vim-patch:8.1.1210: support for user commands is spread out (#19653)

Problem:    Support for user commands is spread out. No good reason to make
            user commands optional.
Solution:   Move user command support to usercmd.c.  Always enable the
            user_commands feature.
https://github.com/vim/vim/commit/ac9fb18020d7e8bf16d02d45fbb02cf47328aaf7

9 files changed, 1781 insertions, 1739 deletions

diff --git a/src/nvim/api/command.c b/src/nvim/api/command.c
index 04242932c9..bc766ff39c 100644
--- a/src/nvim/api/command.c
+++ b/src/nvim/api/command.c
@@ -14,6 +14,7 @@
 #include "nvim/lua/executor.h"
 #include "nvim/ops.h"
 #include "nvim/regexp.h"
+#include "nvim/usercmd.h"
 #include "nvim/window.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 671f0db077..b5e100edcb 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -76,6 +76,7 @@
 #include "nvim/syntax.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
+#include "nvim/usercmd.h"
 #include "nvim/version.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index e3d61ef7e2..422f195198 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -9,7 +9,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "nvim/api/private/helpers.h"
 #include "nvim/ascii.h"
 #include "nvim/buffer.h"
 #include "nvim/change.h"
@@ -80,24 +79,19 @@
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/undo_defs.h"
+#include "nvim/usercmd.h"
 #include "nvim/version.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
 
-static char e_no_such_user_defined_command_str[]
-  = N_("E184: No such user-defined command: %s");
 static char e_ambiguous_use_of_user_defined_command[]
   = N_("E464: Ambiguous use of user-defined command");
 static char e_not_an_editor_command[]
   = N_("E492: Not an editor command");
-static char e_no_such_user_defined_command_in_current_buffer_str[]
-  = N_("E1237: No such user-defined command in current buffer: %s");
 
 static int quitmore = 0;
 static bool ex_pressedreturn = false;
 
-garray_T ucmds = { 0, 0, sizeof(ucmd_T), 4, NULL };
-
 // Struct for storing a line inside a while/for loop
 typedef struct {
   char *line;            // command line
@@ -1632,9 +1626,8 @@ static int execute_cmd0(int *retv, exarg_T *eap, char **errormsg, bool preview)
     // Execute a user-defined command.
     *retv = do_ucmd(eap, preview);
   } else {
-    // Call the function to execute the command or the preview callback.
+    // Call the function to execute the builtin command or the preview callback.
     eap->errmsg = NULL;
-
     if (preview) {
       *retv = (cmdnames[eap->cmdidx].cmd_preview_func)(eap, cmdpreview_get_ns(),
                                                        cmdpreview_get_bufnr());
@@ -2036,6 +2029,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
     }
     goto doend;
   }
+
   // Check for wrong commands.
   if (ea.cmdidx == CMD_SIZE) {
     if (!ea.skip) {
@@ -3019,115 +3013,6 @@ char *find_ex_command(exarg_T *eap, int *full)
   return p;
 }
 
-/// Search for a user command that matches "eap->cmd".
-/// Return cmdidx in "eap->cmdidx", flags in "eap->argt", idx in "eap->useridx".
-/// Return a pointer to just after the command.
-/// Return NULL if there is no matching command.
-///
-/// @param *p      end of the command (possibly including count)
-/// @param full    set to TRUE for a full match
-/// @param xp      used for completion, NULL otherwise
-/// @param complp  completion flags or NULL
-static char *find_ucmd(exarg_T *eap, char *p, int *full, expand_T *xp, int *complp)
-{
-  int len = (int)(p - eap->cmd);
-  int j, k, matchlen = 0;
-  ucmd_T *uc;
-  bool found = false;
-  bool possible = false;
-  char *cp, *np;             // Point into typed cmd and test name
-  garray_T *gap;
-  bool amb_local = false;            // Found ambiguous buffer-local command,
-                                     // only full match global is accepted.
-
-  // Look for buffer-local user commands first, then global ones.
-  gap = &prevwin_curwin()->w_buffer->b_ucmds;
-  for (;;) {
-    for (j = 0; j < gap->ga_len; j++) {
-      uc = USER_CMD_GA(gap, j);
-      cp = eap->cmd;
-      np = (char *)uc->uc_name;
-      k = 0;
-      while (k < len && *np != NUL && *cp++ == *np++) {
-        k++;
-      }
-      if (k == len || (*np == NUL && ascii_isdigit(eap->cmd[k]))) {
-        /* If finding a second match, the command is ambiguous.  But
-         * not if a buffer-local command wasn't a full match and a
-         * global command is a full match. */
-        if (k == len && found && *np != NUL) {
-          if (gap == &ucmds) {
-            return NULL;
-          }
-          amb_local = true;
-        }
-
-        if (!found || (k == len && *np == NUL)) {
-          /* If we matched up to a digit, then there could
-           * be another command including the digit that we
-           * should use instead.
-           */
-          if (k == len) {
-            found = true;
-          } else {
-            possible = true;
-          }
-
-          if (gap == &ucmds) {
-            eap->cmdidx = CMD_USER;
-          } else {
-            eap->cmdidx = CMD_USER_BUF;
-          }
-          eap->argt = uc->uc_argt;
-          eap->useridx = j;
-          eap->addr_type = uc->uc_addr_type;
-
-          if (complp != NULL) {
-            *complp = uc->uc_compl;
-          }
-          if (xp != NULL) {
-            xp->xp_luaref = uc->uc_compl_luaref;
-            xp->xp_arg = (char *)uc->uc_compl_arg;
-            xp->xp_script_ctx = uc->uc_script_ctx;
-            xp->xp_script_ctx.sc_lnum += sourcing_lnum;
-          }
-          /* Do not search for further abbreviations
-           * if this is an exact match. */
-          matchlen = k;
-          if (k == len && *np == NUL) {
-            if (full != NULL) {
-              *full = TRUE;
-            }
-            amb_local = false;
-            break;
-          }
-        }
-      }
-    }
-
-    // Stop if we found a full match or searched all.
-    if (j < gap->ga_len || gap == &ucmds) {
-      break;
-    }
-    gap = &ucmds;
-  }
-
-  // Only found ambiguous matches.
-  if (amb_local) {
-    if (xp != NULL) {
-      xp->xp_context = EXPAND_UNSUCCESSFUL;
-    }
-    return NULL;
-  }
-
-  /* The match we found may be followed immediately by a number.  Move "p"
-   * back to point to it. */
-  if (found || possible) {
-    return p + (matchlen - len);
-  }
-  return p;
-}
-
 static struct cmdmod {
   char *name;
   int minlen;
@@ -3691,50 +3576,7 @@ const char *set_one_cmd_context(expand_T *xp, const char *buff)
    */
 
   case CMD_command:
-    // Check for attributes
-    while (*arg == '-') {
-      arg++;  // Skip "-".
-      p = (const char *)skiptowhite((const char_u *)arg);
-      if (*p == NUL) {
-        // Cursor is still in the attribute.
-        p = strchr(arg, '=');
-        if (p == NULL) {
-          // No "=", so complete attribute names.
-          xp->xp_context = EXPAND_USER_CMD_FLAGS;
-          xp->xp_pattern = (char *)arg;
-          return NULL;
-        }
-
-        // For the -complete, -nargs and -addr attributes, we complete
-        // their arguments as well.
-        if (STRNICMP(arg, "complete", p - arg) == 0) {
-          xp->xp_context = EXPAND_USER_COMPLETE;
-          xp->xp_pattern = (char *)p + 1;
-          return NULL;
-        } else if (STRNICMP(arg, "nargs", p - arg) == 0) {
-          xp->xp_context = EXPAND_USER_NARGS;
-          xp->xp_pattern = (char *)p + 1;
-          return NULL;
-        } else if (STRNICMP(arg, "addr", p - arg) == 0) {
-          xp->xp_context = EXPAND_USER_ADDR_TYPE;
-          xp->xp_pattern = (char *)p + 1;
-          return NULL;
-        }
-        return NULL;
-      }
-      arg = (const char *)skipwhite(p);
-    }
-
-    // After the attributes comes the new command name.
-    p = (const char *)skiptowhite((const char_u *)arg);
-    if (*p == NUL) {
-      xp->xp_context = EXPAND_USER_COMMANDS;
-      xp->xp_pattern = (char *)arg;
-      break;
-    }
-
-    // And finally comes a normal command.
-    return (const char *)skipwhite(p);
+    return set_context_in_user_cmd(xp, arg);
 
   case CMD_delcommand:
     xp->xp_context = EXPAND_USER_COMMANDS;
@@ -3930,6 +3772,7 @@ const char *set_one_cmd_context(expand_T *xp, const char *buff)
     xp->xp_context = EXPAND_DIFF_BUFFERS;
     xp->xp_pattern = (char *)arg;
     break;
+
   case CMD_USER:
   case CMD_USER_BUF:
     if (context != EXPAND_NOTHING) {
@@ -3951,7 +3794,7 @@ const char *set_one_cmd_context(expand_T *xp, const char *buff)
             // argument starts after a space
             arg = p + 1;
           } else if (*p == '\\' && *(p + 1) != NUL) {
-            p++;                // skip over escaped character
+            p++;  // skip over escaped character
           }
           MB_PTR_ADV(p);
         }
@@ -5417,1474 +5260,6 @@ char *get_command_name(expand_T *xp, int idx)
   return cmdnames[idx].cmd_name;
 }
 
-/// Check for a valid user command name
-///
-/// If the given {name} is valid, then a pointer to the end of the valid name is returned.
-/// Otherwise, returns NULL.
-char *uc_validate_name(char *name)
-{
-  if (ASCII_ISALPHA(*name)) {
-    while (ASCII_ISALNUM(*name)) {
-      name++;
-    }
-  }
-  if (!ends_excmd(*name) && !ascii_iswhite(*name)) {
-    return NULL;
-  }
-
-  return name;
-}
-
-/// Create a new user command {name}, if one doesn't already exist.
-///
-/// This function takes ownership of compl_arg, compl_luaref, and luaref.
-///
-/// @return  OK if the command is created, FAIL otherwise.
-int uc_add_command(char *name, size_t name_len, const char *rep, uint32_t argt, long def, int flags,
-                   int compl, char *compl_arg, LuaRef compl_luaref, LuaRef preview_luaref,
-                   cmd_addr_T addr_type, LuaRef luaref, bool force)
-  FUNC_ATTR_NONNULL_ARG(1, 3)
-{
-  ucmd_T *cmd = NULL;
-  int i;
-  int cmp = 1;
-  char *rep_buf = NULL;
-  garray_T *gap;
-
-  replace_termcodes(rep, STRLEN(rep), &rep_buf, 0, NULL, CPO_TO_CPO_FLAGS);
-  if (rep_buf == NULL) {
-    // Can't replace termcodes - try using the string as is
-    rep_buf = xstrdup(rep);
-  }
-
-  // get address of growarray: global or in curbuf
-  if (flags & UC_BUFFER) {
-    gap = &curbuf->b_ucmds;
-    if (gap->ga_itemsize == 0) {
-      ga_init(gap, (int)sizeof(ucmd_T), 4);
-    }
-  } else {
-    gap = &ucmds;
-  }
-
-  // Search for the command in the already defined commands.
