Language Server Specific Samples

Golang (gopls)

require('packer').startup(function(use) 
  --packer
  use 'wbthomason/packer.nvim'

  --lsp
  use 'neovim/nvim-lspconfig'

  --audo complete
  use 'hrsh7th/cmp-nvim-lsp'
  use 'hrsh7th/cmp-buffer'
  use 'hrsh7th/cmp-path'
  use 'hrsh7th/cmp-cmdline'
  use 'hrsh7th/nvim-cmp'
  --
  use 'hrsh7th/cmp-vsnip'
  use 'hrsh7th/vim-vsnip'
  vim.opt.completeopt = { "menu", "menuone", "noselect" }
end)

local has_words_before = function()
  local line, col = unpack(vim.api.nvim_win_get_cursor(0))
  return col ~= 0 and vim.api.nvim_buf_get_lines(0, line - 1, line, true)[1]:sub(col, col):match("%s") == nil
end

local feedkey = function(key, mode)
  vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes(key, true, true, true), mode, true)
end


local cmp = require('cmp')

cmp.setup({
  snippet = {
    expand = function(args)
      vim.fn["vsnip#anonymous"](args.body) -- For `vsnip` users.
    end,
  },
  mapping = {
    ['<CR>'] = cmp.mapping.confirm({ select = true }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
    ["<Tab>"] = cmp.mapping(function(fallback)
      if cmp.visible() then
        cmp.select_next_item()
      elseif vim.fn["vsnip#available"](1) == 1 then
        feedkey("<Plug>(vsnip-expand-or-jump)", "")
      elseif has_words_before() then
        cmp.complete()
      else
        fallback() -- The fallback function sends a already mapped key. In this case, it's probably `<Tab>`.
      end
    end, { "i", "s" }),
    ["<S-Tab>"] = cmp.mapping(function()
      if cmp.visible() then
        cmp.select_prev_item()
      elseif vim.fn["vsnip#jumpable"](-1) == 1 then
        feedkey("<Plug>(vsnip-jump-prev)", "")
      end
    end, { "i", "s" }),
  },
  sources = cmp.config.sources({
    { name = 'nvim_lsp' },
    { name = 'vsnip' }, -- For vsnip users.
  }, {
    { name = 'buffer' },
  })
})


local capabilities = require('cmp_nvim_lsp').update_capabilities(vim.lsp.protocol.make_client_capabilities()) --nvim-cmp
capabilities.textDocument.completion.completionItem.snippetSupport = true

local on_attach = function(client, bufnr)
  local function buf_set_keymap(...) vim.api.nvim_buf_set_keymap(bufnr, ...) end
  local function buf_set_option(...) vim.api.nvim_buf_set_option(bufnr, ...) end

  buf_set_option('omnifunc', 'v:lua.vim.lsp.omnifunc')
end

-- Setup lspconfig.
local nvim_lsp = require('lspconfig')

-- setup languages 
-- GoLang
nvim_lsp['gopls'].setup{
  cmd = {'gopls'},
  on_attach = on_attach,
  capabilities = capabilities,
  settings = {
    gopls = {
      experimentalPostfixCompletions = true,
      analyses = {
        unusedparams = true,
        shadow = true,
      },
      staticcheck = true,
    },
  },
  init_options = {
    usePlaceholders = true,
  }
}