neovim: lsp autocompletion

common/home-manager.nix

@@ -58,12 +58,15 @@
 
         plugins = with pkgs.vimPlugins; [
           bufferline-nvim
+          cmp-nvim-lsp
+          cmp_luasnip
           galaxyline-nvim
           indentLine
           lualine-nvim
+          luasnip
           neorg
+          nvim-cmp
           nvim-colorizer-lua
-          nvim-compe
           nvim-lspconfig
           nvim-tree-lua
           nvim-treesitter

common/nvim.lua

@@ -93,9 +93,59 @@ local on_attach = function(client, bufnr)
   vim.keymap.set('n', '<space>f', vim.lsp.buf.formatting, bufopts)
 end
 
+
+local capabilities = vim.lsp.protocol.make_client_capabilities()
+capabilities = require("cmp_nvim_lsp").update_capabilities(capabilities)
+
 local lspconfig = require("lspconfig")
-lspconfig.rnix.setup { on_attach = on_attach }
-lspconfig.pyright.setup { on_attach = on_attach }
-lspconfig.rust_analyzer.setup { on_attach = on_attach }
+local servers = { "rnix", "pyright", "rust_analyzer" }
+for _, lsp in ipairs(servers) do
+  lspconfig[lsp].setup {
+    on_attach = on_attach,
+    capabilities = capabilities,
+  }
+end
+
+local luasnip = require("luasnip")
+
+local cmp = require("cmp")
+cmp.setup {
+  snippet = {
+    expand = function(args)
+      luasnip.lsp_expand(args.body)
+    end,
+  },
+  mapping = cmp.mapping.preset.insert({
+    ["<C-d>"] = cmp.mapping.scroll_docs(-4),
+    ["<C-f>"] = cmp.mapping.scroll_docs(4),
+    ["<C-Space>"] = cmp.mapping.complete(),
+    ["<CR>"] = cmp.mapping.confirm {
+      behavior = cmp.ConfirmBehavior.Replace,
+      select = true,
+    },
+    ["<Tab>"] = cmp.mapping(function(fallback)
+      if cmp.visible() then
+        cmp.select_next_item()
+      elseif luasnip.expand_or_jumpable() then
+        luasnip.expand_or_jump()
+      else
+        fallback()
+      end
+    end, { "i", "s" }),
+    ["<S-Tab>"] = cmp.mapping(function(fallback)
+      if cmp.visible() then
+        cmp.select_prev_item()
+      elseif luasnip.jumpable(-1) then
+        luasnip.jump(-1)
+      else
+        fallback()
+      end
+    end, { "i", "s" }),
+  }),
+  sources = {
+    { name = "nvim_lsp" },
+    { name = "luasnip" },
+  },
+}
 
 vim.api.nvim_set_keymap("n", "<C-b>", ":NvimTreeToggle<CR>", { noremap = true, silent = true })