-  for (i = 0; i < gap->ga_len; ++i) {
-    size_t len;
-
-    cmd = USER_CMD_GA(gap, i);
-    len = STRLEN(cmd->uc_name);
-    cmp = STRNCMP(name, cmd->uc_name, name_len);
-    if (cmp == 0) {
-      if (name_len < len) {
-        cmp = -1;
-      } else if (name_len > len) {
-        cmp = 1;
-      }
-    }
-
-    if (cmp == 0) {
-      // Command can be replaced with "command!" and when sourcing the
-      // same script again, but only once.
-      if (!force
-          && (cmd->uc_script_ctx.sc_sid != current_sctx.sc_sid
-              || cmd->uc_script_ctx.sc_seq == current_sctx.sc_seq)) {
-        semsg(_("E174: Command already exists: add ! to replace it: %s"),
-              name);
-        goto fail;
-      }
-
-      XFREE_CLEAR(cmd->uc_rep);
-      XFREE_CLEAR(cmd->uc_compl_arg);
-      NLUA_CLEAR_REF(cmd->uc_luaref);
-      NLUA_CLEAR_REF(cmd->uc_compl_luaref);
-      NLUA_CLEAR_REF(cmd->uc_preview_luaref);
-      break;
-    }
-
-    // Stop as soon as we pass the name to add
-    if (cmp < 0) {
-      break;
-    }
-  }
-
-  // Extend the array unless we're replacing an existing command
-  if (cmp != 0) {
-    ga_grow(gap, 1);
-
-    char *const p = xstrnsave(name, name_len);
-
-    cmd = USER_CMD_GA(gap, i);
-    memmove(cmd + 1, cmd, (size_t)(gap->ga_len - i) * sizeof(ucmd_T));
-
-    ++gap->ga_len;
-
-    cmd->uc_name = (char_u *)p;
-  }
-
-  cmd->uc_rep = (char_u *)rep_buf;
-  cmd->uc_argt = argt;
-  cmd->uc_def = def;
-  cmd->uc_compl = compl;
-  cmd->uc_script_ctx = current_sctx;
-  cmd->uc_script_ctx.sc_lnum += sourcing_lnum;
-  nlua_set_sctx(&cmd->uc_script_ctx);
-  cmd->uc_compl_arg = (char_u *)compl_arg;
-  cmd->uc_compl_luaref = compl_luaref;
-  cmd->uc_preview_luaref = preview_luaref;
-  cmd->uc_addr_type = addr_type;
-  cmd->uc_luaref = luaref;
-
-  return OK;
-
-fail:
-  xfree(rep_buf);
-  xfree(compl_arg);
-  NLUA_CLEAR_REF(luaref);
-  NLUA_CLEAR_REF(compl_luaref);
-  NLUA_CLEAR_REF(preview_luaref);
-  return FAIL;
-}
-
-static struct {
-  cmd_addr_T expand;
-  char *name;
-  char *shortname;
-} addr_type_complete[] =
-{
-  { ADDR_ARGUMENTS, "arguments", "arg" },
-  { ADDR_LINES, "lines", "line" },
-  { ADDR_LOADED_BUFFERS, "loaded_buffers", "load" },
-  { ADDR_TABS, "tabs", "tab" },
-  { ADDR_BUFFERS, "buffers", "buf" },
-  { ADDR_WINDOWS, "windows", "win" },
-  { ADDR_QUICKFIX, "quickfix", "qf" },
-  { ADDR_OTHER, "other", "?" },
-  { ADDR_NONE, NULL, NULL }
-};
-
-/*
- * List of names for completion for ":command" with the EXPAND_ flag.
- * Must be alphabetical for completion.
- */
-static const char *command_complete[] =
-{
-  [EXPAND_ARGLIST] = "arglist",
-  [EXPAND_AUGROUP] = "augroup",
-  [EXPAND_BEHAVE] = "behave",
-  [EXPAND_BUFFERS] = "buffer",
-  [EXPAND_CHECKHEALTH] = "checkhealth",
-  [EXPAND_COLORS] = "color",
-  [EXPAND_COMMANDS] = "command",
-  [EXPAND_COMPILER] = "compiler",
-  [EXPAND_CSCOPE] = "cscope",
-  [EXPAND_USER_DEFINED] = "custom",
-  [EXPAND_USER_LIST] = "customlist",
-  [EXPAND_USER_LUA] = "<Lua function>",
-  [EXPAND_DIFF_BUFFERS] = "diff_buffer",
-  [EXPAND_DIRECTORIES] = "dir",
-  [EXPAND_ENV_VARS] = "environment",
-  [EXPAND_EVENTS] = "event",
-  [EXPAND_EXPRESSION] = "expression",
-  [EXPAND_FILES] = "file",
-  [EXPAND_FILES_IN_PATH] = "file_in_path",
-  [EXPAND_FILETYPE] = "filetype",
-  [EXPAND_FUNCTIONS] = "function",
-  [EXPAND_HELP] = "help",
-  [EXPAND_HIGHLIGHT] = "highlight",
-  [EXPAND_HISTORY] = "history",
-#ifdef HAVE_WORKING_LIBINTL
-  [EXPAND_LOCALES] = "locale",
-#endif
-  [EXPAND_LUA] = "lua",
-  [EXPAND_MAPCLEAR] = "mapclear",
-  [EXPAND_MAPPINGS] = "mapping",
-  [EXPAND_MENUS] = "menu",
-  [EXPAND_MESSAGES] = "messages",
-  [EXPAND_OWNSYNTAX] = "syntax",
-  [EXPAND_SYNTIME] = "syntime",
-  [EXPAND_SETTINGS] = "option",
-  [EXPAND_PACKADD] = "packadd",
-  [EXPAND_SHELLCMD] = "shellcmd",
-  [EXPAND_SIGN] = "sign",
-  [EXPAND_TAGS] = "tag",
-  [EXPAND_TAGS_LISTFILES] = "tag_listfiles",
-  [EXPAND_USER] = "user",
-  [EXPAND_USER_VARS] = "var",
-};
-
-static char *get_command_complete(int arg)
-{
-  if (arg >= (int)(ARRAY_SIZE(command_complete))) {
-    return NULL;
-  } else {
-    return (char *)command_complete[arg];
-  }
-}
-
-static void uc_list(char *name, size_t name_len)
-{
-  int i, j;
-  bool found = false;
-  ucmd_T *cmd;
-  uint32_t a;
-
-  // In cmdwin, the alternative buffer should be used.
-  const garray_T *gap = &prevwin_curwin()->w_buffer->b_ucmds;
-  for (;;) {
-    for (i = 0; i < gap->ga_len; i++) {
-      cmd = USER_CMD_GA(gap, i);
-      a = cmd->uc_argt;
-
-      // Skip commands which don't match the requested prefix and
-      // commands filtered out.
-      if (STRNCMP(name, cmd->uc_name, name_len) != 0
-          || message_filtered(cmd->uc_name)) {
-        continue;
-      }
-
-      // Put out the title first time
-      if (!found) {
-        msg_puts_title(_("\n    Name              Args Address "
-                         "Complete    Definition"));
-      }
-      found = true;
-      msg_putchar('\n');
-      if (got_int) {
-        break;
-      }
-
-      // Special cases
-      int len = 4;
-      if (a & EX_BANG) {
-        msg_putchar('!');
-        len--;
-      }
-      if (a & EX_REGSTR) {
-        msg_putchar('"');
-        len--;
-      }
-      if (gap != &ucmds) {
-        msg_putchar('b');
-        len--;
-      }
-      if (a & EX_TRLBAR) {
-        msg_putchar('|');
-        len--;
-      }
-      while (len-- > 0) {
-        msg_putchar(' ');
-      }
-
-      msg_outtrans_attr(cmd->uc_name, HL_ATTR(HLF_D));
-      len = (int)STRLEN(cmd->uc_name) + 4;
-
-      do {
-        msg_putchar(' ');
-        len++;
-      } while (len < 22);
-
-      // "over" is how much longer the name is than the column width for
-      // the name, we'll try to align what comes after.
