feat(api): add `nvim_cmd`

Adds the API function `nvim_cmd` which allows executing an Ex-command through a Dictionary which can have the same values as the return value of `nvim_parse_cmd()`. This makes it much easier to do things like passing arguments with a space to commands that otherwise may not allow it, or to make commands interpret certain characters literally when they otherwise would not.

8 files changed, 949 insertions, 126 deletions

diff --git a/src/nvim/api/keysets.lua b/src/nvim/api/keysets.lua
index 5baffaf505..78f8ed3cca 100644
--- a/src/nvim/api/keysets.lua
+++ b/src/nvim/api/keysets.lua
@@ -155,5 +155,44 @@ return {
   create_augroup = {
     "clear";
   };
+  cmd = {
+    "cmd";
+    "range";
+    "count";
+    "reg";
+    "bang";
+    "args";
+    "magic";
+    "mods";
+    "nargs";
+    "addr";
+    "nextcmd";
+  };
+  cmd_magic = {
+    "file";
+    "bar";
+  };
+  cmd_mods = {
+    "silent";
+    "emsg_silent";
+    "sandbox";
+    "noautocmd";
+    "browse";
+    "confirm";
+    "hide";
+    "keepalt";
+    "keepjumps";
+    "keepmarks";
+    "keeppatterns";
+    "lockmarks";
+    "noswapfile";
+    "tab";
+    "verbose";
+    "vertical";
+    "split";
+  };
+  cmd_opts = {
+    "output";
+  };
 }
 
diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index a2ee4f91bc..725033a4c5 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -19,6 +19,7 @@
 #include "nvim/decoration.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
+#include "nvim/ex_cmds_defs.h"
 #include "nvim/extmark.h"
 #include "nvim/fileio.h"
 #include "nvim/getchar.h"
@@ -1691,3 +1692,174 @@ int init_sign_text(char **sign_text, char *text)
 
   return OK;
 }
+
+/// Check if a string contains only whitespace characters.
+bool string_iswhite(String str)
+{
+  for (size_t i = 0; i < str.size; i++) {
+    if (!ascii_iswhite(str.data[i])) {
+      // Found a non-whitespace character
+      return false;
+    } else if (str.data[i] == NUL) {
+      // Terminate at first occurence of a NUL character
+      break;
+    }
+  }
+  return true;
+}
+
+// Add modifier string for command into the command line. Includes trailing whitespace if non-empty.
+// @return OK or FAIL.
+static int add_cmd_modifier_str(char *cmdline, size_t *pos, const size_t bufsize,
+                                CmdParseInfo *cmdinfo)
+{
+#define APPEND_MODIFIER(...) \
+  do { \
+    if (*pos < bufsize) { \
+      *pos += (size_t)snprintf(cmdline + *pos, bufsize - *pos, __VA_ARGS__); \
+    } \
+    if (*pos < bufsize) { \
+      cmdline[*pos] = ' '; \
+      *pos += 1; \
+    } else { \
+      goto err; \
+    } \
+  } while (0)
+
+#define APPEND_MODIFIER_IF(cond, mod) \
+  do { \
+    if (cond) { \
+      APPEND_MODIFIER(mod); \
+    } \
+  } while (0)
+
+  if (cmdinfo->cmdmod.tab != 0) {
+    APPEND_MODIFIER("%dtab", cmdinfo->cmdmod.tab - 1);
+  }
+  if (cmdinfo->verbose != -1) {
+    APPEND_MODIFIER("%ldverbose", cmdinfo->verbose);
+  }
+
+  switch (cmdinfo->cmdmod.split & (WSP_ABOVE | WSP_BELOW | WSP_TOP | WSP_BOT)) {
+  case WSP_ABOVE:
+    APPEND_MODIFIER("aboveleft");
+    break;
+  case WSP_BELOW:
+    APPEND_MODIFIER("belowright");
+    break;
+  case WSP_TOP:
+    APPEND_MODIFIER("topleft");
+    break;
+  case WSP_BOT:
+    APPEND_MODIFIER("botright");
+    break;
+  default:
+    break;
+  }
+
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.split & WSP_VERT, "vertical");
+
+  if (cmdinfo->emsg_silent) {
+    APPEND_MODIFIER("silent!");
+  } else if (cmdinfo->silent) {
+    APPEND_MODIFIER("silent");
+  }
+
+  APPEND_MODIFIER_IF(cmdinfo->sandbox, "sandbox");
+  APPEND_MODIFIER_IF(cmdinfo->noautocmd, "noautocmd");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.browse, "browse");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.confirm, "confirm");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.hide, "hide");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.keepalt, "keepalt");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.keepjumps, "keepjumps");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.keepmarks, "keepmarks");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.keeppatterns, "keeppatterns");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.lockmarks, "lockmarks");
+  APPEND_MODIFIER_IF(cmdinfo->cmdmod.noswapfile, "noswapfile");
+
+  return OK;
+err:
+  return FAIL;
+
+#undef APPEND_MODIFIER
+#undef APPEND_MODIFIER_IF
+}
+
+/// Build cmdline string for command, used by `nvim_cmd()`.
+///
+/// @return OK or FAIL.
+int build_cmdline_str(char **cmdlinep, exarg_T *eap, CmdParseInfo *cmdinfo, char **args,
+                      size_t argc)
+{
+  const size_t bufsize = IOSIZE;
+  size_t pos = 0;
+  char *cmdline = xcalloc(bufsize, sizeof(char));
+
+#define CMDLINE_APPEND(...) \
+  do { \
+    if (pos < bufsize) { \
+      pos += (size_t)snprintf(cmdline + pos, bufsize - pos, __VA_ARGS__); \
+    } else { \
+      goto err; \
+    } \
+  } while (0)
+
+  // Command modifiers.
+  if (add_cmd_modifier_str(cmdline, &pos, bufsize, cmdinfo) == FAIL) {
+    goto err;
+  }
+
+  // Command range / count.
+  if (eap->argt & EX_RANGE) {
+    if (eap->addr_count == 1) {
+      CMDLINE_APPEND("%ld", eap->line2);
+    } else if (eap->addr_count > 1) {
+      CMDLINE_APPEND("%ld,%ld", eap->line1, eap->line2);
+      eap->addr_count = 2;  // Make sure address count is not greater than 2
+    }
+  }
+
+  // Keep the index of the position where command name starts, so eap->cmd can point to it.
+  size_t cmdname_idx = pos;
+  CMDLINE_APPEND("%s", eap->cmd);
+  eap->cmd = cmdline + cmdname_idx;
+
+  // Command bang.
+  if (eap->argt & EX_BANG && eap->forceit) {
+    CMDLINE_APPEND("!");
+  }
+
+  // Command register.
+  if (eap->argt & EX_REGSTR && eap->regname) {
+    CMDLINE_APPEND(" %c", eap->regname);
+  }
+
+  // Iterate through each argument and store the starting position and length of each argument in
+  // the cmdline string in `eap->args` and `eap->arglens`, respectively.
+  eap->args = xcalloc(argc, sizeof(char *));
+  eap->arglens = xcalloc(argc, sizeof(size_t));
+  for (size_t i = 0; i < argc; i++) {
+    eap->args[i] = cmdline + pos + 1;  // add 1 to skip the leading space.
+    eap->arglens[i] = STRLEN(args[i]);
+    CMDLINE_APPEND(" %s", args[i]);
+  }
+  eap->argc = argc;
+  eap->arg = argc > 0 ? eap->args[0] : NULL;
+
+  // Replace, :make and :grep with 'makeprg' and 'grepprg'.
+  char *p = replace_makeprg(eap, eap->arg, cmdlinep);
+  if (p != eap->arg) {
+    // If replace_makeprg modified the cmdline string, correct the argument pointers.
+    assert(argc == 1);
+    eap->arg = p;
+    eap->args[0] = p;
+  }
+
+  *cmdlinep = cmdline;
+  return OK;
+err:
+  xfree(cmdline);
+  return FAIL;
+
+#undef CMDLINE_APPEND
+}
diff --git a/src/nvim/api/vimscript.c b/src/nvim/api/vimscript.c
index c4a301839f..02f406d686 100644
--- a/src/nvim/api/vimscript.c
+++ b/src/nvim/api/vimscript.c
@@ -10,10 +10,14 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/api/vimscript.h"
 #include "nvim/ascii.h"
+#include "nvim/autocmd.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
 #include "nvim/eval/userfunc.h"
 #include "nvim/ex_cmds2.h"
+#include "nvim/ops.h"
+#include "nvim/strings.h"
+#include "nvim/vim.h"
 #include "nvim/viml/parser/expressions.h"
 #include "nvim/viml/parser/parser.h"
 #include "nvim/window.h"
@@ -22,7 +26,9 @@
 # include "api/vimscript.c.generated.h"
 #endif
 
