spacevim/bundle/nvim-lspconfig/lua/lspconfig/server_configurations/dartls.lua

local util = require 'lspconfig.util'

local bin_name = 'dart'

local find_dart_sdk_root_path = function()
  if os.getenv 'FLUTTER_SDK' then
    local flutter_path = os.getenv 'FLUTTER_SDK'
    return util.path.join(flutter_path, 'cache', 'dart-sdk', 'bin', 'dart')
  elseif vim.fn['executable'] 'flutter' == 1 then
    local flutter_path = vim.fn['resolve'](vim.fn['exepath'] 'flutter')
    local flutter_bin = vim.fn['fnamemodify'](flutter_path, ':h')
    return util.path.join(flutter_bin, 'cache', 'dart-sdk', 'bin', 'dart')
  elseif vim.fn['executable'] 'dart' == 1 then
    return vim.fn['resolve'](vim.fn['exepath'] 'dart')
  else
    return ''
  end
end

local analysis_server_snapshot_path = function()
  local dart_sdk_root_path = vim.fn['fnamemodify'](find_dart_sdk_root_path(), ':h')
  local snapshot = util.path.join(dart_sdk_root_path, 'snapshots', 'analysis_server.dart.snapshot')

  if vim.fn['has'] 'win32' == 1 or vim.fn['has'] 'win64' == 1 then
    snapshot = snapshot:gsub('/', '\\')
  end

  return snapshot
end

return {
  default_config = {
    cmd = { bin_name, analysis_server_snapshot_path(), '--lsp' },
    filetypes = { 'dart' },
    root_dir = util.root_pattern 'pubspec.yaml',
    init_options = {
      onlyAnalyzeProjectsWithOpenFiles = true,
      suggestFromUnimportedLibraries = true,
      closingLabels = true,
      outline = true,
      flutterOutline = true,
    },
    settings = {
      dart = {
        completeFunctionCalls = true,
        showTodos = true,
      },
    },
  },
  docs = {
    package_json = 'https://raw.githubusercontent.com/Dart-Code/Dart-Code/master/package.json',
    description = [[
https://github.com/dart-lang/sdk/tree/master/pkg/analysis_server/tool/lsp_spec

Language server for dart.
]],
    default_config = {
      root_dir = [[root_pattern("pubspec.yaml")]],
    },
  },
}