vim: refactor LSP configuration

config/nvim/lua/user/plugins/lsp.lua

@@ -1,10 +1,38 @@
-local filetypes = {
+local custom_server_opts = {
+  omnisharp = {
+    -- Support for showing unimported types and adding `using` directives.
+    enable_import_completion = true,
+
+    -- Don't include preview versions of the .NET SDK.
+    sdk_include_prereleases = false,
+  },
+
+  lua_ls = {
+    settings = {
+      Lua = {
+        -- I'm using lua only inside neovim, so the runtime is LuaJIT.
+        runtime = { version = 'LuaJIT' },
+
+        -- Get the language server to recognize the `vim` global.
+        diagnostics = { globals = {'vim'} },
+
+        -- Make the server aware of Neovim runtime files.
+        workspace = { library = vim.api.nvim_get_runtime_file("", true) },
+
+        -- Do not send telemetry data containing a randomized but unique identifier
+        telemetry = { enable = false },
+      },
+    },
+  }
+}
+
+local custom_filetype_attach = {
   cs = function(client, bufnr)
     client.server_capabilities.semanticTokensProvider = nil
   end,
 }
 
-local on_attach = function(client, bufnr)
+local custom_attach = function(client, bufnr)
   vim.bo.omnifunc = 'v:lua.vim.lsp.omnifunc'  -- do completion with <c-x><c-o>
 
   local map = vim.keymap.set
@@ -19,62 +47,36 @@ local on_attach = function(client, bufnr)
   map('n', 'grr',         vim.lsp.buf.rename,                     opts)
   map('n', 'gt',          vim.lsp.buf.type_definition,            opts)
 
-  local filetype_attach = filetypes[vim.bo.filetype]
+  local filetype_attach = custom_filetype_attach[vim.bo.filetype]
   if filetype_attach then filetype_attach(client, bufnr) end
 end
 
-local config = function()
+local custom_capabilities = function()
   local capabilities = vim.lsp.protocol.make_client_capabilities()
-  local has_cmp, cmp = pcall(require, 'cmp_nvim_lsp')
-  if has_cmp then
+
+  local ok, cmp = pcall(require, 'cmp_nvim_lsp')
+  if ok then
     vim.tbl_deep_extend('force', capabilities, cmp.default_capabilities())
   end
 
+  return capabilities
+end
+
+local config = function()
   local lsp = require 'lspconfig'
+  local capabilities = custom_capabilities()
+
   require('mason').setup()
   require('mason-lspconfig').setup {
     handlers = {
-      -- default handler
       function(server)
-        require('lspconfig')[server].setup {
-          on_attach = on_attach,
+        local common_opts = {
+          on_attach = custom_attach,
           capabilities = capabilities,
         }
-      end,
-
-      omnisharp = function()
-        lsp.omnisharp.setup {
-          on_attach = on_attach,
-          capabilities = capabilities,
-
-          -- Support for showing unimported types and adding `using` directives.
-          enable_import_completion = true,
-
-          -- Don't include preview versions of the .NET SDK.
-          sdk_include_prereleases = false,
-        }
-      end,
-
-      lua_ls = function()
-        lsp.lua_ls.setup {
-          on_attach = on_attach,
-          capabilities = capabilities,
-          settings = {
-            Lua = {
-              -- I'm using lua only inside neovim, so the runtime is LuaJIT.
-              runtime = { version = 'LuaJIT' },
-
-              -- Get the language server to recognize the `vim` global.
-              diagnostics = { globals = {'vim'} },
-
-              -- Make the server aware of Neovim runtime files.
-              workspace = { library = vim.api.nvim_get_runtime_file("", true) },
-
-              -- Do not send telemetry data containing a randomized but unique identifier
-              telemetry = { enable = false },
-            },
-          },
-        }
+        local server_opts = custom_server_opts[server] or {}
+        local opts = vim.tbl_extend('force', common_opts, server_opts)
+        lsp[server].setup(opts)
       end,
     }
   }