-/// Executes Vimscript (multiline block of Ex-commands), like anonymous
+#define IS_USER_CMDIDX(idx) ((int)(idx) < 0)
+
+/// Executes Vimscript (multiline block of Ex commands), like anonymous
 /// |:source|.
 ///
 /// Unlike |nvim_command()| this function supports heredocs, script-scope (s:),
@@ -32,6 +38,7 @@
 ///
 /// @see |execute()|
 /// @see |nvim_command()|
+/// @see |nvim_cmd()|
 ///
 /// @param src      Vimscript code
 /// @param output   Capture and return all (non-error, non-shell |:!|) output
@@ -89,13 +96,16 @@ theend:
   return (String)STRING_INIT;
 }
 
-/// Executes an ex-command.
+/// Executes an Ex command.
 ///
 /// On execution error: fails with VimL error, does not update v:errmsg.
 ///
-/// @see |nvim_exec()|
+/// Prefer using |nvim_cmd()| or |nvim_exec()| over this. To evaluate multiple lines of Vim script
+/// or an Ex command directly, use |nvim_exec()|. To construct an Ex command using a structured
+/// format and then execute it, use |nvim_cmd()|. To modify an Ex command before evaluating it, use
+/// |nvim_parse_cmd()| in conjunction with |nvim_cmd()|.
 ///
-/// @param command  Ex-command string
+/// @param command  Ex command string
 /// @param[out] err Error details (Vim error), if any
 void nvim_command(String command, Error *err)
   FUNC_API_SINCE(1)
@@ -978,3 +988,370 @@ end:
   xfree(cmdline);
   return result;
 }
+
+/// Executes an Ex command.
+///
+/// Unlike |nvim_command()| this command takes a structured Dictionary instead of a String. This
+/// allows for easier construction and manipulation of an Ex command. This also allows for things
+/// such as having spaces inside a command argument, expanding filenames in a command that otherwise
+/// doesn't expand filenames, etc.
+///
+/// @see |nvim_exec()|
+/// @see |nvim_command()|
+///
+/// @param cmd       Command to execute. Must be a Dictionary that can contain the same values as
+///                  the return value of |nvim_parse_cmd()| except "addr", "nargs" and "nextcmd"
+///                  which are ignored if provided. All values except for "cmd" are optional.
+/// @param opts      Optional parameters.
+///                  - output: (boolean, default false) Whether to return command output.
+/// @param[out] err  Error details, if any.
+/// @return Command output (non-error, non-shell |:!|) if `output` is true, else empty string.
+String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error *err)
+  FUNC_API_SINCE(10)
+{
+  exarg_T ea;
+  memset(&ea, 0, sizeof(ea));
+  ea.verbose_save = -1;
+  ea.save_msg_silent = -1;
+
+  CmdParseInfo cmdinfo;
+  memset(&cmdinfo, 0, sizeof(cmdinfo));
+  cmdinfo.verbose = -1;
+
+  char *cmdline = NULL;
+  char *cmdname = NULL;
+  char **args = NULL;
+  size_t argc = 0;
+
+  String retv = (String)STRING_INIT;
+
+#define OBJ_TO_BOOL(var, value, default, varname) \
+  do { \
+    var = api_object_to_bool(value, varname, default, err); \
+    if (ERROR_SET(err)) { \
+      goto end; \
+    } \
+  } while (0)
+
+#define VALIDATION_ERROR(...) \
+  do { \
+    api_set_error(err, kErrorTypeValidation, __VA_ARGS__); \
+    goto end; \
+  } while (0)
+
+  bool output;
+  OBJ_TO_BOOL(output, opts->output, false, "'output'");
+
+  // First, parse the command name and check if it exists and is valid.
+  if (!HAS_KEY(cmd->cmd) || cmd->cmd.type != kObjectTypeString
+      || cmd->cmd.data.string.data[0] == NUL) {
+    VALIDATION_ERROR("'cmd' must be a non-empty String");
+  }
+
+  cmdname = string_to_cstr(cmd->cmd.data.string);
+  ea.cmd = cmdname;
+
+  char *p = find_ex_command(&ea, NULL);
+
+  // If this looks like an undefined user command and there are CmdUndefined
+  // autocommands defined, trigger the matching autocommands.
+  if (p != NULL && ea.cmdidx == CMD_SIZE && ASCII_ISUPPER(*ea.cmd)
+      && has_event(EVENT_CMDUNDEFINED)) {
+    p = xstrdup(cmdname);
+    int ret = apply_autocmds(EVENT_CMDUNDEFINED, (char_u *)p, (char_u *)p, true, NULL);
+    xfree(p);
+    // If the autocommands did something and didn't cause an error, try
+    // finding the command again.
+    p = (ret && !aborting()) ? find_ex_command(&ea, NULL) : ea.cmd;
+  }
+
+  if (p == NULL || ea.cmdidx == CMD_SIZE) {
+    VALIDATION_ERROR("Command not found: %s", cmdname);
+  }
+  if (is_cmd_ni(ea.cmdidx)) {
+    VALIDATION_ERROR("Command not implemented: %s", cmdname);
+  }
+
+  // Get the command flags so that we can know what type of arguments the command uses.
+  // Not required for a user command since `find_ex_command` already deals with it in that case.
+  if (!IS_USER_CMDIDX(ea.cmdidx)) {
+    ea.argt = get_cmd_argt(ea.cmdidx);
+  }
+
+  // Parse command arguments since it's needed to get the command address type.
+  if (HAS_KEY(cmd->args)) {
+    if (cmd->args.type != kObjectTypeArray) {
+      VALIDATION_ERROR("'args' must be an Array");
+    }
+    // Check if every argument is valid
+    for (size_t i = 0; i < cmd->args.data.array.size; i++) {
+      Object elem = cmd->args.data.array.items[i];
+      if (elem.type != kObjectTypeString) {
+        VALIDATION_ERROR("Command argument must be a String");
+      } else if (string_iswhite(elem.data.string)) {
+        VALIDATION_ERROR("Command argument must have non-whitespace characters");
+      }
+    }
+
+    argc = cmd->args.data.array.size;
+    bool argc_valid;
+
+    // Check if correct number of arguments is used.
+    switch (ea.argt & (EX_EXTRA | EX_NOSPC | EX_NEEDARG)) {
+    case EX_EXTRA | EX_NOSPC | EX_NEEDARG:
+      argc_valid = argc == 1;
+      break;
+    case EX_EXTRA | EX_NOSPC:
+      argc_valid = argc <= 1;
+      break;
+    case EX_EXTRA | EX_NEEDARG:
+      argc_valid = argc >= 1;
+      break;
+    case EX_EXTRA:
+      argc_valid = true;
+      break;
+    default:
+      argc_valid = argc == 0;
+      break;
+    }
+
+    if (!argc_valid) {
+      argc = 0;  // Ensure that args array isn't erroneously freed at the end.
+      VALIDATION_ERROR("Incorrect number of arguments supplied");
+    }
+
+    if (argc != 0) {
+      args = xcalloc(argc, sizeof(char *));
+
+      for (size_t i = 0; i < argc; i++) {
+        args[i] = string_to_cstr(cmd->args.data.array.items[i].data.string);
+      }
+    }
+  }
+
+  // Simply pass the first argument (if it exists) as the arg pointer to `set_cmd_addr_type()`
+  // since it only ever checks the first argument.
+  set_cmd_addr_type(&ea, argc > 0 ? (char_u *)args[0] : NULL);
+
+  if (HAS_KEY(cmd->range)) {
+    if (!(ea.argt & EX_RANGE)) {
+      VALIDATION_ERROR("Command cannot accept a range");
+    } else if (cmd->range.type != kObjectTypeArray) {
+      VALIDATION_ERROR("'range' must be an Array");
+    } else if (cmd->range.data.array.size > 2) {
+      VALIDATION_ERROR("'range' cannot contain more than two elements");
+    }
+
+    Array range = cmd->range.data.array;
+    ea.addr_count = (int)range.size;
+
+    for (size_t i = 0; i < range.size; i++) {
+      Object elem = range.items[i];
+      if (elem.type != kObjectTypeInteger || elem.data.integer < 0) {
+        VALIDATION_ERROR("'range' element must be a non-negative Integer");
+      }
+    }
+
+    if (range.size > 0) {
+      ea.line1 = range.items[0].data.integer;
+      ea.line2 = range.items[range.size - 1].data.integer;
+    }
+
+    if (invalid_range(&ea) != NULL) {
+      VALIDATION_ERROR("Invalid range provided");
+    }
+  }
+  if (ea.addr_count == 0) {
+    if (ea.argt & EX_DFLALL) {
+      set_cmd_dflall_range(&ea);  // Default range for range=%
+    } else {
+      ea.line1 = ea.line2 = get_cmd_default_range(&ea);  // Default range.
+
+      if (ea.addr_type == ADDR_OTHER) {
+        // Default is 1, not cursor.
+        ea.line2 = 1;
+      }
+    }
+  }
+
+  if (HAS_KEY(cmd->count)) {