-      const int over = len - 22;
-      len = 0;
-
-      // Arguments
-      switch (a & (EX_EXTRA | EX_NOSPC | EX_NEEDARG)) {
-      case 0:
-        IObuff[len++] = '0';
-        break;
-      case (EX_EXTRA):
-        IObuff[len++] = '*';
-        break;
-      case (EX_EXTRA | EX_NOSPC):
-        IObuff[len++] = '?';
-        break;
-      case (EX_EXTRA | EX_NEEDARG):
-        IObuff[len++] = '+';
-        break;
-      case (EX_EXTRA | EX_NOSPC | EX_NEEDARG):
-        IObuff[len++] = '1';
-        break;
-      }
-
-      do {
-        IObuff[len++] = ' ';
-      } while (len < 5 - over);
-
-      // Address / Range
-      if (a & (EX_RANGE | EX_COUNT)) {
-        if (a & EX_COUNT) {
-          // -count=N
-          snprintf((char *)IObuff + len, IOSIZE, "%" PRId64 "c",
-                   (int64_t)cmd->uc_def);
-          len += (int)STRLEN(IObuff + len);
-        } else if (a & EX_DFLALL) {
-          IObuff[len++] = '%';
-        } else if (cmd->uc_def >= 0) {
-          // -range=N
-          snprintf((char *)IObuff + len, IOSIZE, "%" PRId64 "",
-                   (int64_t)cmd->uc_def);
-          len += (int)STRLEN(IObuff + len);
-        } else {
-          IObuff[len++] = '.';
-        }
-      }
-
-      do {
-        IObuff[len++] = ' ';
-      } while (len < 8 - over);
-
-      // Address Type
-      for (j = 0; addr_type_complete[j].expand != ADDR_NONE; j++) {
-        if (addr_type_complete[j].expand != ADDR_LINES
-            && addr_type_complete[j].expand == cmd->uc_addr_type) {
-          STRCPY(IObuff + len, addr_type_complete[j].shortname);
-          len += (int)STRLEN(IObuff + len);
-          break;
-        }
-      }
-
-      do {
-        IObuff[len++] = ' ';
-      } while (len < 13 - over);
-
-      // Completion
-      char *cmd_compl = get_command_complete(cmd->uc_compl);
-      if (cmd_compl != NULL) {
-        STRCPY(IObuff + len, get_command_complete(cmd->uc_compl));
-        len += (int)STRLEN(IObuff + len);
-      }
-
-      do {
-        IObuff[len++] = ' ';
-      } while (len < 25 - over);
-
-      IObuff[len] = '\0';
-      msg_outtrans((char *)IObuff);
-
-      if (cmd->uc_luaref != LUA_NOREF) {
-        char *fn = nlua_funcref_str(cmd->uc_luaref);
-        msg_puts_attr(fn, HL_ATTR(HLF_8));
-        xfree(fn);
-        // put the description on a new line
-        if (*cmd->uc_rep != NUL) {
-          msg_puts("\n                                               ");
-        }
-      }
-
-      msg_outtrans_special(cmd->uc_rep, false,
-                           name_len == 0 ? Columns - 47 : 0);
-      if (p_verbose > 0) {
-        last_set_msg(cmd->uc_script_ctx);
-      }
-      line_breakcheck();
-      if (got_int) {
-        break;
-      }
-    }
-    if (gap == &ucmds || i < gap->ga_len) {
-      break;
-    }
-    gap = &ucmds;
-  }
-
-  if (!found) {
-    msg(_("No user-defined commands found"));
-  }
-}
-
-static int uc_scan_attr(char *attr, size_t len, uint32_t *argt, long *def, int *flags, int *complp,
-                        char_u **compl_arg, cmd_addr_T *addr_type_arg)
-  FUNC_ATTR_NONNULL_ALL
-{
-  char *p;
-
-  if (len == 0) {
-    emsg(_("E175: No attribute specified"));
-    return FAIL;
-  }
-
-  // First, try the simple attributes (no arguments)
-  if (STRNICMP(attr, "bang", len) == 0) {
-    *argt |= EX_BANG;
-  } else if (STRNICMP(attr, "buffer", len) == 0) {
-    *flags |= UC_BUFFER;
-  } else if (STRNICMP(attr, "register", len) == 0) {
-    *argt |= EX_REGSTR;
-  } else if (STRNICMP(attr, "keepscript", len) == 0) {
-    *argt |= EX_KEEPSCRIPT;
-  } else if (STRNICMP(attr, "bar", len) == 0) {
-    *argt |= EX_TRLBAR;
-  } else {
-    int i;
-    char *val = NULL;
-    size_t vallen = 0;
-    size_t attrlen = len;
-
-    // Look for the attribute name - which is the part before any '='
-    for (i = 0; i < (int)len; i++) {
-      if (attr[i] == '=') {
-        val = &attr[i + 1];
-        vallen = len - (size_t)i - 1;
-        attrlen = (size_t)i;
-        break;
-      }
-    }
-
-    if (STRNICMP(attr, "nargs", attrlen) == 0) {
-      if (vallen == 1) {
-        if (*val == '0') {
-          // Do nothing - this is the default;
-        } else if (*val == '1') {
-          *argt |= (EX_EXTRA | EX_NOSPC | EX_NEEDARG);
-        } else if (*val == '*') {
-          *argt |= EX_EXTRA;
-        } else if (*val == '?') {
-          *argt |= (EX_EXTRA | EX_NOSPC);
-        } else if (*val == '+') {
-          *argt |= (EX_EXTRA | EX_NEEDARG);
-        } else {
-          goto wrong_nargs;
-        }
-      } else {
-wrong_nargs:
-        emsg(_("E176: Invalid number of arguments"));
-        return FAIL;
-      }
-    } else if (STRNICMP(attr, "range", attrlen) == 0) {
-      *argt |= EX_RANGE;
-      if (vallen == 1 && *val == '%') {
-        *argt |= EX_DFLALL;
-      } else if (val != NULL) {
-        p = val;
-        if (*def >= 0) {
-two_count:
-          emsg(_("E177: Count cannot be specified twice"));
-          return FAIL;
-        }
-
-        *def = getdigits_long(&p, true, 0);
-        *argt |= EX_ZEROR;
-
-        if (p != val + vallen || vallen == 0) {
-invalid_count:
-          emsg(_("E178: Invalid default value for count"));
-          return FAIL;
-        }
-      }
-      // default for -range is using buffer lines
-      if (*addr_type_arg == ADDR_NONE) {
-        *addr_type_arg = ADDR_LINES;
-      }
-    } else if (STRNICMP(attr, "count", attrlen) == 0) {
-      *argt |= (EX_COUNT | EX_ZEROR | EX_RANGE);
-      // default for -count is using any number
-      if (*addr_type_arg == ADDR_NONE) {
-        *addr_type_arg = ADDR_OTHER;
-      }
-
-      if (val != NULL) {
-        p = val;
-        if (*def >= 0) {
-          goto two_count;
-        }
-
-        *def = getdigits_long(&p, true, 0);
-
-        if (p != val + vallen) {
-          goto invalid_count;
-        }
-      }
-
-      if (*def < 0) {
-        *def = 0;
-      }
-    } else if (STRNICMP(attr, "complete", attrlen) == 0) {
-      if (val == NULL) {
-        emsg(_("E179: argument required for -complete"));
-        return FAIL;
-      }
-
-      if (parse_compl_arg(val, (int)vallen, complp, argt, (char **)compl_arg)
-          == FAIL) {
-        return FAIL;
-      }
-    } else if (STRNICMP(attr, "addr", attrlen) == 0) {
-      *argt |= EX_RANGE;
-      if (val == NULL) {
-        emsg(_("E179: argument required for -addr"));
-        return FAIL;
-      }
-      if (parse_addr_type_arg(val, (int)vallen, addr_type_arg) == FAIL) {
-        return FAIL;
-      }
-      if (*addr_type_arg != ADDR_LINES) {
-        *argt |= EX_ZEROR;
-      }
-    } else {
-      char ch = attr[len];
-      attr[len] = '\0';
-      semsg(_("E181: Invalid attribute: %s"), attr);
-      attr[len] = ch;
-      return FAIL;
-    }
-  }
-
-  return OK;
-}
-
-static char e_complete_used_without_nargs[] = N_("E1208: -complete used without -nargs");
-
-/// ":command ..."
-static void ex_command(exarg_T *eap)
-{
-  char *name;
-  char *end;
-  char *p;
-  uint32_t argt = 0;
-  long def = -1;
-  int flags = 0;
-  int compl = EXPAND_NOTHING;
-  char *compl_arg = NULL;
-  cmd_addr_T addr_type_arg = ADDR_NONE;
-  int has_attr = (eap->arg[0] == '-');
-  size_t name_len;
-
-  p = eap->arg;
-
-  // Check for attributes
-  while (*p == '-') {
-    p++;
-    end = (char *)skiptowhite((char_u *)p);
-    if (uc_scan_attr(p, (size_t)(end - p), &argt, &def, &flags, &compl, (char_u **)&compl_arg,
-                     &addr_type_arg) == FAIL) {
-      return;
-    }
-    p = skipwhite(end);
-  }
-
-  // Get the name (if any) and skip to the following argument.
-  name = p;
-  end = uc_validate_name(name);
-  if (!end) {
-    emsg(_("E182: Invalid command name"));
-    return;
-  }
-  name_len = (size_t)(end - name);
-
-  // If there is nothing after the name, and no attributes were specified,
-  // we are listing commands
-  p = skipwhite(end);
-  if (!has_attr && ends_excmd(*p)) {
-    uc_list(name, name_len);
-  } else if (!ASCII_ISUPPER(*name)) {
-    emsg(_("E183: User defined commands must start with an uppercase letter"));
-  } else if (name_len <= 4 && STRNCMP(name, "Next", name_len) == 0) {
-    emsg(_("E841: Reserved name, cannot be used for user defined command"));
-  } else if (compl > 0 && (argt & EX_EXTRA) == 0) {
-    emsg(_(e_complete_used_without_nargs));
-  } else {
-    uc_add_command(name, name_len, p, argt, def, flags, compl, compl_arg, LUA_NOREF, LUA_NOREF,
-                   addr_type_arg, LUA_NOREF, eap->forceit);
-  }
-}
-
-/// ":comclear"
-/// Clear all user commands, global and for current buffer.
-void ex_comclear(exarg_T *eap)
-{
-  uc_clear(&ucmds);
-  uc_clear(&curbuf->b_ucmds);
-}
-
-void free_ucmd(ucmd_T *cmd)
-{
-  xfree(cmd->uc_name);
-  xfree(cmd->uc_rep);
-  xfree(cmd->uc_compl_arg);
-  NLUA_CLEAR_REF(cmd->uc_compl_luaref);
-  NLUA_CLEAR_REF(cmd->uc_luaref);
-  NLUA_CLEAR_REF(cmd->uc_preview_luaref);
-}
-
-/// Clear all user commands for "gap".
-void uc_clear(garray_T *gap)
-{
-  GA_DEEP_CLEAR(gap, ucmd_T, free_ucmd);
-}
-
-static void ex_delcommand(exarg_T *eap)
-{
-  int i = 0;
-  ucmd_T *cmd = NULL;
-  int res = -1;
-  garray_T *gap;
-  const char *arg = eap->arg;
-  bool buffer_only = false;
-
-  if (STRNCMP(arg, "-buffer", 7) == 0 && ascii_iswhite(arg[7])) {
-    buffer_only = true;
-    arg = skipwhite(arg + 7);
-  }
-
-  gap = &curbuf->b_ucmds;
-  for (;;) {
-    for (i = 0; i < gap->ga_len; i++) {
-      cmd = USER_CMD_GA(gap, i);
-      res = STRCMP(arg, cmd->uc_name);
-      if (res <= 0) {
-        break;
-      }
-    }
-    if (gap == &ucmds || res == 0 || buffer_only) {
-      break;
-    }
-    gap = &ucmds;
-  }
-
-  if (res != 0) {
-    semsg(_(buffer_only
-            ? e_no_such_user_defined_command_in_current_buffer_str
-            : e_no_such_user_defined_command_str),
-          arg);
-    return;
-  }
-
-  free_ucmd(cmd);
-
-  --gap->ga_len;
-
-  if (i < gap->ga_len) {
-    memmove(cmd, cmd + 1, (size_t)(gap->ga_len - i) * sizeof(ucmd_T));
-  }
-}
-
-/// Split a string by unescaped whitespace (space & tab), used for f-args on Lua commands callback.
-/// Similar to uc_split_args(), but does not allocate, add quotes, add commas and is an iterator.
-///
-/// @param[in]  arg String to split
-/// @param[in]  arglen Length of {arg}
-/// @param[inout] end Index of last character of previous iteration
-/// @param[out] buf Buffer to copy string into
-/// @param[out] len Length of string in {buf}
-///
-/// @return true if iteration is complete, else false
-bool uc_split_args_iter(const char *arg, size_t arglen, size_t *end, char *buf, size_t *len)
-{
-  if (!arglen) {
-    return true;
-  }
-
-  size_t pos = *end;
-  while (pos < arglen && ascii_iswhite(arg[pos])) {
-    pos++;
-  }
-
-  size_t l = 0;
-  for (; pos < arglen - 1; pos++) {
-    if (arg[pos] == '\\' && (arg[pos + 1] == '\\' || ascii_iswhite(arg[pos + 1]))) {
-      buf[l++] = arg[++pos];
-    } else {
-      buf[l++] = arg[pos];
-      if (ascii_iswhite(arg[pos + 1])) {
-        *end = pos + 1;
-        *len = l;
-        return false;
-      }
-    }
-  }
-
-  if (pos < arglen && !ascii_iswhite(arg[pos])) {
-    buf[l++] = arg[pos];
-  }
-
-  *len = l;
-  return true;
-}
-
-/// split and quote args for <f-args>
-static char *uc_split_args(char *arg, char **args, size_t *arglens, size_t argc, size_t *lenp)
-{
-  char *buf;
-  char *p;
-  char *q;
-  int len;
-
-  // Precalculate length
-  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;
-        }
-        len += 3;       // ","
-      } else {
-        const int charlen = utfc_ptr2len(p);
-
-        len += charlen;
-        p += charlen;
-      }
-    }
-  } 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;
-        }
-      }
-
-      if (i != argc - 1) {
-        len += 3;  // ","
-      }
-    }
-  }
-
-  buf = xmalloc((size_t)len + 1);
-
-  q = buf;
-  *q++ = '"';
-
-  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 = 0;
-
-  *lenp = (size_t)len;
-  return buf;
-}
-
-static size_t add_cmd_modifier(char *buf, char *mod_str, bool *multi_mods)
-{
-  size_t result = STRLEN(mod_str);
-  if (*multi_mods) {
-    result++;
-  }
-
-  if (buf != NULL) {
-    if (*multi_mods) {
-      STRCAT(buf, " ");
-    }
-    STRCAT(buf, mod_str);
-  }
-
-  *multi_mods = true;
-  return result;
-}
-
-/// Check for a <> code in a user command.
