autocompletion and snippet collection

config/nvim/lua/plugins.lua

@@ -43,6 +43,53 @@ return require('packer').startup({
 			config = function() require('colorizer').setup() end,
 		}
 
+		--------------------
+		-- Snippets
+		--------------------
+		use { -- snippet engine
+			'L3MON4D3/LuaSnip',
+			requires = {
+				'saadparwaiz1/cmp_luasnip',
+				'rafamadriz/friendly-snippets',
+			},
+		}
+		use { -- various snippets
+			'rafamadriz/friendly-snippets',
+			after = { 'LuaSnip' },
+			config = load_config('friendly-snippets'),
+		}
+
+		--------------------
+		-- Completion
+		--------------------
+		use { -- nvim-cmp source for LuaSnip
+			'saadparwaiz1/cmp_luasnip',
+			requires = { 'hrsh7th/nvim-cmp' },
+			after = { 'LuaSnip' },
+		}
+		use { -- nvim-cmp source for buffer words
+			'hrsh7th/cmp-buffer',
+			requires = { 'hrsh7th/nvim-cmp' },
+		}
+		use { -- nvim-cmp source for filesystem paths
+			'hrsh7th/cmp-path',
+			requires = { 'hrsh7th/nvim-cmp' },
+		}
+		use { -- nvim-cmp source for vim's cmdline
+			'hrsh7th/cmp-cmdline',
+			requires = { 'hrsh7th/nvim-cmp' },
+		}
+		use { -- completion engine
+			'hrsh7th/nvim-cmp',
+			after = {
+				'cmp-buffer',
+				'cmp-path',
+				'cmp-cmdline',
+				'cmp_luasnip'
+			},
+			config = load_config('nvim-cmp'),
+		}
+
 		-- Automatically set up your configuration after cloning packer.nvim
 		-- Put this at the end after all plugins
 		if packer_bootstrap then

config/nvim/lua/plugins/friendly-snippets.lua

@@ -0,0 +1 @@
+require('luasnip.loaders.from_vscode').lazy_load()

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

@@ -0,0 +1,61 @@
+vim.opt.completeopt = 'menu,menuone,noselect'
+-- make 'kind' readable with dichromatic colorscheme
+vim.cmd('highlight! CmpItemKindDefault guibg=NONE guifg=#000000')
+
+local cmp = require('cmp')
+cmp.setup({
+	snippet = {
+		expand = function(args)
+			require('luasnip').lsp_expand(args.body)
+		end,
+	},
+	formatting = {
+		format = function(entry, vim_item)
+			vim_item.menu = ({
+				buffer = '[Buffer]',
+				luasnip = '[Snippet]',
+			})[entry.source.name]
+			return vim_item
+		end,
+	},
+	mapping = cmp.mapping.preset.insert({
+		['<C-b>'] = cmp.mapping.scroll_docs(-4),
+		['<C-f>'] = cmp.mapping.scroll_docs(4),
+		['<C-Space>'] = cmp.mapping.complete(),
+		['<C-e>'] = cmp.mapping.abort(),
+		['<CR>'] = cmp.mapping.confirm({ select = true }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
+	}),
+	sources = cmp.config.sources({
+		{ name = 'nvim_lsp', keyword_length = 3 },
+		{ name = 'luasnip', keyword_length = 2 },
+	}, {
+		{ name = 'buffer', keyword_length = 3 },
+	})
+})
+
+-- configure completion for specific filetype
+cmp.setup.filetype('gitcommit', {
+	sources = cmp.config.sources({
+		{ name = 'buffer' },
+	}),
+})
+
+-- use buffer source for `/` and `?` (if you enabled `native_menu`, this won't
+-- work anymore)
+cmp.setup.cmdline({ '/', '?' }, {
+	mapping = cmp.mapping.preset.cmdline(),
+	sources = {
+		{ name = 'buffer' }
+	},
+})
+
+-- use cmdline & path source for ':' (if you enabled `native_menu`, this won't
+-- work anymore).
+cmp.setup.cmdline(':', {
+	mapping = cmp.mapping.preset.cmdline(),
+	sources = cmp.config.sources({
+		{ name = 'path' }
+	}, {
+		{ name = 'cmdline' }
+	}),
+})