+    if (!(ea.argt & EX_COUNT)) {
+      VALIDATION_ERROR("Command cannot accept a count");
+    } else if (cmd->count.type != kObjectTypeInteger || cmd->count.data.integer < 0) {
+      VALIDATION_ERROR("'count' must be a non-negative Integer");
+    }
+    set_cmd_count(&ea, cmd->count.data.integer, true);
+  }
+
+  if (HAS_KEY(cmd->reg)) {
+    if (!(ea.argt & EX_REGSTR)) {
+      VALIDATION_ERROR("Command cannot accept a register");
+    } else if (cmd->reg.type != kObjectTypeString || cmd->reg.data.string.size != 1) {
+      VALIDATION_ERROR("'reg' must be a single character");
+    }
+    char regname = cmd->reg.data.string.data[0];
+    if (regname == '=') {
+      VALIDATION_ERROR("Cannot use register \"=");
+    } else if (!valid_yank_reg(regname, ea.cmdidx != CMD_put && !IS_USER_CMDIDX(ea.cmdidx))) {
+      VALIDATION_ERROR("Invalid register: \"%c", regname);
+    }
+    ea.regname = (uint8_t)regname;
+  }
+
+  OBJ_TO_BOOL(ea.forceit, cmd->bang, false, "'bang'");
+  if (ea.forceit && !(ea.argt & EX_BANG)) {
+    VALIDATION_ERROR("Command cannot accept a bang");
+  }
+
+  if (HAS_KEY(cmd->magic)) {
+    if (cmd->magic.type != kObjectTypeDictionary) {
+      VALIDATION_ERROR("'magic' must be a Dictionary");
+    }
+
+    Dict(cmd_magic) magic = { 0 };
+    if (!api_dict_to_keydict(&magic, KeyDict_cmd_magic_get_field,
+                             cmd->magic.data.dictionary, err)) {
+      goto end;
+    }
+
+    OBJ_TO_BOOL(cmdinfo.magic.file, magic.file, ea.argt & EX_XFILE, "'magic.file'");
+    OBJ_TO_BOOL(cmdinfo.magic.bar, magic.bar, ea.argt & EX_TRLBAR, "'magic.bar'");
+  } else {
+    cmdinfo.magic.file = ea.argt & EX_XFILE;
+    cmdinfo.magic.bar = ea.argt & EX_TRLBAR;
+  }
+
+  if (HAS_KEY(cmd->mods)) {
+    if (cmd->mods.type != kObjectTypeDictionary) {
+      VALIDATION_ERROR("'mods' must be a Dictionary");
+    }
+
+    Dict(cmd_mods) mods = { 0 };
+    if (!api_dict_to_keydict(&mods, KeyDict_cmd_mods_get_field, cmd->mods.data.dictionary, err)) {
+      goto end;
+    }
+
+    if (HAS_KEY(mods.tab)) {
+      if (mods.tab.type != kObjectTypeInteger || mods.tab.data.integer < 0) {
+        VALIDATION_ERROR("'mods.tab' must be a non-negative Integer");
+      }
+      cmdinfo.cmdmod.tab = (int)mods.tab.data.integer + 1;
+    }
+
+    if (HAS_KEY(mods.verbose)) {
+      if (mods.verbose.type != kObjectTypeInteger || mods.verbose.data.integer <= 0) {
+        VALIDATION_ERROR("'mods.verbose' must be a non-negative Integer");
+      }
+      cmdinfo.verbose = mods.verbose.data.integer;
+    }
+
+    bool vertical;
+    OBJ_TO_BOOL(vertical, mods.vertical, false, "'mods.vertical'");
+    cmdinfo.cmdmod.split |= (vertical ? WSP_VERT : 0);
+
+    if (HAS_KEY(mods.split)) {
+      if (mods.split.type != kObjectTypeString) {
+        VALIDATION_ERROR("'mods.split' must be a String");
+      }
+
+      if (STRCMP(mods.split.data.string.data, "aboveleft") == 0
+          || STRCMP(mods.split.data.string.data, "leftabove") == 0) {
+        cmdinfo.cmdmod.split |= WSP_ABOVE;
+      } else if (STRCMP(mods.split.data.string.data, "belowright") == 0
+                 || STRCMP(mods.split.data.string.data, "rightbelow") == 0) {
+        cmdinfo.cmdmod.split |= WSP_BELOW;
+      } else if (STRCMP(mods.split.data.string.data, "topleft") == 0) {
+        cmdinfo.cmdmod.split |= WSP_TOP;
+      } else if (STRCMP(mods.split.data.string.data, "botright") == 0) {
+        cmdinfo.cmdmod.split |= WSP_BOT;
+      } else {
+        VALIDATION_ERROR("Invalid value for 'mods.split'");
+      }
+    }
+
+    OBJ_TO_BOOL(cmdinfo.silent, mods.silent, false, "'mods.silent'");
+    OBJ_TO_BOOL(cmdinfo.emsg_silent, mods.emsg_silent, false, "'mods.emsg_silent'");
+    OBJ_TO_BOOL(cmdinfo.sandbox, mods.sandbox, false, "'mods.sandbox'");
+    OBJ_TO_BOOL(cmdinfo.noautocmd, mods.noautocmd, false, "'mods.noautocmd'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.browse, mods.browse, false, "'mods.browse'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.confirm, mods.confirm, false, "'mods.confirm'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.hide, mods.hide, false, "'mods.hide'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.keepalt, mods.keepalt, false, "'mods.keepalt'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.keepjumps, mods.keepjumps, false, "'mods.keepjumps'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.keepmarks, mods.keepmarks, false, "'mods.keepmarks'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.keeppatterns, mods.keeppatterns, false, "'mods.keeppatterns'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.lockmarks, mods.lockmarks, false, "'mods.lockmarks'");
+    OBJ_TO_BOOL(cmdinfo.cmdmod.noswapfile, mods.noswapfile, false, "'mods.noswapfile'");
+
+    if (cmdinfo.sandbox && !(ea.argt & EX_SBOXOK)) {
+      VALIDATION_ERROR("Command cannot be run in sandbox");
+    }
+  }
+
+  // Finally, build the command line string that will be stored inside ea.cmdlinep.
+  // This also sets the values of ea.cmd, ea.arg, ea.args and ea.arglens.
+  if (build_cmdline_str(&cmdline, &ea, &cmdinfo, args, argc) == FAIL) {
+    goto end;
+  }
+  ea.cmdlinep = &cmdline;
+
+  garray_T capture_local;
+  const int save_msg_silent = msg_silent;
+  garray_T * const save_capture_ga = capture_ga;
+
+  if (output) {
+    ga_init(&capture_local, 1, 80);
+    capture_ga = &capture_local;
+  }
+
+  try_start();
+  if (output) {
+    msg_silent++;
+  }
+
+  WITH_SCRIPT_CONTEXT(channel_id, {
+    execute_cmd(&ea, &cmdinfo);
+  });
+
+  if (output) {
+    capture_ga = save_capture_ga;
+    msg_silent = save_msg_silent;
+  }
+  try_end(err);
+
+  if (ERROR_SET(err)) {
+    goto clear_ga;
+  }
+
+  if (output && capture_local.ga_len > 1) {
+    retv = (String){
+      .data = capture_local.ga_data,
+      .size = (size_t)capture_local.ga_len,
+    };
+    // redir usually (except :echon) prepends a newline.
+    if (retv.data[0] == '\n') {
+      memmove(retv.data, retv.data + 1, retv.size - 1);
+      retv.data[retv.size - 1] = '\0';
+      retv.size = retv.size - 1;
+    }
+    goto end;
+  }
+clear_ga:
+  if (output) {
+    ga_clear(&capture_local);
+  }
+end:
+  xfree(cmdline);
+  xfree(cmdname);
+  xfree(ea.args);
+  xfree(ea.arglens);
+  for (size_t i = 0; i < argc; i++) {
+    xfree(args[i]);
+  }
+  xfree(args);
+
+  return retv;
+
+#undef OBJ_TO_BOOL
+#undef VALIDATION_ERROR
+}
diff --git a/src/nvim/ex_cmds_defs.h b/src/nvim/ex_cmds_defs.h
index e4c85fbc9b..396e6fa19f 100644
--- a/src/nvim/ex_cmds_defs.h
+++ b/src/nvim/ex_cmds_defs.h
@@ -175,6 +175,9 @@ enum {
 /// Arguments used for Ex commands.
 struct exarg {
   char *arg;                    ///< argument of the command
+  char **args;                  ///< starting position of command arguments
+  size_t *arglens;              ///< length of command arguments
+  size_t argc;                  ///< number of command arguments
   char *nextcmd;                ///< next command (NULL if none)
   char *cmd;                    ///< the name of the command (except for :make)
   char **cmdlinep;              ///< pointer to pointer of allocated cmdline
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 316006befd..b27971581c 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -1218,7 +1218,7 @@ static char *skip_colon_white(const char *p, bool skipleadingwhite)
 /// Set the addr type for command
 ///
 /// @param p pointer to character after command name in cmdline
-static void set_cmd_addr_type(exarg_T *eap, char_u *p)
+void set_cmd_addr_type(exarg_T *eap, char_u *p)
 {
   // ea.addr_type for user commands is set by find_ucmd
   if (IS_USER_CMDIDX(eap->cmdidx)) {
@@ -1239,8 +1239,48 @@ static void set_cmd_addr_type(exarg_T *eap, char_u *p)
   }
 }
 