-///
-/// @param code       points to the '<'.  "len" the length of the <> (inclusive).
-/// @param buf        is where the result is to be added.
-/// @param cmd        the user command we're expanding
-/// @param eap        ex arguments
-/// @param split_buf  points to a buffer used for splitting, caller should free it.
-/// @param split_len  is the length of what "split_buf" contains.
-///
-/// @return           the length of the replacement, which has been added to "buf".
-///                   Return -1 if there was no match, and only the "<" has been copied.
-static size_t uc_check_code(char *code, size_t len, char *buf, ucmd_T *cmd, exarg_T *eap,
-                            char **split_buf, size_t *split_len)
-{
-  size_t result = 0;
-  char *p = code + 1;
-  size_t l = len - 2;
-  int quote = 0;
-  enum {
-    ct_ARGS,
-    ct_BANG,
-    ct_COUNT,
-    ct_LINE1,
-    ct_LINE2,
-    ct_RANGE,
-    ct_MODS,
-    ct_REGISTER,
-    ct_LT,
-    ct_NONE,
-  } type = ct_NONE;
-
-  if ((vim_strchr("qQfF", *p) != NULL) && p[1] == '-') {
-    quote = (*p == 'q' || *p == 'Q') ? 1 : 2;
-    p += 2;
-    l -= 2;
-  }
-
-  l++;
-  if (l <= 1) {
-    type = ct_NONE;
-  } else if (STRNICMP(p, "args>", l) == 0) {
-    type = ct_ARGS;
-  } else if (STRNICMP(p, "bang>", l) == 0) {
-    type = ct_BANG;
-  } else if (STRNICMP(p, "count>", l) == 0) {
-    type = ct_COUNT;
-  } else if (STRNICMP(p, "line1>", l) == 0) {
-    type = ct_LINE1;
-  } else if (STRNICMP(p, "line2>", l) == 0) {
-    type = ct_LINE2;
-  } else if (STRNICMP(p, "range>", l) == 0) {
-    type = ct_RANGE;
-  } else if (STRNICMP(p, "lt>", l) == 0) {
-    type = ct_LT;
-  } else if (STRNICMP(p, "reg>", l) == 0 || STRNICMP(p, "register>", l) == 0) {
-    type = ct_REGISTER;
-  } else if (STRNICMP(p, "mods>", l) == 0) {
-    type = ct_MODS;
-  }
-
-  switch (type) {
-  case ct_ARGS:
-    // Simple case first
-    if (*eap->arg == NUL) {
-      if (quote == 1) {
-        result = 2;
-        if (buf != NULL) {
-          STRCPY(buf, "''");
-        }
-      } else {
-        result = 0;
-      }
-      break;
-    }
-
-    /* When specified there is a single argument don't split it.
-     * Works for ":Cmd %" when % is "a b c". */
-    if ((eap->argt & EX_NOSPC) && quote == 2) {
-      quote = 1;
-    }
-
-    switch (quote) {
-    case 0:     // No quoting, no splitting
-      result = STRLEN(eap->arg);
-      if (buf != NULL) {
-        STRCPY(buf, eap->arg);
-      }
-      break;
-    case 1:     // Quote, but don't split
-      result = STRLEN(eap->arg) + 2;
-      for (p = eap->arg; *p; p++) {
-        if (*p == '\\' || *p == '"') {
-          result++;
-        }
-      }
-
-      if (buf != NULL) {
-        *buf++ = '"';
-        for (p = eap->arg; *p; p++) {
-          if (*p == '\\' || *p == '"') {
-            *buf++ = '\\';
-          }
-          *buf++ = *p;
-        }
-        *buf = '"';
-      }
-
-      break;
-    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, eap->args, eap->arglens, eap->argc, split_len);
-      }
-
-      result = *split_len;
-      if (buf != NULL && result != 0) {
-        STRCPY(buf, *split_buf);
-      }
-
-      break;
-    }
-    break;
-
-  case ct_BANG:
-    result = eap->forceit ? 1 : 0;
-    if (quote) {
-      result += 2;
-    }
-    if (buf != NULL) {
-      if (quote) {
-        *buf++ = '"';
-      }
-      if (eap->forceit) {
-        *buf++ = '!';
-      }
-      if (quote) {
-        *buf = '"';
-      }
-    }
-    break;
-
-  case ct_LINE1:
-  case ct_LINE2:
-  case ct_RANGE:
-  case ct_COUNT: {
-    char num_buf[20];
-    long num = (type == ct_LINE1) ? eap->line1 :
-               (type == ct_LINE2) ? eap->line2 :
-               (type == ct_RANGE) ? eap->addr_count :
-               (eap->addr_count > 0) ? eap->line2 : cmd->uc_def;
-    size_t num_len;
-
-    sprintf(num_buf, "%" PRId64, (int64_t)num);
-    num_len = STRLEN(num_buf);
-    result = num_len;
-
-    if (quote) {
-      result += 2;
-    }
-
-    if (buf != NULL) {
-      if (quote) {
-        *buf++ = '"';
-      }
-      STRCPY(buf, num_buf);
-      buf += num_len;
-      if (quote) {
-        *buf = '"';
-      }
-    }
-
-    break;
-  }
-
-  case ct_MODS:
-    result = uc_mods(buf, &cmdmod, quote);
-    break;
-
-  case ct_REGISTER:
-    result = eap->regname ? 1 : 0;
-    if (quote) {
-      result += 2;
-    }
-    if (buf != NULL) {
-      if (quote) {
-        *buf++ = '\'';
-      }
-      if (eap->regname) {
-        *buf++ = (char)eap->regname;
-      }
-      if (quote) {
-        *buf = '\'';
-      }
-    }
-    break;
-
-  case ct_LT:
-    result = 1;
-    if (buf != NULL) {
-      *buf = '<';
-    }
-    break;
-
-  default:
-    // Not recognized: just copy the '<' and return -1.
-    result = (size_t)-1;
-    if (buf != NULL) {
-      *buf = '<';
-    }
-    break;
-  }
-
-  return result;
-}
-
-/// Add modifiers from "cmod->cmod_split" to "buf".  Set "multi_mods" when one
-/// was added.
-///
-/// @return the number of bytes added
-size_t add_win_cmd_modifers(char *buf, const cmdmod_T *cmod, bool *multi_mods)
-{
-  size_t result = 0;
-
-  // :aboveleft and :leftabove
-  if (cmod->cmod_split & WSP_ABOVE) {
-    result += add_cmd_modifier(buf, "aboveleft", multi_mods);
-  }
-  // :belowright and :rightbelow
-  if (cmod->cmod_split & WSP_BELOW) {
-    result += add_cmd_modifier(buf, "belowright", multi_mods);
-  }
-  // :botright
-  if (cmod->cmod_split & WSP_BOT) {
-    result += add_cmd_modifier(buf, "botright", multi_mods);
-  }
-
-  // :tab
-  if (cmod->cmod_tab > 0) {
-    result += add_cmd_modifier(buf, "tab", multi_mods);
-  }
-  // :topleft
-  if (cmod->cmod_split & WSP_TOP) {
-    result += add_cmd_modifier(buf, "topleft", multi_mods);
-  }
-  // :vertical
-  if (cmod->cmod_split & WSP_VERT) {
-    result += add_cmd_modifier(buf, "vertical", multi_mods);
-  }
-  return result;
-}
-
-/// Generate text for the "cmod" command modifiers.
-/// If "buf" is NULL just return the length.
-size_t uc_mods(char *buf, const cmdmod_T *cmod, bool quote)
-{
-  size_t result = 0;
-  bool multi_mods = false;
-
-  typedef struct {
-    int flag;
-    char *name;
-  } mod_entry_T;
-  static mod_entry_T mod_entries[] = {
-    { CMOD_BROWSE, "browse" },
-    { CMOD_CONFIRM, "confirm" },
-    { CMOD_HIDE, "hide" },
-    { CMOD_KEEPALT, "keepalt" },
-    { CMOD_KEEPJUMPS, "keepjumps" },
-    { CMOD_KEEPMARKS, "keepmarks" },
-    { CMOD_KEEPPATTERNS, "keeppatterns" },
-    { CMOD_LOCKMARKS, "lockmarks" },
-    { CMOD_NOSWAPFILE, "noswapfile" },
-    { CMOD_UNSILENT, "unsilent" },
-    { CMOD_NOAUTOCMD, "noautocmd" },
-    { CMOD_SANDBOX, "sandbox" },
-  };
-
-  result = quote ? 2 : 0;
-  if (buf != NULL) {
-    if (quote) {
-      *buf++ = '"';
-    }
-    *buf = '\0';
-  }
-
-  // the modifiers that are simple flags
-  for (size_t i = 0; i < ARRAY_SIZE(mod_entries); i++) {
-    if (cmod->cmod_flags & mod_entries[i].flag) {
-      result += add_cmd_modifier(buf, mod_entries[i].name, &multi_mods);
-    }
-  }
-
-  // :silent
-  if (cmod->cmod_flags & CMOD_SILENT) {
-    result += add_cmd_modifier(buf,
-                               (cmod->cmod_flags & CMOD_ERRSILENT) ? "silent!" : "silent",
-                               &multi_mods);
-  }
-  // :verbose
-  if (cmod->cmod_verbose > 0) {
-    int verbose_value = cmod->cmod_verbose - 1;
-    if (verbose_value == 1) {
-      result += add_cmd_modifier(buf, "verbose", &multi_mods);
-    } else {
-      char verbose_buf[NUMBUFLEN];
-      snprintf(verbose_buf, NUMBUFLEN, "%dverbose", verbose_value);
-      result += add_cmd_modifier(buf, verbose_buf, &multi_mods);
-    }
-  }
-  // flags from cmod->cmod_split
-  result += add_win_cmd_modifers(buf, cmod, &multi_mods);
-
-  if (quote && buf != NULL) {
-    buf += result - 2;
-    *buf = '"';
-  }
-  return result;
-}
-
-static int do_ucmd(exarg_T *eap, bool preview)
-{
-  char *buf;
-  char *p;
-  char *q;
-
-  char *start;
-  char *end = NULL;
-  char *ksp;
-  size_t len, totlen;
-
-  size_t split_len = 0;
-  char *split_buf = NULL;
-  ucmd_T *cmd;
-
-  if (eap->cmdidx == CMD_USER) {
-    cmd = USER_CMD(eap->useridx);
-  } else {
-    cmd = USER_CMD_GA(&curbuf->b_ucmds, eap->useridx);
-  }
-
-  if (preview) {
-    assert(cmd->uc_preview_luaref > 0);
-    return nlua_do_ucmd(cmd, eap, true);
-  }
-
-  if (cmd->uc_luaref > 0) {
-    nlua_do_ucmd(cmd, eap, false);
-    return 0;
-  }
-
-  /*
-   * Replace <> in the command by the arguments.
