feat(lua): low-level interpreter mode (nvim -ll)

runtime/doc/starting.txt

@@ -239,6 +239,14 @@ argument.
 		Disables |shada| unless |-i| was given.
 		Disables swapfile (like |-n|).
 
+							*-ll*
+-ll {script} [args]
+		Execute a lua script, similarly to |-l|, but the editor is not
+		initialized. This gives a lua enviroment similar to a worker
+		thread. See |lua-loop-threading|.
+
+		Unlike `-l` no prior arguments are allowed.
+
 							*-b*
 -b		Binary mode.  File I/O will only recognize <NL> to separate
 		lines.  The 'expandtab' option will be reset.  The 'textwidth'

runtime/lua/vim/_init_packages.lua

@@ -42,8 +42,11 @@ function vim._load_package(name)
   return nil
 end
 
--- Insert vim._load_package after the preloader at position 2
-table.insert(package.loaders, 2, vim._load_package)
+-- TODO(bfredl): dedicated state for this?
+if vim.api then
+  -- Insert vim._load_package after the preloader at position 2
+  table.insert(package.loaders, 2, vim._load_package)
+end
 
 -- builtin functions which always should be available
 require('vim.shared')
@@ -78,6 +81,6 @@ function vim.empty_dict()
 end
 
 -- only on main thread: functions for interacting with editor state
-if not vim.is_thread() then
+if vim.api and not vim.is_thread() then
   require('vim._editor')
 end

src/nvim/lua/executor.c

@@ -64,6 +64,7 @@
 #include "nvim/window.h"
 
 static int in_fast_callback = 0;
+static bool in_script = false;
 
 // Initialized in nlua_init().
 static lua_State *global_lstate = NULL;
@@ -133,8 +134,13 @@ static void nlua_error(lua_State *const lstate, const char *const msg)
     str = lua_tolstring(lstate, -1, &len);
   }
 
-  msg_ext_set_kind("lua_error");
-  semsg_multiline(msg, (int)len, str);
+  if (in_script) {
+    os_errmsg(str);
+    os_errmsg("\n");
+  } else {
+    msg_ext_set_kind("lua_error");
+    semsg_multiline(msg, (int)len, str);
+  }
 
   lua_pop(lstate, 1);
 }
@@ -534,7 +540,7 @@ int nlua_get_global_ref_count(void)
   return nlua_global_refs->ref_count;
 }
 
-static void nlua_common_vim_init(lua_State *lstate, bool is_thread)
+static void nlua_common_vim_init(lua_State *lstate, bool is_thread, bool is_standalone)
   FUNC_ATTR_NONNULL_ARG(1)
 {
   nlua_ref_state_t *ref_state = nlua_new_ref_state(lstate, is_thread);
@@ -567,7 +573,9 @@ static void nlua_common_vim_init(lua_State *lstate, bool is_thread)
   lua_setfield(lstate, -2, "_empty_dict_mt");
 
   // vim.loop
-  if (is_thread) {
+  if (is_standalone) {
+    // do nothing, use libluv like in a standalone interpreter
+  } else if (is_thread) {
     luv_set_callback(lstate, nlua_luv_thread_cb_cfpcall);
     luv_set_thread(lstate, nlua_luv_thread_cfpcall);
     luv_set_cthread(lstate, nlua_luv_thread_cfcpcall);
@@ -606,7 +614,7 @@ static int nlua_module_preloader(lua_State *lstate)
   return 1;
 }
 
-static bool nlua_init_packages(lua_State *lstate)
+static bool nlua_init_packages(lua_State *lstate, bool is_standalone)
   FUNC_ATTR_NONNULL_ALL
 {
   // put builtin packages in preload
@@ -618,7 +626,7 @@ static bool nlua_init_packages(lua_State *lstate)
     lua_pushcclosure(lstate, nlua_module_preloader, 1);  // [package, preload, cclosure]
     lua_setfield(lstate, -2, def.name);  // [package, preload]
 
-    if (nlua_disable_preload && strequal(def.name, "vim.inspect")) {
+    if ((nlua_disable_preload && !is_standalone) && strequal(def.name, "vim.inspect")) {
       break;
     }
   }
@@ -769,7 +777,7 @@ static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_pushcfunction(lstate, &nlua_ui_detach);
   lua_setfield(lstate, -2, "ui_detach");
 
-  nlua_common_vim_init(lstate, false);
+  nlua_common_vim_init(lstate, false, false);
 