+/// Get default range number for command based on its address type
+linenr_T get_cmd_default_range(exarg_T *eap)
+{
+  switch (eap->addr_type) {
+  case ADDR_LINES:
+  case ADDR_OTHER:
+    // Default is the cursor line number.  Avoid using an invalid
+    // line number though.
+    return MIN(curwin->w_cursor.lnum, curbuf->b_ml.ml_line_count);
+    break;
+  case ADDR_WINDOWS:
+    return CURRENT_WIN_NR;
+    break;
+  case ADDR_ARGUMENTS:
+    return MIN(curwin->w_arg_idx + 1, ARGCOUNT);
+    break;
+  case ADDR_LOADED_BUFFERS:
+  case ADDR_BUFFERS:
+    return curbuf->b_fnum;
+    break;
+  case ADDR_TABS:
+    return CURRENT_TAB_NR;
+    break;
+  case ADDR_TABS_RELATIVE:
+  case ADDR_UNSIGNED:
+    return 1;
+    break;
+  case ADDR_QUICKFIX:
+    return (linenr_T)qf_get_cur_idx(eap);
+    break;
+  case ADDR_QUICKFIX_VALID:
+    return qf_get_cur_valid_idx(eap);
+    break;
+  default:
+    return 0;
+    // Will give an error later if a range is found.
+    break;
+  }
+}
+
 /// Set default command range for -range=% based on the addr type of the command
-static void set_cmd_default_range(exarg_T *eap)
+void set_cmd_dflall_range(exarg_T *eap)
 {
   buf_T *buf;
 