-   * First round: "buf" is NULL, compute length, allocate "buf".
-   * Second round: copy result into "buf".
-   */
-  buf = NULL;
-  for (;;) {
-    p = (char *)cmd->uc_rep;        // source
-    q = buf;                // destination
-    totlen = 0;
-
-    for (;;) {
-      start = vim_strchr(p, '<');
-      if (start != NULL) {
-        end = vim_strchr(start + 1, '>');
-      }
-      if (buf != NULL) {
-        for (ksp = p; *ksp != NUL && (char_u)(*ksp) != K_SPECIAL; ksp++) {}
-        if ((char_u)(*ksp) == K_SPECIAL
-            && (start == NULL || ksp < start || end == NULL)
-            && ((char_u)ksp[1] == KS_SPECIAL && ksp[2] == KE_FILLER)) {
-          // K_SPECIAL has been put in the buffer as K_SPECIAL
-          // KS_SPECIAL KE_FILLER, like for mappings, but
-          // do_cmdline() doesn't handle that, so convert it back.
-          len = (size_t)(ksp - p);
-          if (len > 0) {
-            memmove(q, p, len);
-            q += len;
-          }
-          *q++ = (char)K_SPECIAL;
-          p = ksp + 3;
-          continue;
-        }
-      }
-
-      // break if no <item> is found
-      if (start == NULL || end == NULL) {
-        break;
-      }
-
-      // Include the '>'
-      ++end;
-
-      // Take everything up to the '<'
-      len = (size_t)(start - p);
-      if (buf == NULL) {
-        totlen += len;
-      } else {
-        memmove(q, p, len);
-        q += len;
-      }
-
-      len = uc_check_code(start, (size_t)(end - start), q, cmd, eap, &split_buf, &split_len);
-      if (len == (size_t)-1) {
-        // no match, continue after '<'
-        p = start + 1;
-        len = 1;
-      } else {
-        p = end;
-      }
-      if (buf == NULL) {
-        totlen += len;
-      } else {
-        q += len;
-      }
-    }
-    if (buf != NULL) {              // second time here, finished
-      STRCPY(q, p);
-      break;
-    }
-
-    totlen += STRLEN(p);            // Add on the trailing characters
-    buf = xmalloc(totlen + 1);
-  }
-
-  sctx_T save_current_sctx;
-  bool restore_current_sctx = false;
-  if ((cmd->uc_argt & EX_KEEPSCRIPT) == 0) {
-    restore_current_sctx = true;
-    save_current_sctx = current_sctx;
-    current_sctx.sc_sid = cmd->uc_script_ctx.sc_sid;
-  }
-  (void)do_cmdline(buf, eap->getline, eap->cookie,
-                   DOCMD_VERBOSE|DOCMD_NOWAIT|DOCMD_KEYTYPED);
-
-  // Careful: Do not use "cmd" here, it may have become invalid if a user
-  // command was added.
-  if (restore_current_sctx) {
-    current_sctx = save_current_sctx;
-  }
-  xfree(buf);
-  xfree(split_buf);
-
-  return 0;
-}
-
-static char *expand_user_command_name(int idx)
-{
-  return get_user_commands(NULL, idx - CMD_SIZE);
-}
-
-/// Function given to ExpandGeneric() to obtain the list of user address type names.
-char *get_user_cmd_addr_type(expand_T *xp, int idx)
-{
-  return addr_type_complete[idx].name;
-}
-
-/// Function given to ExpandGeneric() to obtain the list of user command names.
-char *get_user_commands(expand_T *xp FUNC_ATTR_UNUSED, int idx)
-  FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
-{
-  // In cmdwin, the alternative buffer should be used.
-  const buf_T *const buf = prevwin_curwin()->w_buffer;
-
-  if (idx < buf->b_ucmds.ga_len) {
-    return (char *)USER_CMD_GA(&buf->b_ucmds, idx)->uc_name;
-  }
-
-  idx -= buf->b_ucmds.ga_len;
-  if (idx < ucmds.ga_len) {
-    char *name = (char *)USER_CMD(idx)->uc_name;
-
-    for (int i = 0; i < buf->b_ucmds.ga_len; i++) {
-      if (STRCMP(name, USER_CMD_GA(&buf->b_ucmds, i)->uc_name) == 0) {
-        // global command is overruled by buffer-local one
-        return "";
-      }
-    }
-    return name;
-  }
-  return NULL;
-}
-
-/// Get the name of user command "idx".  "cmdidx" can be CMD_USER or
-/// CMD_USER_BUF.
-///
-/// @return  NULL if the command is not found.
-static char *get_user_command_name(int idx, int cmdidx)
-{
-  if (cmdidx == CMD_USER && idx < ucmds.ga_len) {
-    return (char *)USER_CMD(idx)->uc_name;
-  }
-  if (cmdidx == CMD_USER_BUF) {
-    // In cmdwin, the alternative buffer should be used.
-    const buf_T *const buf = prevwin_curwin()->w_buffer;
-
-    if (idx < buf->b_ucmds.ga_len) {
-      return (char *)USER_CMD_GA(&buf->b_ucmds, idx)->uc_name;
-    }
-  }
-  return NULL;
-}
-
-/// Function given to ExpandGeneric() to obtain the list of user command
-/// attributes.
-char *get_user_cmd_flags(expand_T *xp, int idx)
-{
-  static char *user_cmd_flags[] = { "addr",   "bang",     "bar",
-                                    "buffer", "complete", "count",
-                                    "nargs",  "range",    "register",
-                                    "keepscript" };
-
-  if (idx >= (int)ARRAY_SIZE(user_cmd_flags)) {
-    return NULL;
-  }
-  return user_cmd_flags[idx];
-}
-
-/// Function given to ExpandGeneric() to obtain the list of values for -nargs.
-char *get_user_cmd_nargs(expand_T *xp, int idx)
-{
-  static char *user_cmd_nargs[] = { "0", "1", "*", "?", "+" };
-
-  if (idx >= (int)ARRAY_SIZE(user_cmd_nargs)) {
-    return NULL;
-  }
-  return user_cmd_nargs[idx];
-}
-
-/// Function given to ExpandGeneric() to obtain the list of values for -complete.
-char *get_user_cmd_complete(expand_T *xp, int idx)
-{
-  if (idx >= (int)ARRAY_SIZE(command_complete)) {
-    return NULL;
-  }
-  char *cmd_compl = get_command_complete(idx);
-  if (cmd_compl == NULL) {
-    return "";
-  } else {
-    return cmd_compl;
-  }
-}
-
-/// Parse address type argument
-int parse_addr_type_arg(char *value, int vallen, cmd_addr_T *addr_type_arg)
-  FUNC_ATTR_NONNULL_ALL
-{
-  int i, a, b;
-
-  for (i = 0; addr_type_complete[i].expand != ADDR_NONE; i++) {
-    a = (int)STRLEN(addr_type_complete[i].name) == vallen;
-    b = STRNCMP(value, addr_type_complete[i].name, vallen) == 0;
-    if (a && b) {
-      *addr_type_arg = addr_type_complete[i].expand;
-      break;
-    }
-  }
-
-  if (addr_type_complete[i].expand == ADDR_NONE) {
-    char *err = value;
-
-    for (i = 0; err[i] != NUL && !ascii_iswhite(err[i]); i++) {}
-    err[i] = NUL;
-    semsg(_("E180: Invalid address type value: %s"), err);
-    return FAIL;
-  }
-
-  return OK;
-}
-
-/// Parse a completion argument "value[vallen]".
-/// The detected completion goes in "*complp", argument type in "*argt".
-/// When there is an argument, for function and user defined completion, it's
-/// copied to allocated memory and stored in "*compl_arg".
-///
-/// @return  FAIL if something is wrong.
-int parse_compl_arg(const char *value, int vallen, int *complp, uint32_t *argt, char **compl_arg)
-  FUNC_ATTR_NONNULL_ALL
-{
-  const char *arg = NULL;
-  size_t arglen = 0;
-  int i;
-  int valend = vallen;
-
-  // Look for any argument part - which is the part after any ','
-  for (i = 0; i < vallen; ++i) {
-    if (value[i] == ',') {
-      arg = (char *)&value[i + 1];
-      arglen = (size_t)(vallen - i - 1);
-      valend = i;
-      break;
-    }
-  }
-
-  for (i = 0; i < (int)ARRAY_SIZE(command_complete); i++) {
-    if (get_command_complete(i) == NULL) {
-      continue;
-    }
-    if ((int)STRLEN(command_complete[i]) == valend
-        && STRNCMP(value, command_complete[i], valend) == 0) {
-      *complp = i;
-      if (i == EXPAND_BUFFERS) {
-        *argt |= EX_BUFNAME;
-      } else if (i == EXPAND_DIRECTORIES || i == EXPAND_FILES) {
-        *argt |= EX_XFILE;
-      }
-      break;
-    }
-  }
-
-  if (i == (int)ARRAY_SIZE(command_complete)) {
-    semsg(_("E180: Invalid complete value: %s"), value);
-    return FAIL;
-  }
-
-  if (*complp != EXPAND_USER_DEFINED && *complp != EXPAND_USER_LIST
-      && arg != NULL) {
-    emsg(_("E468: Completion argument only allowed for custom completion"));
-    return FAIL;
-  }
-
-  if ((*complp == EXPAND_USER_DEFINED || *complp == EXPAND_USER_LIST)
-      && arg == NULL) {
-    emsg(_("E467: Custom completion requires a function argument"));
-    return FAIL;
-  }
-
-  if (arg != NULL) {
-    *compl_arg = xstrnsave(arg, arglen);
-  }
-  return OK;
-}
-
-int cmdcomplete_str_to_type(const char *complete_str)
-{
-  for (int i = 0; i < (int)(ARRAY_SIZE(command_complete)); i++) {
-    char *cmd_compl = get_command_complete(i);
-    if (cmd_compl == NULL) {
-      continue;
-    }
-    if (strcmp(complete_str, command_complete[i]) == 0) {
-      return i;
-    }
-  }
-
-  return EXPAND_NOTHING;
-}
-
 static void ex_colorscheme(exarg_T *eap)
 {
   if (*eap->arg == NUL) {
@@ -10033,91 +8408,6 @@ static void ex_terminal(exarg_T *eap)
   do_cmdline_cmd(ex_cmd);
 }
 
-/// Gets a map of maps describing user-commands defined for buffer `buf` or
-/// defined globally if `buf` is NULL.
-///
-/// @param buf  Buffer to inspect, or NULL to get global commands.
