nvim-lspconfig + nvim-cmp setup

init.lua

--[[
  blogpost:
  https://vonheikemen.github.io/devlog/tools/setup-nvim-lspconfig-plus-nvim-cmp/

  Dependencies:
  LSP:
  https://github.com/neovim/nvim-lspconfig
  https://github.com/williamboman/mason.nvim             (optional)
  https://github.com/williamboman/mason-lspconfig.nvim   (optional)

  Completion:
  https://github.com/hrsh7th/nvim-cmp
  https://github.com/hrsh7th/cmp-nvim-lsp
  https://github.com/hrsh7th/cmp-buffer
  https://github.com/hrsh7th/cmp-path
  https://github.com/saadparwaiz1/cmp_luasnip
  
  Snippets:
  https://github.com/L3MON4D3/LuaSnip
  https://github.com/rafamadriz/friendly-snippets
]]

---
-- Keybindings
---

vim.api.nvim_create_autocmd('LspAttach', {
  desc = 'LSP actions',
  callback = function()
    local bufmap = function(mode, lhs, rhs)
      local opts = {buffer = true}
      vim.keymap.set(mode, lhs, rhs, opts)
    end

    bufmap('n', 'K', '<cmd>lua vim.lsp.buf.hover()<cr>')
    bufmap('n', 'gd', '<cmd>lua vim.lsp.buf.definition()<cr>')
    bufmap('n', 'gD', '<cmd>lua vim.lsp.buf.declaration()<cr>')
    bufmap('n', 'gi', '<cmd>lua vim.lsp.buf.implementation()<cr>')
    bufmap('n', 'go', '<cmd>lua vim.lsp.buf.type_definition()<cr>')
    bufmap('n', 'gr', '<cmd>lua vim.lsp.buf.references()<cr>')
    bufmap('n', 'gs', '<cmd>lua vim.lsp.buf.signature_help()<cr>')
    bufmap('n', '<F2>', '<cmd>lua vim.lsp.buf.rename()<cr>')
    bufmap('n', '<F3>', '<cmd>lua vim.lsp.buf.format({async = true})<cr>')
    bufmap('n', '<F4>', '<cmd>lua vim.lsp.buf.code_action()<cr>')
    bufmap('n', 'gl', '<cmd>lua vim.diagnostic.open_float()<cr>')
    bufmap('n', '[d', '<cmd>lua vim.diagnostic.goto_prev()<cr>')
    bufmap('n', ']d', '<cmd>lua vim.diagnostic.goto_next()<cr>')
  end
})


---
-- Diagnostics
---

local sign = function(opts)
  vim.fn.sign_define(opts.name, {
    texthl = opts.name,
    text = opts.text,
    numhl = ''
  })
end

sign({name = 'DiagnosticSignError', text = '✘'})
sign({name = 'DiagnosticSignWarn', text = '▲'})
sign({name = 'DiagnosticSignHint', text = '⚑'})
sign({name = 'DiagnosticSignInfo', text = ''})

vim.diagnostic.config({
  virtual_text = false,
  severity_sort = true,
  float = {
    border = 'rounded',
    source = 'always',
  },
})

vim.lsp.handlers['textDocument/hover'] = vim.lsp.with(
  vim.lsp.handlers.hover,
  {border = 'rounded'}
)

vim.lsp.handlers['textDocument/signatureHelp'] = vim.lsp.with(
  vim.lsp.handlers.signature_help,
  {border = 'rounded'}
)

---
-- LSP servers
---

-- require('mason').setup({})
-- require('mason-lspconfig').setup({})

local lspconfig = require('lspconfig')
local lsp_capabilities = require('cmp_nvim_lsp').default_capabilities()

lspconfig.tsserver.setup({
  capabilities = lsp_capabilities,
})
lspconfig.lua_ls.setup({
  capabilities = lsp_capabilities,
})


---
-- Autocomplete
---
vim.opt.completeopt = {'menu', 'menuone', 'noselect'}

require('luasnip.loaders.from_vscode').lazy_load()

local cmp = require('cmp')
local luasnip = require('luasnip')

local select_opts = {behavior = cmp.SelectBehavior.Select}

cmp.setup({
  snippet = {
    expand = function(args)
      luasnip.lsp_expand(args.body)
    end
  },
  sources = {
    {name = 'path'},
    {name = 'nvim_lsp', keyword_length = 1},
    {name = 'buffer', keyword_length = 3},
    {name = 'luasnip', keyword_length = 2},
  },
  window = {
    documentation = cmp.config.window.bordered()
  },
  formatting = {
    fields = {'menu', 'abbr', 'kind'},
    format = function(entry, item)
      local menu_icon = {
        nvim_lsp = 'λ',
        luasnip = '⋗',
        buffer = 'Ω',
        path = '🖫',
      }

      item.menu = menu_icon[entry.source.name]
      return item
    end,
  },
  mapping = {
    ['<Up>'] = cmp.mapping.select_prev_item(select_opts),
    ['<Down>'] = cmp.mapping.select_next_item(select_opts),

    ['<C-p>'] = cmp.mapping.select_prev_item(select_opts),
    ['<C-n>'] = cmp.mapping.select_next_item(select_opts),

    ['<C-u>'] = cmp.mapping.scroll_docs(-4),
    ['<C-d>'] = cmp.mapping.scroll_docs(4),

    ['<C-e>'] = cmp.mapping.abort(),
    ['<C-y>'] = cmp.mapping.confirm({select = true}),
    ['<CR>'] = cmp.mapping.confirm({select = false}),

    ['<C-f>'] = cmp.mapping(function(fallback)
      if luasnip.jumpable(1) then
        luasnip.jump(1)
      else
        fallback()
      end
    end, {'i', 's'}),

    ['<C-b>'] = cmp.mapping(function(fallback)
      if luasnip.jumpable(-1) then
        luasnip.jump(-1)
      else
        fallback()
      end
    end, {'i', 's'}),

    ['<Tab>'] = cmp.mapping(function(fallback)
      local col = vim.fn.col('.') - 1

      if cmp.visible() then
        cmp.select_next_item(select_opts)
      elseif col == 0 or vim.fn.getline('.'):sub(col, col):match('%s') then
        fallback()
      else
        cmp.complete()
      end
    end, {'i', 's'}),

    ['<S-Tab>'] = cmp.mapping(function(fallback)
      if cmp.visible() then
        cmp.select_prev_item(select_opts)
      else
        fallback()
      end
    end, {'i', 's'}),
  },
})

@VonHeikemen Several language servers have asked me to enable an additional capability in my lsp configuration.

capabilities.textDocument.completion.completionItem.snippetSupport = true,

I haven't figured out how to work this into the current configuration schema, or even if it is needed. If this is needed to be added, how would you go about doing so?

@anoduck if you are using the same config in this gist, you don't have to add it. The variable lsp_defaults.capabilities has that enabled.

https://gist.github.com/VonHeikemen/8fc2aa6da030757a5612393d0ae060bd#file-init-lua-L97-L104

@VonHeikemen Awesome sauce! Thanks! What I needed to know.

I am really grateful for your guides on creating a configuration for nvim in lua. They are really detailed, and exceptionally worded. I find myself going back to them for reference, and now that I found you keep them updated, I will be returning to them often. It is the best tutorial I have read.

You should write a book on it and get no-starch press to publish it. You could title it, something like, "Absolute Nvim, in lua" ... just a suggestion... :)