@@ -1320,6 +1360,25 @@ static void parse_register(exarg_T *eap)
   }
 }
 
+// Change line1 and line2 of Ex command to use count
+void set_cmd_count(exarg_T *eap, long count, bool validate)
+{
+  if (eap->addr_type != ADDR_LINES) {  // e.g. :buffer 2, :sleep 3
+    eap->line2 = count;
+    if (eap->addr_count == 0) {
+      eap->addr_count = 1;
+    }
+  } else {
+    eap->line1 = eap->line2;
+    eap->line2 += count - 1;
+    eap->addr_count++;
+    // Be vi compatible: no error message for out of range.
+    if (validate && eap->line2 > curbuf->b_ml.ml_line_count) {
+      eap->line2 = curbuf->b_ml.ml_line_count;
+    }
+  }
+}
+
 static int parse_count(exarg_T *eap, char **errormsg, bool validate)
 {
   // Check for a count.  When accepting a EX_BUFNAME, don't use "123foo" as a
@@ -1338,25 +1397,19 @@ static int parse_count(exarg_T *eap, char **errormsg, bool validate)
       }
       return FAIL;
     }
-    if (eap->addr_type != ADDR_LINES) {  // e.g. :buffer 2, :sleep 3
-      eap->line2 = n;
-      if (eap->addr_count == 0) {
-        eap->addr_count = 1;
-      }
-    } else {
-      eap->line1 = eap->line2;
-      eap->line2 += n - 1;
-      eap->addr_count++;
-      // Be vi compatible: no error message for out of range.
-      if (validate && eap->line2 > curbuf->b_ml.ml_line_count) {
-        eap->line2 = curbuf->b_ml.ml_line_count;
-      }
-    }
+    set_cmd_count(eap, n, validate);
   }
 
   return OK;
 }
 
+/// Check if command is not implemented
+bool is_cmd_ni(cmdidx_T cmdidx)
+{
+  return !IS_USER_CMDIDX(cmdidx) && (cmdnames[cmdidx].cmd_func == ex_ni
+                                     || cmdnames[cmdidx].cmd_func == ex_script_ni);
+}
+
 /// Parse command line and return information about the first command.
 ///
 /// @param cmdline Command line string
@@ -1394,14 +1447,17 @@ bool parse_cmdline(char *cmdline, exarg_T *eap, CmdParseInfo *cmdinfo, char **er
   if (eap->save_msg_silent != -1) {
     cmdinfo->silent = !!msg_silent;
     msg_silent = eap->save_msg_silent;
+    eap->save_msg_silent = -1;
   }
   if (eap->did_esilent) {
     cmdinfo->emsg_silent = true;
     emsg_silent--;
+    eap->did_esilent = false;
   }
   if (eap->did_sandbox) {
     cmdinfo->sandbox = true;
     sandbox--;
+    eap->did_sandbox = false;
   }
   if (cmdmod.save_ei != NULL) {
     cmdinfo->noautocmd = true;
@@ -1411,6 +1467,7 @@ bool parse_cmdline(char *cmdline, exarg_T *eap, CmdParseInfo *cmdinfo, char **er
   if (eap->verbose_save != -1) {
     cmdinfo->verbose = p_verbose;
     p_verbose = eap->verbose_save;
+    eap->verbose_save = -1;
   } else {
     cmdinfo->verbose = -1;
   }
@@ -1424,7 +1481,7 @@ bool parse_cmdline(char *cmdline, exarg_T *eap, CmdParseInfo *cmdinfo, char **er
   if (*eap->cmd == '*') {
     eap->cmd = skipwhite(eap->cmd + 1);
   }
-  p = find_command(eap, NULL);
+  p = find_ex_command(eap, NULL);
 
   // Set command address type and parse command range
   set_cmd_addr_type(eap, (char_u *)p);
@@ -1494,7 +1551,7 @@ bool parse_cmdline(char *cmdline, exarg_T *eap, CmdParseInfo *cmdinfo, char **er
   }
   // Set default range for command if required
   if ((eap->argt & EX_DFLALL) && eap->addr_count == 0) {
-    set_cmd_default_range(eap);
+    set_cmd_dflall_range(eap);
   }
 
   // Parse register and count
@@ -1519,6 +1576,148 @@ bool parse_cmdline(char *cmdline, exarg_T *eap, CmdParseInfo *cmdinfo, char **er
   return true;
 }
 