-///
-/// @return Map of maps describing commands
-Dictionary commands_array(buf_T *buf)
-{
-  Dictionary rv = ARRAY_DICT_INIT;
-  char str[20];
-  garray_T *gap = (buf == NULL) ? &ucmds : &buf->b_ucmds;
-
-  for (int i = 0; i < gap->ga_len; i++) {
-    char arg[2] = { 0, 0 };
-    Dictionary d = ARRAY_DICT_INIT;
-    ucmd_T *cmd = USER_CMD_GA(gap, i);
-
-    PUT(d, "name", STRING_OBJ(cstr_to_string((char *)cmd->uc_name)));
-    PUT(d, "definition", STRING_OBJ(cstr_to_string((char *)cmd->uc_rep)));
-    PUT(d, "script_id", INTEGER_OBJ(cmd->uc_script_ctx.sc_sid));
-    PUT(d, "bang", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_BANG)));
-    PUT(d, "bar", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_TRLBAR)));
-    PUT(d, "register", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_REGSTR)));
-    PUT(d, "keepscript", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_KEEPSCRIPT)));
-    PUT(d, "preview", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_PREVIEW)));
-
-    switch (cmd->uc_argt & (EX_EXTRA | EX_NOSPC | EX_NEEDARG)) {
-    case 0:
-      arg[0] = '0'; break;
-    case (EX_EXTRA):
-      arg[0] = '*'; break;
-    case (EX_EXTRA | EX_NOSPC):
-      arg[0] = '?'; break;
-    case (EX_EXTRA | EX_NEEDARG):
-      arg[0] = '+'; break;
-    case (EX_EXTRA | EX_NOSPC | EX_NEEDARG):
-      arg[0] = '1'; break;
-    }
-    PUT(d, "nargs", STRING_OBJ(cstr_to_string(arg)));
-
-    char *cmd_compl = get_command_complete(cmd->uc_compl);
-    PUT(d, "complete", (cmd_compl == NULL
-                        ? NIL : STRING_OBJ(cstr_to_string(cmd_compl))));
-    PUT(d, "complete_arg", cmd->uc_compl_arg == NULL
-        ? NIL : STRING_OBJ(cstr_to_string((char *)cmd->uc_compl_arg)));
-
-    Object obj = NIL;
-    if (cmd->uc_argt & EX_COUNT) {
-      if (cmd->uc_def >= 0) {
-        snprintf(str, sizeof(str), "%" PRId64, (int64_t)cmd->uc_def);
-        obj = STRING_OBJ(cstr_to_string(str));    // -count=N
-      } else {
-        obj = STRING_OBJ(cstr_to_string("0"));    // -count
-      }
-    }
-    PUT(d, "count", obj);
-
-    obj = NIL;
-    if (cmd->uc_argt & EX_RANGE) {
-      if (cmd->uc_argt & EX_DFLALL) {
-        obj = STRING_OBJ(cstr_to_string("%"));    // -range=%
-      } else if (cmd->uc_def >= 0) {
-        snprintf(str, sizeof(str), "%" PRId64, (int64_t)cmd->uc_def);
-        obj = STRING_OBJ(cstr_to_string(str));    // -range=N
-      } else {
-        obj = STRING_OBJ(cstr_to_string("."));    // -range
-      }
-    }
-    PUT(d, "range", obj);
-
-    obj = NIL;
-    for (int j = 0; addr_type_complete[j].expand != ADDR_NONE; j++) {
-      if (addr_type_complete[j].expand != ADDR_LINES
-          && addr_type_complete[j].expand == cmd->uc_addr_type) {
-        obj = STRING_OBJ(cstr_to_string(addr_type_complete[j].name));
-        break;
-      }
-    }
-    PUT(d, "addr", obj);
-
-    PUT(rv, (char *)cmd->uc_name, DICTIONARY_OBJ(d));
-  }
-  return rv;
-}
-
 void verify_command(char *cmd)
 {
   if (strcmp("smile", cmd)) {
diff --git a/src/nvim/ex_docmd.h b/src/nvim/ex_docmd.h
index ddb25c53e4..283501cf76 100644
--- a/src/nvim/ex_docmd.h
+++ b/src/nvim/ex_docmd.h
@@ -33,27 +33,6 @@ typedef struct {
   tasave_T tabuf;
 } save_state_T;
 
-typedef struct ucmd {
-  char_u *uc_name;              // The command name
-  uint32_t uc_argt;             // The argument type
-  char_u *uc_rep;               // The command's replacement string
-  long uc_def;                  // The default value for a range/count
-  int uc_compl;                 // completion type
-  cmd_addr_T uc_addr_type;      // The command's address type
-  sctx_T uc_script_ctx;         // SCTX where the command was defined
-  char_u *uc_compl_arg;         // completion argument if any
-  LuaRef uc_compl_luaref;       // Reference to Lua completion function
-  LuaRef uc_preview_luaref;     // Reference to Lua preview function
-  LuaRef uc_luaref;             // Reference to Lua function
-} ucmd_T;
-
-#define UC_BUFFER       1       // -buffer: local to current buffer
-
-extern garray_T ucmds;
-
-#define USER_CMD(i) (&((ucmd_T *)(ucmds.ga_data))[i])
-#define USER_CMD_GA(gap, i) (&((ucmd_T *)((gap)->ga_data))[i])
-
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "ex_docmd.h.generated.h"
 #endif
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index 28ff0cbd59..2b2889d4d6 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -17,6 +17,7 @@
 #include "nvim/cursor.h"
 #include "nvim/edit.h"
 #include "nvim/event/loop.h"
+#include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
 #include "nvim/garray.h"
 #include "nvim/getchar.h"
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 197a209e97..661dbfc4c2 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -21,7 +21,6 @@
 #include "nvim/event/loop.h"
 #include "nvim/event/time.h"
 #include "nvim/ex_cmds2.h"
-#include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
 #include "nvim/extmark.h"
 #include "nvim/func_attr.h"
@@ -40,6 +39,7 @@
 #include "nvim/profile.h"
 #include "nvim/screen.h"
 #include "nvim/undo.h"
+#include "nvim/usercmd.h"
 #include "nvim/version.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
diff --git a/src/nvim/lua/executor.h b/src/nvim/lua/executor.h
index e96494ec5a..2afbbebfe7 100644
--- a/src/nvim/lua/executor.h
+++ b/src/nvim/lua/executor.h
@@ -8,9 +8,9 @@
 #include "nvim/assert.h"
 #include "nvim/eval/typval.h"
 #include "nvim/ex_cmds_defs.h"
-#include "nvim/ex_docmd.h"
 #include "nvim/func_attr.h"
 #include "nvim/lua/converter.h"
+#include "nvim/usercmd.h"
 
 // Generated by msgpack-gen.lua
 void nlua_add_api_functions(lua_State *lstate) REAL_FATTR_NONNULL_ALL;
diff --git a/src/nvim/usercmd.c b/src/nvim/usercmd.c
new file mode 100644
index 0000000000..9561f9baff
--- /dev/null
+++ b/src/nvim/usercmd.c
@@ -0,0 +1,1740 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
+// usercmd.c: User defined command support
+
+#include <assert.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "nvim/api/private/helpers.h"
+#include "nvim/ascii.h"
+#include "nvim/charset.h"
+#include "nvim/ex_docmd.h"
+#include "nvim/garray.h"
+#include "nvim/lua/executor.h"
+#include "nvim/os/input.h"
+#include "nvim/usercmd.h"
+#include "nvim/window.h"
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "usercmd.c.generated.h"
+#endif
+
+garray_T ucmds = { 0, 0, sizeof(ucmd_T), 4, NULL };
+
+static char e_complete_used_without_nargs[]
+  = N_("E1208: -complete used without -nargs");
+static char e_no_such_user_defined_command_str[]
+  = N_("E184: No such user-defined command: %s");
+static char e_no_such_user_defined_command_in_current_buffer_str[]
+  = N_("E1237: No such user-defined command in current buffer: %s");
+
+/// List of names for completion for ":command" with the EXPAND_ flag.
+/// Must be alphabetical for completion.
+static const char *command_complete[] =
+{
+  [EXPAND_ARGLIST] = "arglist",
+  [EXPAND_AUGROUP] = "augroup",
+  [EXPAND_BEHAVE] = "behave",
+  [EXPAND_BUFFERS] = "buffer",
+  [EXPAND_CHECKHEALTH] = "checkhealth",
+  [EXPAND_COLORS] = "color",
+  [EXPAND_COMMANDS] = "command",
+  [EXPAND_COMPILER] = "compiler",
+  [EXPAND_CSCOPE] = "cscope",
+  [EXPAND_USER_DEFINED] = "custom",
+  [EXPAND_USER_LIST] = "customlist",
+  [EXPAND_USER_LUA] = "<Lua function>",
+  [EXPAND_DIFF_BUFFERS] = "diff_buffer",
+  [EXPAND_DIRECTORIES] = "dir",
+  [EXPAND_ENV_VARS] = "environment",
+  [EXPAND_EVENTS] = "event",
+  [EXPAND_EXPRESSION] = "expression",
+  [EXPAND_FILES] = "file",
+  [EXPAND_FILES_IN_PATH] = "file_in_path",
+  [EXPAND_FILETYPE] = "filetype",
+  [EXPAND_FUNCTIONS] = "function",
+  [EXPAND_HELP] = "help",
+  [EXPAND_HIGHLIGHT] = "highlight",
+  [EXPAND_HISTORY] = "history",
+#ifdef HAVE_WORKING_LIBINTL
+  [EXPAND_LOCALES] = "locale",
+#endif
+  [EXPAND_LUA] = "lua",
+  [EXPAND_MAPCLEAR] = "mapclear",
+  [EXPAND_MAPPINGS] = "mapping",
+  [EXPAND_MENUS] = "menu",
+  [EXPAND_MESSAGES] = "messages",
+  [EXPAND_OWNSYNTAX] = "syntax",
+  [EXPAND_SYNTIME] = "syntime",
+  [EXPAND_SETTINGS] = "option",
+  [EXPAND_PACKADD] = "packadd",
+  [EXPAND_SHELLCMD] = "shellcmd",
+  [EXPAND_SIGN] = "sign",
+  [EXPAND_TAGS] = "tag",
+  [EXPAND_TAGS_LISTFILES] = "tag_listfiles",
+  [EXPAND_USER] = "user",
+  [EXPAND_USER_VARS] = "var",
+};
+
+/// List of names of address types.  Must be alphabetical for completion.
+static struct {
+  cmd_addr_T expand;
+  char *name;
+  char *shortname;
+} addr_type_complete[] =
+{
+  { ADDR_ARGUMENTS, "arguments", "arg" },
+  { ADDR_LINES, "lines", "line" },
+  { ADDR_LOADED_BUFFERS, "loaded_buffers", "load" },
+  { ADDR_TABS, "tabs", "tab" },
+  { ADDR_BUFFERS, "buffers", "buf" },
+  { ADDR_WINDOWS, "windows", "win" },
+  { ADDR_QUICKFIX, "quickfix", "qf" },
+  { ADDR_OTHER, "other", "?" },
+  { ADDR_NONE, NULL, NULL }
+};
+
+/// Search for a user command that matches "eap->cmd".
+/// Return cmdidx in "eap->cmdidx", flags in "eap->argt", idx in "eap->useridx".
+/// Return a pointer to just after the command.