   // patch require() (only for --startuptime)
   if (time_fd != NULL) {
@@ -788,7 +796,7 @@ static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 
   lua_setglobal(lstate, "vim");
 
-  if (!nlua_init_packages(lstate)) {
+  if (!nlua_init_packages(lstate, false)) {
     return false;
   }
 
@@ -823,10 +831,29 @@ void nlua_init(char **argv, int argc, int lua_arg0)
 }
 
 static lua_State *nlua_thread_acquire_vm(void)
+{
+  return nlua_init_state(true);
+}
+
+void nlua_run_script(char **argv, int argc, int lua_arg0)
+  FUNC_ATTR_NORETURN
+{
+  in_script = true;
+  global_lstate = nlua_init_state(false);
+  luv_set_thread_cb(nlua_thread_acquire_vm, nlua_common_free_all_mem);
+  nlua_init_argv(global_lstate, argv, argc, lua_arg0);
+  bool lua_ok = nlua_exec_file(argv[lua_arg0 - 1]);
+#ifdef EXITFREE
+  nlua_free_all_mem();
+#endif
+  exit(lua_ok ? 0 : 1);
+}
+
+lua_State *nlua_init_state(bool thread)
 {
   // If it is called from the main thread, it will attempt to rebuild the cache.
   const uv_thread_t self = uv_thread_self();
-  if (uv_thread_equal(&main_thread, &self)) {
+  if (!in_script && uv_thread_equal(&main_thread, &self)) {
     runtime_search_path_validate();
   }
 
@@ -835,9 +862,11 @@ static lua_State *nlua_thread_acquire_vm(void)
   // Add in the lua standard libraries
   luaL_openlibs(lstate);
 
-  // print
-  lua_pushcfunction(lstate, &nlua_print);
-  lua_setglobal(lstate, "print");
+  if (!in_script) {
+    // print
+    lua_pushcfunction(lstate, &nlua_print);
+    lua_setglobal(lstate, "print");
+  }
 
   lua_pushinteger(lstate, 0);
   lua_setfield(lstate, LUA_REGISTRYINDEX, "nlua.refcount");
@@ -845,18 +874,20 @@ static lua_State *nlua_thread_acquire_vm(void)
   // vim
   lua_newtable(lstate);
 
-  nlua_common_vim_init(lstate, true);
+  nlua_common_vim_init(lstate, thread, in_script);
 
   nlua_state_add_stdlib(lstate, true);
 
-  lua_createtable(lstate, 0, 0);
-  lua_pushcfunction(lstate, nlua_thr_api_nvim__get_runtime);
-  lua_setfield(lstate, -2, "nvim__get_runtime");
-  lua_setfield(lstate, -2, "api");
+  if (!in_script) {
+    lua_createtable(lstate, 0, 0);
+    lua_pushcfunction(lstate, nlua_thr_api_nvim__get_runtime);
+    lua_setfield(lstate, -2, "nvim__get_runtime");
+    lua_setfield(lstate, -2, "api");
+  }
 
   lua_setglobal(lstate, "vim");
 
-  nlua_init_packages(lstate);
+  nlua_init_packages(lstate, in_script);
 
   lua_getglobal(lstate, "package");
   lua_getfield(lstate, -1, "loaded");

src/nvim/main.c

@@ -239,6 +239,14 @@ int main(int argc, char **argv)
 
   argv0 = argv[0];
 
+  if (argc > 1 && STRICMP(argv[1], "-ll") == 0) {
+    if (argc == 2) {
+      print_mainerr(err_arg_missing, argv[1]);
+      exit(1);
+    }
+    nlua_run_script(argv, argc, 3);
+  }
+
   char *fname = NULL;     // file name from command line
   mparm_T params;         // various parameters passed between
                           // main() and other functions.
@@ -2110,6 +2118,12 @@ static int execute_env(char *env)
 /// @param str     string to append to the primary error message, or NULL
 static void mainerr(const char *errstr, const char *str)
   FUNC_ATTR_NORETURN
+{
+  print_mainerr(errstr, str);
+  os_exit(1);
+}
+
+static void print_mainerr(const char *errstr, const char *str)
 {
   char *prgname = path_tail(argv0);
 
@@ -2126,8 +2140,6 @@ static void mainerr(const char *errstr, const char *str)
   os_errmsg(_("\nMore info with \""));
   os_errmsg(prgname);
   os_errmsg(" -h\"\n");
-
-  os_exit(1);
 }
 
 /// Prints version information for "nvim -v" or "nvim --version".