+/// Execute an Ex command using parsed command line information.
+/// Does not do any validation of the Ex command arguments.
+///
+/// @param eap Ex-command arguments
+/// @param cmdinfo Command parse information
+void execute_cmd(exarg_T *eap, CmdParseInfo *cmdinfo)
+{
+#define ERROR(msg) \
+  do { \
+    emsg(msg); \
+    goto end; \
+  } while (0)
+
+  char *errormsg = NULL;
+  cmdmod_T save_cmdmod = cmdmod;
+  cmdmod = cmdinfo->cmdmod;
+
+  // Apply command modifiers
+  if (cmdinfo->silent) {
+    eap->save_msg_silent = msg_silent;
+    msg_silent++;
+  }
+  if (cmdinfo->emsg_silent) {
+    eap->did_esilent = true;
+    emsg_silent++;
+  }
+  if (cmdinfo->sandbox) {
+    eap->did_sandbox = true;
+    sandbox++;
+  }
+  if (cmdinfo->noautocmd) {
+    cmdmod.save_ei = (char *)vim_strsave(p_ei);
+    set_string_option_direct("ei", -1, (char_u *)"all", OPT_FREE, SID_NONE);
+  }
+  if (cmdinfo->verbose != -1) {
+    eap->verbose_save = p_verbose;
+    p_verbose = cmdinfo->verbose;
+  }
+
+  if (!MODIFIABLE(curbuf) && (eap->argt & EX_MODIFY)
+      // allow :put in terminals
+      && !(curbuf->terminal && eap->cmdidx == CMD_put)) {
+    ERROR(_(e_modifiable));
+  }
+  if (text_locked() && !(eap->argt & EX_CMDWIN)
+      && !IS_USER_CMDIDX(eap->cmdidx)) {
+    ERROR(_(get_text_locked_msg()));
+  }
+  // Disallow editing another buffer when "curbuf->b_ro_locked" is set.
+  // Do allow ":checktime" (it is postponed).
+  // Do allow ":edit" (check for an argument later).
+  // Do allow ":file" with no arguments
+  if (!(eap->argt & EX_CMDWIN)
+      && eap->cmdidx != CMD_checktime
+      && eap->cmdidx != CMD_edit
+      && !(eap->cmdidx == CMD_file && *eap->arg == NUL)
+      && !IS_USER_CMDIDX(eap->cmdidx)
+      && curbuf_locked()) {
+    ERROR(_(e_cannot_edit_other_buf));
+  }
+
+  if (((eap->argt & EX_WHOLEFOLD) || eap->addr_count >= 2) && !global_busy
+      && eap->addr_type == ADDR_LINES) {
+    // Put the first line at the start of a closed fold, put the last line
+    // at the end of a closed fold.
+    (void)hasFolding(eap->line1, &eap->line1, NULL);
+    (void)hasFolding(eap->line2, NULL, &eap->line2);
+  }
+
+  // If filename expansion is enabled, expand filenames
+  if (cmdinfo->magic.file) {
+    if (expand_filename(eap, (char_u **)eap->cmdlinep, &errormsg) == FAIL) {
+      ERROR(errormsg);
+    }
+  }
+
+  // Accept buffer name.  Cannot be used at the same time with a buffer
+  // number.  Don't do this for a user command.
+  if ((eap->argt & EX_BUFNAME) && *eap->arg != NUL && eap->addr_count == 0
+      && !IS_USER_CMDIDX(eap->cmdidx)) {
+    if (eap->args == NULL) {
+      // If argument positions are not specified, search the argument for the buffer name.
+      // :bdelete, :bwipeout and :bunload take several arguments, separated by spaces:
+      // find next space (skipping over escaped characters).
+      // The others take one argument: ignore trailing spaces.
+      char *p;
+
+      if (eap->cmdidx == CMD_bdelete || eap->cmdidx == CMD_bwipeout
+          || eap->cmdidx == CMD_bunload) {
+        p = (char *)skiptowhite_esc((char_u *)eap->arg);
+      } else {
+        p = eap->arg + STRLEN(eap->arg);
+        while (p > eap->arg && ascii_iswhite(p[-1])) {
+          p--;
+        }
+      }
+      eap->line2 = buflist_findpat((char_u *)eap->arg, (char_u *)p, (eap->argt & EX_BUFUNL) != 0,
+                                   false, false);
+      eap->addr_count = 1;
+      eap->arg = skipwhite(p);
+    } else {
+      // If argument positions are specified, just use the first argument
+      eap->line2 = buflist_findpat((char_u *)eap->args[0],
+                                   (char_u *)(eap->args[0] + eap->arglens[0]),
+                                   (eap->argt & EX_BUFUNL) != 0, false, false);
+      eap->addr_count = 1;
+      // Shift each argument by 1
+      if (eap->args != NULL) {
+        for (size_t i = 0; i < eap->argc - 1; i++) {
+          eap->args[i] = eap->args[i + 1];
+        }
+        // Make the last argument point to the NUL terminator at the end of string
+        eap->args[eap->argc - 1] = eap->args[eap->argc - 1] + eap->arglens[eap->argc - 1];
+        eap->argc -= 1;
+      }
+      eap->arg = eap->args[0];
+    }
+    if (eap->line2 < 0) {  // failed
+      goto end;
+    }
+  }
+
+  // Execute the command
+  if (IS_USER_CMDIDX(eap->cmdidx)) {
+    // Execute a user-defined command.
+    do_ucmd(eap);
+  } else {
+    // Call the function to execute the command.
+    eap->errmsg = NULL;
+    (cmdnames[eap->cmdidx].cmd_func)(eap);
+    if (eap->errmsg != NULL) {
+      ERROR(_(eap->errmsg));
+    }
+  }
+end:
+  // Undo command modifiers
+  undo_cmdmod(eap, msg_scroll);
+  cmdmod = save_cmdmod;
+
+#undef ERROR
+}
+
 /// Execute one Ex command.
 ///
 /// If 'sourcing' is TRUE, the command will be included in the error message.
@@ -1606,7 +1805,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
   if (*ea.cmd == '*') {
     ea.cmd = skipwhite(ea.cmd + 1);
   }
-  p = find_command(&ea, NULL);
+  p = find_ex_command(&ea, NULL);
 
   // Count this line for profiling if skip is TRUE.
   if (do_profiling == PROF_YES
@@ -1732,7 +1931,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
     xfree(p);
     // If the autocommands did something and didn't cause an error, try
     // finding the command again.
-    p = (ret && !aborting()) ? find_command(&ea, NULL) : ea.cmd;
+    p = (ret && !aborting()) ? find_ex_command(&ea, NULL) : ea.cmd;
   }
 
   if (p == NULL) {
@@ -1759,10 +1958,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
   }
 
   // set when Not Implemented
-  const int ni = !IS_USER_CMDIDX(ea.cmdidx)
-                 && (cmdnames[ea.cmdidx].cmd_func == ex_ni
-                     || cmdnames[ea.cmdidx].cmd_func == ex_script_ni);
-
+  const int ni = is_cmd_ni(ea.cmdidx);
 
   // Forced commands.
   if (*p == '!' && ea.cmdidx != CMD_substitute
@@ -1976,7 +2172,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
   }
 
   if ((ea.argt & EX_DFLALL) && ea.addr_count == 0) {
-    set_cmd_default_range(&ea);
+    set_cmd_dflall_range(&ea);
   }
 
   // Parse register and count
@@ -2544,6 +2740,7 @@ static void undo_cmdmod(const exarg_T *eap, int save_msg_scroll)
 }
 
 
+
 /// Parse the address range, if any, in "eap".
 /// May set the last search pattern, unless "silent" is true.
 ///
@@ -2557,47 +2754,7 @@ int parse_cmd_address(exarg_T *eap, char **errormsg, bool silent)
   // Repeat for all ',' or ';' separated addresses.
   for (;;) {
     eap->line1 = eap->line2;
-    switch (eap->addr_type) {
-    case ADDR_LINES:
-    case ADDR_OTHER:
-      // Default is the cursor line number.  Avoid using an invalid
-      // line number though.
-      if (curwin->w_cursor.lnum > curbuf->b_ml.ml_line_count) {
-        eap->line2 = curbuf->b_ml.ml_line_count;
-      } else {
-        eap->line2 = curwin->w_cursor.lnum;
-      }
-      break;
-    case ADDR_WINDOWS:
-      eap->line2 = CURRENT_WIN_NR;
-      break;
-    case ADDR_ARGUMENTS:
-      eap->line2 = curwin->w_arg_idx + 1;
-      if (eap->line2 > ARGCOUNT) {
-        eap->line2 = ARGCOUNT;
-      }
-      break;
-    case ADDR_LOADED_BUFFERS:
-    case ADDR_BUFFERS:
-      eap->line2 = curbuf->b_fnum;
-      break;
-    case ADDR_TABS:
-      eap->line2 = CURRENT_TAB_NR;
-      break;
-    case ADDR_TABS_RELATIVE:
-    case ADDR_UNSIGNED:
-      eap->line2 = 1;
-      break;
-    case ADDR_QUICKFIX:
-      eap->line2 = (linenr_T)qf_get_cur_idx(eap);
-      break;
-    case ADDR_QUICKFIX_VALID:
-      eap->line2 = qf_get_cur_valid_idx(eap);
-      break;
-    case ADDR_NONE:
-      // Will give an error later if a range is found.
-      break;
-    }
+    eap->line2 = get_cmd_default_range(eap);
     eap->cmd = skipwhite(eap->cmd);
     lnum = get_address(eap, &eap->cmd, eap->addr_type, eap->skip, silent,
                        eap->addr_count == 0, address_count++);
@@ -2772,7 +2929,7 @@ static void append_command(char *cmd)
 /// "full" is set to TRUE if the whole command name matched.
 ///
 /// @return  NULL for an ambiguous user command.
-static char *find_command(exarg_T *eap, int *full)
+char *find_ex_command(exarg_T *eap, int *full)
   FUNC_ATTR_NONNULL_ARG(1)
 {
   int len;
@@ -2859,7 +3016,7 @@ static char *find_command(exarg_T *eap, int *full)
 