+/// Return NULL if there is no matching command.
+///
+/// @param *p      end of the command (possibly including count)
+/// @param full    set to TRUE for a full match
+/// @param xp      used for completion, NULL otherwise
+/// @param complp  completion flags or NULL
+char *find_ucmd(exarg_T *eap, char *p, int *full, expand_T *xp, int *complp)
+{
+  int len = (int)(p - eap->cmd);
+  int j, k, matchlen = 0;
+  ucmd_T *uc;
+  bool found = false;
+  bool possible = false;
+  char *cp, *np;             // Point into typed cmd and test name
+  garray_T *gap;
+  bool amb_local = false;            // Found ambiguous buffer-local command,
+                                     // only full match global is accepted.
+
+  // Look for buffer-local user commands first, then global ones.
+  gap = &prevwin_curwin()->w_buffer->b_ucmds;
+  for (;;) {
+    for (j = 0; j < gap->ga_len; j++) {
+      uc = USER_CMD_GA(gap, j);
+      cp = eap->cmd;
+      np = (char *)uc->uc_name;
+      k = 0;
+      while (k < len && *np != NUL && *cp++ == *np++) {
+        k++;
+      }
+      if (k == len || (*np == NUL && ascii_isdigit(eap->cmd[k]))) {
+        // If finding a second match, the command is ambiguous.  But
+        // not if a buffer-local command wasn't a full match and a
+        // global command is a full match.
+        if (k == len && found && *np != NUL) {
+          if (gap == &ucmds) {
+            return NULL;
+          }
+          amb_local = true;
+        }
+
+        if (!found || (k == len && *np == NUL)) {
+          // If we matched up to a digit, then there could
+          // be another command including the digit that we
+          // should use instead.
+          if (k == len) {
+            found = true;
+          } else {
+            possible = true;
+          }
+
+          if (gap == &ucmds) {
+            eap->cmdidx = CMD_USER;
+          } else {
+            eap->cmdidx = CMD_USER_BUF;
+          }
+          eap->argt = uc->uc_argt;
+          eap->useridx = j;
+          eap->addr_type = uc->uc_addr_type;
+
+          if (complp != NULL) {
+            *complp = uc->uc_compl;
+          }
+          if (xp != NULL) {
+            xp->xp_luaref = uc->uc_compl_luaref;
+            xp->xp_arg = (char *)uc->uc_compl_arg;
+            xp->xp_script_ctx = uc->uc_script_ctx;
+            xp->xp_script_ctx.sc_lnum += sourcing_lnum;
+          }
+          // Do not search for further abbreviations
+          // if this is an exact match.
+          matchlen = k;
+          if (k == len && *np == NUL) {
+            if (full != NULL) {
+              *full = true;
+            }
+            amb_local = false;
+            break;
+          }
+        }
+      }
+    }
+
+    // Stop if we found a full match or searched all.
+    if (j < gap->ga_len || gap == &ucmds) {
+      break;
+    }
+    gap = &ucmds;
+  }
+
+  // Only found ambiguous matches.
+  if (amb_local) {
+    if (xp != NULL) {
+      xp->xp_context = EXPAND_UNSUCCESSFUL;
+    }
+    return NULL;
+  }
+
+  // The match we found may be followed immediately by a number.  Move "p"
+  // back to point to it.
+  if (found || possible) {
+    return p + (matchlen - len);
+  }
+  return p;
+}
+
+const char *set_context_in_user_cmd(expand_T *xp, const char *arg_in)
+{
+  const char *arg = arg_in;
+  const char *p;
+
+  // Check for attributes
+  while (*arg == '-') {
+    arg++;  // Skip "-".
+    p = (const char *)skiptowhite((const char_u *)arg);
+    if (*p == NUL) {
+      // Cursor is still in the attribute.
+      p = strchr(arg, '=');
+      if (p == NULL) {
+        // No "=", so complete attribute names.
+        xp->xp_context = EXPAND_USER_CMD_FLAGS;
+        xp->xp_pattern = (char *)arg;
+        return NULL;
+      }
+
+      // For the -complete, -nargs and -addr attributes, we complete
+      // their arguments as well.
+      if (STRNICMP(arg, "complete", p - arg) == 0) {
+        xp->xp_context = EXPAND_USER_COMPLETE;
+        xp->xp_pattern = (char *)p + 1;
+        return NULL;
+      } else if (STRNICMP(arg, "nargs", p - arg) == 0) {
+        xp->xp_context = EXPAND_USER_NARGS;
+        xp->xp_pattern = (char *)p + 1;
+        return NULL;
+      } else if (STRNICMP(arg, "addr", p - arg) == 0) {
+        xp->xp_context = EXPAND_USER_ADDR_TYPE;
+        xp->xp_pattern = (char *)p + 1;
+        return NULL;
+      }
+      return NULL;
+    }
+    arg = (const char *)skipwhite(p);
+  }
+
+  // After the attributes comes the new command name.
+  p = (const char *)skiptowhite((const char_u *)arg);
+  if (*p == NUL) {
+    xp->xp_context = EXPAND_USER_COMMANDS;
+    xp->xp_pattern = (char *)arg;
+    return NULL;
+  }
+
+  // And finally comes a normal command.
+  return (const char *)skipwhite(p);
+}
+
+char *expand_user_command_name(int idx)
+{
+  return get_user_commands(NULL, idx - CMD_SIZE);
+}
+
+/// Function given to ExpandGeneric() to obtain the list of user command names.
+char *get_user_commands(expand_T *xp FUNC_ATTR_UNUSED, int idx)
+  FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  // In cmdwin, the alternative buffer should be used.
+  const buf_T *const buf = prevwin_curwin()->w_buffer;
+
+  if (idx < buf->b_ucmds.ga_len) {
+    return (char *)USER_CMD_GA(&buf->b_ucmds, idx)->uc_name;
+  }
+
+  idx -= buf->b_ucmds.ga_len;
+  if (idx < ucmds.ga_len) {
+    char *name = (char *)USER_CMD(idx)->uc_name;
+
+    for (int i = 0; i < buf->b_ucmds.ga_len; i++) {
+      if (STRCMP(name, USER_CMD_GA(&buf->b_ucmds, i)->uc_name) == 0) {
+        // global command is overruled by buffer-local one
+        return "";
+      }
+    }
+    return name;
+  }
+  return NULL;
+}
+
+/// Get the name of user command "idx".  "cmdidx" can be CMD_USER or
+/// CMD_USER_BUF.
+///
+/// @return  NULL if the command is not found.
+char *get_user_command_name(int idx, int cmdidx)
+{
+  if (cmdidx == CMD_USER && idx < ucmds.ga_len) {
+    return (char *)USER_CMD(idx)->uc_name;
+  }
+  if (cmdidx == CMD_USER_BUF) {
+    // In cmdwin, the alternative buffer should be used.
+    const buf_T *const buf = prevwin_curwin()->w_buffer;
+
+    if (idx < buf->b_ucmds.ga_len) {
+      return (char *)USER_CMD_GA(&buf->b_ucmds, idx)->uc_name;
+    }
+  }
+  return NULL;
+}
+
+/// Function given to ExpandGeneric() to obtain the list of user address type names.
+char *get_user_cmd_addr_type(expand_T *xp, int idx)
+{
+  return addr_type_complete[idx].name;
+}
+
+/// Function given to ExpandGeneric() to obtain the list of user command
+/// attributes.
+char *get_user_cmd_flags(expand_T *xp, int idx)
+{
+  static char *user_cmd_flags[] = { "addr",   "bang",     "bar",
+                                    "buffer", "complete", "count",
+                                    "nargs",  "range",    "register",
+                                    "keepscript" };
+
+  if (idx >= (int)ARRAY_SIZE(user_cmd_flags)) {
+    return NULL;
+  }
+  return user_cmd_flags[idx];
+}
+
+/// Function given to ExpandGeneric() to obtain the list of values for -nargs.
+char *get_user_cmd_nargs(expand_T *xp, int idx)
+{
+  static char *user_cmd_nargs[] = { "0", "1", "*", "?", "+" };
+
+  if (idx >= (int)ARRAY_SIZE(user_cmd_nargs)) {
+    return NULL;
+  }
+  return user_cmd_nargs[idx];
+}
+
+static char *get_command_complete(int arg)
+{
+  if (arg >= (int)(ARRAY_SIZE(command_complete))) {
+    return NULL;
+  } else {
+    return (char *)command_complete[arg];
+  }
+}
+
+/// Function given to ExpandGeneric() to obtain the list of values for -complete.
+char *get_user_cmd_complete(expand_T *xp, int idx)
+{
+  if (idx >= (int)ARRAY_SIZE(command_complete)) {
+    return NULL;
+  }
+  char *cmd_compl = get_command_complete(idx);
+  if (cmd_compl == NULL) {
+    return "";
+  } else {
+    return cmd_compl;
+  }
+}
+
+int cmdcomplete_str_to_type(const char *complete_str)
+{
+  for (int i = 0; i < (int)(ARRAY_SIZE(command_complete)); i++) {
+    char *cmd_compl = get_command_complete(i);
+    if (cmd_compl == NULL) {
+      continue;
+    }
+    if (strcmp(complete_str, command_complete[i]) == 0) {
+      return i;
+    }
+  }
+
+  return EXPAND_NOTHING;
+}
+
+static void uc_list(char *name, size_t name_len)
+{
+  int i, j;
+  bool found = false;
+  ucmd_T *cmd;
+  uint32_t a;
+
+  // In cmdwin, the alternative buffer should be used.
+  const garray_T *gap = &prevwin_curwin()->w_buffer->b_ucmds;
+  for (;;) {
+    for (i = 0; i < gap->ga_len; i++) {
+      cmd = USER_CMD_GA(gap, i);
+      a = cmd->uc_argt;
+
+      // Skip commands which don't match the requested prefix and
+      // commands filtered out.
+      if (STRNCMP(name, cmd->uc_name, name_len) != 0
+          || message_filtered(cmd->uc_name)) {
+        continue;
+      }
+
+      // Put out the title first time
+      if (!found) {
+        msg_puts_title(_("\n    Name              Args Address "
+                         "Complete    Definition"));
+      }
+      found = true;
+      msg_putchar('\n');
+      if (got_int) {
+        break;
+      }
+
+      // Special cases
+      int len = 4;
+      if (a & EX_BANG) {
+        msg_putchar('!');
+        len--;
+      }
+      if (a & EX_REGSTR) {
+        msg_putchar('"');
+        len--;
+      }
+      if (gap != &ucmds) {
+        msg_putchar('b');
+        len--;
+      }
+      if (a & EX_TRLBAR) {
+        msg_putchar('|');
+        len--;
+      }
+      while (len-- > 0) {
+        msg_putchar(' ');
+      }
+
+      msg_outtrans_attr(cmd->uc_name, HL_ATTR(HLF_D));
+      len = (int)STRLEN(cmd->uc_name) + 4;
+
+      do {
+        msg_putchar(' ');
+        len++;
+      } while (len < 22);
+
+      // "over" is how much longer the name is than the column width for
+      // the name, we'll try to align what comes after.
