refactor: create function for deferred loading

The benefit of this is that users only pay for what they use. If e.g.
only `vim.lsp.buf_get_clients()` is called then they don't need to load
all modules under `vim.lsp` which could lead to significant startuptime
saving.

Also `vim.lsp.module` is a bit nicer to user compared to
`require("vim.lsp.module")`.

This isn't used for some nested modules such as `filetype` as it breaks
tests with error messages such as "attempt to index field 'detect'".
It's not entirely certain the reason for this, but it is likely it is
due to filetype being precompiled which would imply deferred loading
isn't needed for performance reasons.

runtime/lua/vim/lsp/_completion.lua

@@ -8,7 +8,7 @@ local ms = protocol.Methods
 ---@return string parsed snippet
 local function parse_snippet(input)
   local ok, parsed = pcall(function()
-    return require('vim.lsp._snippet_grammar').parse(input)
+    return vim.lsp._snippet_grammar.parse(input)
   end)
   return ok and tostring(parsed) or input
 end
@@ -206,7 +206,7 @@ function M.omnifunc(findstart, base)
     local params = util.make_position_params(win, client.offset_encoding)
     client.request(ms.textDocument_completion, params, function(err, result)
       if err then
-        require('vim.lsp.log').warn(err.message)
+        vim.lsp.log.warn(err.message)
       end
       if result and vim.fn.mode() == 'i' then
         local matches

runtime/lua/vim/lsp/_dynamic.lua

@@ -1,4 +1,4 @@
-local glob = require('vim.glob')
+local glob = vim.glob
 
 --- @class lsp.DynamicCapabilities
 --- @field capabilities table<string, lsp.Registration[]>

runtime/lua/vim/lsp/_watchfiles.lua

@@ -1,6 +1,6 @@
 local bit = require('bit')
-local glob = require('vim.glob')
-local watch = require('vim._watch')
+local glob = vim.glob
+local watch = vim._watch
 local protocol = require('vim.lsp.protocol')
 local ms = protocol.Methods
 local lpeg = vim.lpeg

runtime/lua/vim/lsp/diagnostic.lua

@@ -1,8 +1,6 @@
 ---@brief lsp-diagnostic
 
-local util = require('vim.lsp.util')
 local protocol = require('vim.lsp.protocol')
-local log = require('vim.lsp.log')
 local ms = protocol.Methods
 
 local api = vim.api
@@ -95,7 +93,7 @@ local function tags_lsp_to_vim(diagnostic, client_id)
       tags = tags or {}
       tags.deprecated = true
     else
-      log.info(string.format('Unknown DiagnosticTag %d from LSP client %d', tag, client_id))
+      vim.lsp.log.info(string.format('Unknown DiagnosticTag %d from LSP client %d', tag, client_id))
     end
   end
   return tags
@@ -425,7 +423,7 @@ end
 local function _refresh(bufnr, opts)
   opts = opts or {}
   opts['bufnr'] = bufnr
-  util._refresh(ms.textDocument_diagnostic, opts)
+  vim.lsp.util._refresh(ms.textDocument_diagnostic, opts)
 end
 
 --- Enable pull diagnostics for a buffer

runtime/lua/vim/lsp/handlers.lua

@@ -120,7 +120,7 @@ M[ms.client_registerCapability] = function(_, result, ctx)
   local unsupported = {}
   for _, reg in ipairs(result.registrations) do
     if reg.method == ms.workspace_didChangeWatchedFiles then
-      require('vim.lsp._watchfiles').register(reg, ctx)
+      vim.lsp._watchfiles.register(reg, ctx)
     elseif not client.dynamic_capabilities:supports_registration(reg.method) then
       unsupported[#unsupported + 1] = reg.method
     end
@@ -144,7 +144,7 @@ M[ms.client_unregisterCapability] = function(_, result, ctx)
 
   for _, unreg in ipairs(result.unregisterations) do
     if unreg.method == ms.workspace_didChangeWatchedFiles then
-      require('vim.lsp._watchfiles').unregister(unreg, ctx)
+      vim.lsp._watchfiles.unregister(unreg, ctx)
     end
   end
   return vim.NIL
@@ -223,19 +223,19 @@ M[ms.workspace_workspaceFolders] = function(_, _, ctx)
 end
 
 M[ms.textDocument_publishDiagnostics] = function(...)
-  return require('vim.lsp.diagnostic').on_publish_diagnostics(...)
+  return vim.lsp.diagnostic.on_publish_diagnostics(...)
 end
 
 M[ms.textDocument_diagnostic] = function(...)
-  return require('vim.lsp.diagnostic').on_diagnostic(...)
+  return vim.lsp.diagnostic.on_diagnostic(...)
 end
 
 M[ms.textDocument_codeLens] = function(...)
-  return require('vim.lsp.codelens').on_codelens(...)
+  return vim.lsp.codelens.on_codelens(...)
 end
 
 M[ms.textDocument_inlayHint] = function(...)
-  return require('vim.lsp.inlay_hint').on_inlayhint(...)
+  return vim.lsp.inlay_hint.on_inlayhint(...)
 end
 
 --see: https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_references
@@ -643,7 +643,7 @@ end
 
 ---@see https://microsoft.github.io/language-server-protocol/specification/#workspace_inlayHint_refresh
 M[ms.workspace_inlayHint_refresh] = function(err, result, ctx, config)
-  return require('vim.lsp.inlay_hint').on_refresh(err, result, ctx, config)
+  return vim.lsp.inlay_hint.on_refresh(err, result, ctx, config)
 end
 
 -- Add boilerplate error validation and logging for all of these.

runtime/lua/vim/lsp/health.lua

@@ -5,7 +5,7 @@ function M.check()
   local report_info = vim.health.info
   local report_warn = vim.health.warn
 
-  local log = require('vim.lsp.log')
+  local log = vim.lsp.log
   local current_log_level = log.get_level()
   local log_level_string = log.levels[current_log_level]
   report_info(string.format('LSP log level : %s', log_level_string))

runtime/lua/vim/lsp/util.lua

@@ -3,7 +3,7 @@ local snippet = require('vim.lsp._snippet_grammar')
 local validate = vim.validate
 local api = vim.api
 local list_extend = vim.list_extend
-local highlight = require('vim.highlight')
+local highlight = vim.highlight
 local uv = vim.uv
 
 local npcall = vim.F.npcall
@@ -636,7 +636,7 @@ end
 ---@see complete-items
 function M.text_document_completion_list_to_complete_items(result, prefix)
   vim.deprecate('vim.lsp.util.text_document_completion_list_to_complete_items()', nil, '0.11')
-  return require('vim.lsp._completion')._lsp_to_complete_items(result, prefix)
+  return vim.lsp._completion._lsp_to_complete_items(result, prefix)
 end
 
 --- Like vim.fn.bufwinid except it works across tabpages.