     for (; (int)eap->cmdidx < CMD_SIZE;
          eap->cmdidx = (cmdidx_T)((int)eap->cmdidx + 1)) {
-      if (STRNCMP(cmdnames[(int)eap->cmdidx].cmd_name, (char *)eap->cmd,
+      if (STRNCMP(cmdnames[(int)eap->cmdidx].cmd_name, eap->cmd,
                   (size_t)len) == 0) {
         if (full != NULL
             && cmdnames[(int)eap->cmdidx].cmd_name[len] == NUL) {
@@ -3076,7 +3233,7 @@ int cmd_exists(const char *const name)
   ea.cmd = (char *)((*name == '2' || *name == '3') ? name + 1 : name);
   ea.cmdidx = (cmdidx_T)0;
   int full = false;
-  p = find_command(&ea, &full);
+  p = find_ex_command(&ea, &full);
   if (p == NULL) {
     return 3;
   }
@@ -3108,7 +3265,7 @@ void f_fullcommand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
   ea.cmd = (*name == '2' || *name == '3') ? name + 1 : name;
   ea.cmdidx = (cmdidx_T)0;
-  char *p = find_command(&ea, NULL);
+  char *p = find_ex_command(&ea, NULL);
   if (p == NULL || ea.cmdidx == CMD_SIZE) {
     return;
   }
@@ -3431,7 +3588,7 @@ const char *set_one_cmd_context(expand_T *xp, const char *buff)
       xp->xp_shell = TRUE;
 #endif
       // When still after the command name expand executables.
-      if ((char_u *)xp->xp_pattern == (char_u *)skipwhite(arg)) {
+      if (xp->xp_pattern == skipwhite(arg)) {
         xp->xp_context = EXPAND_SHELLCMD;
       }
     }
@@ -4416,7 +4573,7 @@ static void ex_script_ni(exarg_T *eap)
 /// Check range in Ex command for validity.
 ///
 /// @return  NULL when valid, error message when invalid.
-static char *invalid_range(exarg_T *eap)
+char *invalid_range(exarg_T *eap)
 {
   buf_T *buf;
   if (eap->line1 < 0 || eap->line2 < 0 || eap->line1 > eap->line2) {
@@ -4535,7 +4692,7 @@ static char *skip_grep_pat(exarg_T *eap)
 
 /// For the ":make" and ":grep" commands insert the 'makeprg'/'grepprg' option
 /// in the command line, so that things like % get expanded.
-static char *replace_makeprg(exarg_T *eap, char *p, char **cmdlinep)
+char *replace_makeprg(exarg_T *eap, char *p, char **cmdlinep)
 {
   char *new_cmdline;
   char *program;
@@ -4773,7 +4930,7 @@ int expand_filename(exarg_T *eap, char_u **cmdlinep, char **errormsgp)
   return OK;
 }
 
-/// Replace part of the command line, keeping eap->cmd, eap->arg and
+/// Replace part of the command line, keeping eap->cmd, eap->arg, eap->args and
 /// eap->nextcmd correct.
 /// "src" points to the part that is to be replaced, of length "srclen".
 /// "repl" is the replacement string.
@@ -4792,6 +4949,7 @@ static char *repl_cmdline(exarg_T *eap, char *src, size_t srclen, char *repl, ch
     i += STRLEN(eap->nextcmd);    // add space for next command
   }
   char *new_cmdline = xmalloc(i);
+  size_t offset = (size_t)(src - *cmdlinep);
 
   /*
    * Copy the stuff before the expanded part.
@@ -4799,7 +4957,7 @@ static char *repl_cmdline(exarg_T *eap, char *src, size_t srclen, char *repl, ch
    * Copy what came after the expanded part.
    * Copy the next commands, if there are any.
    */
-  i = (size_t)(src - *cmdlinep);   // length of part before match
+  i = offset;   // length of part before match
   memmove(new_cmdline, *cmdlinep, i);
 
   memmove(new_cmdline + i, repl, len);
@@ -4814,6 +4972,19 @@ static char *repl_cmdline(exarg_T *eap, char *src, size_t srclen, char *repl, ch
   }
   eap->cmd = new_cmdline + (eap->cmd - *cmdlinep);
   eap->arg = new_cmdline + (eap->arg - *cmdlinep);
+
+  for (size_t j = 0; j < eap->argc; j++) {
+    if (offset >= (size_t)(eap->args[j] - *cmdlinep)) {
+      // If replaced text is after or in the same position as the argument,
+      // the argument's position relative to the beginning of the cmdline stays the same.
+      eap->args[j] = new_cmdline + (eap->args[j] - *cmdlinep);
+    } else {
+      // Otherwise, argument gets shifted alongside the replaced text.
+      // The amount of the shift is equal to the difference of the old and new string length.
+      eap->args[j] = new_cmdline + (eap->args[j] - *cmdlinep) + (len - srclen);
+    }
+  }
+
   if (eap->do_ecmd_cmd != NULL && eap->do_ecmd_cmd != dollar_command) {
     eap->do_ecmd_cmd = new_cmdline + (eap->do_ecmd_cmd - *cmdlinep);
   }
@@ -6002,7 +6173,7 @@ bool uc_split_args_iter(const char *arg, size_t arglen, size_t *end, char *buf,
 }
 
 /// split and quote args for <f-args>
-static char *uc_split_args(char *arg, size_t *lenp)
+static char *uc_split_args(char *arg, char **args, size_t *arglens, size_t argc, size_t *lenp)
 {
   char *buf;
   char *p;
@@ -6010,61 +6181,107 @@ static char *uc_split_args(char *arg, size_t *lenp)
   int len;
 
   // Precalculate length
-  p = arg;
   len = 2;   // Initial and final quotes
+  if (args == NULL) {
+    p = arg;
 
-  while (*p) {
-    if (p[0] == '\\' && p[1] == '\\') {
-      len += 2;
-      p += 2;
-    } else if (p[0] == '\\' && ascii_iswhite(p[1])) {
-      len += 1;
-      p += 2;
-    } else if (*p == '\\' || *p == '"') {
-      len += 2;
-      p += 1;
-    } else if (ascii_iswhite(*p)) {
-      p = skipwhite(p);
-      if (*p == NUL) {
-        break;
+    while (*p) {
+      if (p[0] == '\\' && p[1] == '\\') {
+        len += 2;
+        p += 2;
+      } else if (p[0] == '\\' && ascii_iswhite(p[1])) {
+        len += 1;
+        p += 2;
+      } else if (*p == '\\' || *p == '"') {
+        len += 2;
+        p += 1;
+      } else if (ascii_iswhite(*p)) {
+        p = skipwhite(p);
+        if (*p == NUL) {
+          break;
+        }
+        len += 3;       // ","
+      } else {
+        const int charlen = utfc_ptr2len(p);
+
+        len += charlen;
+        p += charlen;
       }
-      len += 3;       // ","
-    } else {
-      const int charlen = utfc_ptr2len(p);
+    }
+  } else {
+    for (size_t i = 0; i < argc; i++) {
+      p = args[i];
+      const char *arg_end = args[i] + arglens[i];
+
+      while (p < arg_end) {
+        if (*p == '\\' || *p == '"') {
+          len += 2;
+          p += 1;
+        } else {
+          const int charlen = utfc_ptr2len(p);
 
-      len += charlen;
-      p += charlen;
+          len += charlen;
+          p += charlen;
+        }
+      }
+
+      if (i != argc - 1) {
+        len += 3;  // ","
+      }
     }
   }
 
   buf = xmalloc((size_t)len + 1);
 
-  p = arg;
   q = buf;
   *q++ = '"';
-  while (*p) {
-    if (p[0] == '\\' && p[1] == '\\') {
-      *q++ = '\\';
-      *q++ = '\\';
-      p += 2;
-    } else if (p[0] == '\\' && ascii_iswhite(p[1])) {
-      *q++ = p[1];
-      p += 2;
-    } else if (*p == '\\' || *p == '"') {
-      *q++ = '\\';
-      *q++ = *p++;
-    } else if (ascii_iswhite(*p)) {
-      p = skipwhite(p);
-      if (*p == NUL) {
-        break;
+
+  if (args == NULL) {
+    p = arg;
+    while (*p) {
+      if (p[0] == '\\' && p[1] == '\\') {
+        *q++ = '\\';
+        *q++ = '\\';
+        p += 2;
+      } else if (p[0] == '\\' && ascii_iswhite(p[1])) {
+        *q++ = p[1];
+        p += 2;
+      } else if (*p == '\\' || *p == '"') {
+        *q++ = '\\';
+        *q++ = *p++;
+      } else if (ascii_iswhite(*p)) {
+        p = skipwhite(p);
+        if (*p == NUL) {
+          break;
+        }
+        *q++ = '"';
+        *q++ = ',';
+        *q++ = '"';
+      } else {
+        mb_copy_char((const char_u **)&p, (char_u **)&q);
+      }
+    }
+  } else {
+    for (size_t i = 0; i < argc; i++) {
+      p = args[i];
+      const char *arg_end = args[i] + arglens[i];
+
+      while (p < arg_end) {
+        if (*p == '\\' || *p == '"') {
+          *q++ = '\\';
+          *q++ = *p++;
+        } else {
+          mb_copy_char((const char_u **)&p, (char_u **)&q);
+        }
+      }
+      if (i != argc - 1) {
+        *q++ = '"';
+        *q++ = ',';
+        *q++ = '"';
       }
-      *q++ = '"';
-      *q++ = ',';
-      *q++ = '"';
-    } else {
-      mb_copy_char((const char_u **)&p, (char_u **)&q);
     }
   }
+
   *q++ = '"';
   *q = 0;
 
@@ -6201,7 +6418,7 @@ static size_t uc_check_code(char *code, size_t len, char *buf, ucmd_T *cmd, exar
     case 2:     // Quote and split (<f-args>)
       // This is hard, so only do it once, and cache the result
       if (*split_buf == NULL) {
-        *split_buf = uc_split_args(eap->arg, split_len);
+        *split_buf = uc_split_args(eap->arg, eap->args, eap->arglens, eap->argc, split_len);
       }
 
       result = *split_len;
@@ -9887,7 +10104,7 @@ bool cmd_can_preview(char *cmd)
   if (*ea.cmd == '*') {
     ea.cmd = skipwhite(ea.cmd + 1);
   }
-  char *end = find_command(&ea, NULL);
+  char *end = find_ex_command(&ea, NULL);
 
   switch (ea.cmdidx) {
   case CMD_substitute:
@@ -10278,3 +10495,9 @@ void verify_command(char *cmd)
   msg("`      `.:.`.,:iii;;;;;;;;iii;;;:`       `.``                 "
       "                                       `nW");
 }
+
+/// Get argt of command with id
+uint32_t get_cmd_argt(cmdidx_T cmdidx)
+{
+  return cmdnames[(int)cmdidx].cmd_argt;
+}
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 8792e9673a..d651c1f014 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -33,6 +33,7 @@
 #include "nvim/func_attr.h"
 #include "nvim/garray.h"
 #include "nvim/getchar.h"
+#include "nvim/globals.h"
 #include "nvim/highlight.h"
 #include "nvim/highlight_defs.h"
 #include "nvim/highlight_group.h"
@@ -2522,7 +2523,7 @@ char *get_text_locked_msg(void)
 bool curbuf_locked(void)
 {
   if (curbuf->b_ro_locked > 0) {
-    emsg(_("E788: Not allowed to edit another buffer now"));
+    emsg(_(e_cannot_edit_other_buf));
     return true;
   }
   return allbuf_locked();
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 620af9444c..ecf358c4a9 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -997,6 +997,7 @@ EXTERN char e_listarg[] INIT(= N_("E686: Argument of %s must be a List"));
 EXTERN char e_unsupportedoption[] INIT(= N_("E519: Option not supported"));
 EXTERN char e_fnametoolong[] INIT(= N_("E856: Filename too long"));
 EXTERN char e_float_as_string[] INIT(= N_("E806: using Float as a String"));
+EXTERN char e_cannot_edit_other_buf[] INIT(= N_("E788: Not allowed to edit another buffer now"));
 
 EXTERN char e_autocmd_err[] INIT(= N_("E5500: autocmd has thrown an exception: %s"));
 EXTERN char e_cmdmap_err[] INIT(= N_("E5520: <Cmd> mapping must end with <CR>"));
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 1da868c137..7d08481a7b 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -1863,8 +1863,8 @@ void nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap)
   if (cmd->uc_argt & EX_NOSPC) {
     // Commands where nargs = 1 or "?" fargs is the same as args
     lua_rawseti(lstate, -2, 1);
-  } else {
-    // Commands with more than one possible argument we split
+  } else if (eap->args == NULL) {
+    // For commands with more than one possible argument, split if argument list isn't available.
     lua_pop(lstate, 1);  // Pop the reference of opts.args
     size_t length = STRLEN(eap->arg);
     size_t end = 0;
@@ -1881,6 +1881,13 @@ void nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap)
       }
     }
     xfree(buf);
+  } else {
+    // If argument list is available, just use it.
+    lua_pop(lstate, 1);
+    for (size_t i = 0; i < eap->argc; i++) {
+      lua_pushlstring(lstate, eap->args[i], eap->arglens[i]);
+      lua_rawseti(lstate, -2, (int)i + 1);
+    }
   }
   lua_setfield(lstate, -2, "fargs");