+      const int over = len - 22;
+      len = 0;
+
+      // Arguments
+      switch (a & (EX_EXTRA | EX_NOSPC | EX_NEEDARG)) {
+      case 0:
+        IObuff[len++] = '0';
+        break;
+      case (EX_EXTRA):
+        IObuff[len++] = '*';
+        break;
+      case (EX_EXTRA | EX_NOSPC):
+        IObuff[len++] = '?';
+        break;
+      case (EX_EXTRA | EX_NEEDARG):
+        IObuff[len++] = '+';
+        break;
+      case (EX_EXTRA | EX_NOSPC | EX_NEEDARG):
+        IObuff[len++] = '1';
+        break;
+      }
+
+      do {
+        IObuff[len++] = ' ';
+      } while (len < 5 - over);
+
+      // Address / Range
+      if (a & (EX_RANGE | EX_COUNT)) {
+        if (a & EX_COUNT) {
+          // -count=N
+          snprintf((char *)IObuff + len, IOSIZE, "%" PRId64 "c",
+                   (int64_t)cmd->uc_def);
+          len += (int)STRLEN(IObuff + len);
+        } else if (a & EX_DFLALL) {
+          IObuff[len++] = '%';
+        } else if (cmd->uc_def >= 0) {
+          // -range=N
+          snprintf((char *)IObuff + len, IOSIZE, "%" PRId64 "",
+                   (int64_t)cmd->uc_def);
+          len += (int)STRLEN(IObuff + len);
+        } else {
+          IObuff[len++] = '.';
+        }
+      }
+
+      do {
+        IObuff[len++] = ' ';
+      } while (len < 8 - over);
+
+      // Address Type
+      for (j = 0; addr_type_complete[j].expand != ADDR_NONE; j++) {
+        if (addr_type_complete[j].expand != ADDR_LINES
+            && addr_type_complete[j].expand == cmd->uc_addr_type) {
+          STRCPY(IObuff + len, addr_type_complete[j].shortname);
+          len += (int)STRLEN(IObuff + len);
+          break;
+        }
+      }
+
+      do {
+        IObuff[len++] = ' ';
+      } while (len < 13 - over);
+
+      // Completion
+      char *cmd_compl = get_command_complete(cmd->uc_compl);
+      if (cmd_compl != NULL) {
+        STRCPY(IObuff + len, get_command_complete(cmd->uc_compl));
+        len += (int)STRLEN(IObuff + len);
+      }
+
+      do {
+        IObuff[len++] = ' ';
+      } while (len < 25 - over);
+
+      IObuff[len] = '\0';
+      msg_outtrans((char *)IObuff);
+
+      if (cmd->uc_luaref != LUA_NOREF) {
+        char *fn = nlua_funcref_str(cmd->uc_luaref);
+        msg_puts_attr(fn, HL_ATTR(HLF_8));
+        xfree(fn);
+        // put the description on a new line
+        if (*cmd->uc_rep != NUL) {
+          msg_puts("\n                                               ");
+        }
+      }
+
+      msg_outtrans_special(cmd->uc_rep, false,
+                           name_len == 0 ? Columns - 47 : 0);
+      if (p_verbose > 0) {
+        last_set_msg(cmd->uc_script_ctx);
+      }
+      line_breakcheck();
+      if (got_int) {
+        break;
+      }
+    }
+    if (gap == &ucmds || i < gap->ga_len) {
+      break;
+    }
+    gap = &ucmds;
+  }
+
+  if (!found) {
+    msg(_("No user-defined commands found"));
+  }
+}
+
+/// Parse address type argument
+int parse_addr_type_arg(char *value, int vallen, cmd_addr_T *addr_type_arg)
+  FUNC_ATTR_NONNULL_ALL
+{
+  int i, a, b;
+
+  for (i = 0; addr_type_complete[i].expand != ADDR_NONE; i++) {
+    a = (int)STRLEN(addr_type_complete[i].name) == vallen;
+    b = STRNCMP(value, addr_type_complete[i].name, vallen) == 0;
+    if (a && b) {
+      *addr_type_arg = addr_type_complete[i].expand;
+      break;
+    }
+  }
+
+  if (addr_type_complete[i].expand == ADDR_NONE) {
+    char *err = value;
+
+    for (i = 0; err[i] != NUL && !ascii_iswhite(err[i]); i++) {}
+    err[i] = NUL;
+    semsg(_("E180: Invalid address type value: %s"), err);
+    return FAIL;
+  }
+
+  return OK;
+}
+
+/// Parse a completion argument "value[vallen]".
+/// The detected completion goes in "*complp", argument type in "*argt".
+/// When there is an argument, for function and user defined completion, it's
+/// copied to allocated memory and stored in "*compl_arg".
+///
+/// @return  FAIL if something is wrong.
+int parse_compl_arg(const char *value, int vallen, int *complp, uint32_t *argt, char **compl_arg)
+  FUNC_ATTR_NONNULL_ALL
+{
+  const char *arg = NULL;
+  size_t arglen = 0;
+  int i;
+  int valend = vallen;
+
+  // Look for any argument part - which is the part after any ','
+  for (i = 0; i < vallen; i++) {
+    if (value[i] == ',') {
+      arg = (char *)&value[i + 1];
+      arglen = (size_t)(vallen - i - 1);
+      valend = i;
+      break;
+    }
+  }
+
+  for (i = 0; i < (int)ARRAY_SIZE(command_complete); i++) {
+    if (get_command_complete(i) == NULL) {
+      continue;
+    }
+    if ((int)STRLEN(command_complete[i]) == valend
+        && STRNCMP(value, command_complete[i], valend) == 0) {
+      *complp = i;
+      if (i == EXPAND_BUFFERS) {
+        *argt |= EX_BUFNAME;
+      } else if (i == EXPAND_DIRECTORIES || i == EXPAND_FILES) {
+        *argt |= EX_XFILE;
+      }
+      break;
+    }
+  }
+
+  if (i == (int)ARRAY_SIZE(command_complete)) {
+    semsg(_("E180: Invalid complete value: %s"), value);
+    return FAIL;
+  }
+
+  if (*complp != EXPAND_USER_DEFINED && *complp != EXPAND_USER_LIST
+      && arg != NULL) {
+    emsg(_("E468: Completion argument only allowed for custom completion"));
+    return FAIL;
+  }
+
+  if ((*complp == EXPAND_USER_DEFINED || *complp == EXPAND_USER_LIST)
+      && arg == NULL) {
+    emsg(_("E467: Custom completion requires a function argument"));
+    return FAIL;
+  }
+
+  if (arg != NULL) {
+    *compl_arg = xstrnsave(arg, arglen);
+  }
+  return OK;
+}
+
+static int uc_scan_attr(char *attr, size_t len, uint32_t *argt, long *def, int *flags, int *complp,
+                        char_u **compl_arg, cmd_addr_T *addr_type_arg)
+  FUNC_ATTR_NONNULL_ALL
+{
+  char *p;
+
+  if (len == 0) {
+    emsg(_("E175: No attribute specified"));
+    return FAIL;
+  }
+
+  // First, try the simple attributes (no arguments)
+  if (STRNICMP(attr, "bang", len) == 0) {
+    *argt |= EX_BANG;
+  } else if (STRNICMP(attr, "buffer", len) == 0) {
+    *flags |= UC_BUFFER;
+  } else if (STRNICMP(attr, "register", len) == 0) {
+    *argt |= EX_REGSTR;
+  } else if (STRNICMP(attr, "keepscript", len) == 0) {
+    *argt |= EX_KEEPSCRIPT;
+  } else if (STRNICMP(attr, "bar", len) == 0) {
+    *argt |= EX_TRLBAR;
+  } else {
+    int i;
+    char *val = NULL;
+    size_t vallen = 0;
+    size_t attrlen = len;
+
+    // Look for the attribute name - which is the part before any '='
+    for (i = 0; i < (int)len; i++) {
+      if (attr[i] == '=') {
+        val = &attr[i + 1];
+        vallen = len - (size_t)i - 1;
+        attrlen = (size_t)i;
+        break;
+      }
+    }
+
+    if (STRNICMP(attr, "nargs", attrlen) == 0) {
+      if (vallen == 1) {
+        if (*val == '0') {
+          // Do nothing - this is the default;
+        } else if (*val == '1') {
+          *argt |= (EX_EXTRA | EX_NOSPC | EX_NEEDARG);
+        } else if (*val == '*') {
+          *argt |= EX_EXTRA;
+        } else if (*val == '?') {
+          *argt |= (EX_EXTRA | EX_NOSPC);
+        } else if (*val == '+') {
+          *argt |= (EX_EXTRA | EX_NEEDARG);
+        } else {
+          goto wrong_nargs;
+        }
+      } else {
+wrong_nargs:
+        emsg(_("E176: Invalid number of arguments"));
+        return FAIL;
+      }
+    } else if (STRNICMP(attr, "range", attrlen) == 0) {
+      *argt |= EX_RANGE;
+      if (vallen == 1 && *val == '%') {
+        *argt |= EX_DFLALL;
+      } else if (val != NULL) {
+        p = val;
+        if (*def >= 0) {
+two_count:
+          emsg(_("E177: Count cannot be specified twice"));
+          return FAIL;
+        }
+
+        *def = getdigits_long(&p, true, 0);
+        *argt |= EX_ZEROR;
+
+        if (p != val + vallen || vallen == 0) {
+invalid_count:
+          emsg(_("E178: Invalid default value for count"));
+          return FAIL;
+        }
+      }
+      // default for -range is using buffer lines
+      if (*addr_type_arg == ADDR_NONE) {
+        *addr_type_arg = ADDR_LINES;
+      }
+    } else if (STRNICMP(attr, "count", attrlen) == 0) {
+      *argt |= (EX_COUNT | EX_ZEROR | EX_RANGE);
+      // default for -count is using any number
+      if (*addr_type_arg == ADDR_NONE) {
+        *addr_type_arg = ADDR_OTHER;
+      }
+
+      if (val != NULL) {
+        p = val;
+        if (*def >= 0) {
+          goto two_count;
+        }
+
+        *def = getdigits_long(&p, true, 0);
+
+        if (p != val + vallen) {
+          goto invalid_count;
+        }
+      }
+
+      if (*def < 0) {
+        *def = 0;
+      }
+    } else if (STRNICMP(attr, "complete", attrlen) == 0) {
+      if (val == NULL) {
+        emsg(_("E179: argument required for -complete"));
+        return FAIL;
+      }
+
+      if (parse_compl_arg(val, (int)vallen, complp, argt, (char **)compl_arg)
+          == FAIL) {
+        return FAIL;
+      }
+    } else if (STRNICMP(attr, "addr", attrlen) == 0) {
+      *argt |= EX_RANGE;
+      if (val == NULL) {
+        emsg(_("E179: argument required for -addr"));
+        return FAIL;
+      }
+      if (parse_addr_type_arg(val, (int)vallen, addr_type_arg) == FAIL) {
+        return FAIL;
+      }
+      if (*addr_type_arg != ADDR_LINES) {
+        *argt |= EX_ZEROR;
+      }
+    } else {
+      char ch = attr[len];
+      attr[len] = '\0';
+      semsg(_("E181: Invalid attribute: %s"), attr);
+      attr[len] = ch;
+      return FAIL;
+    }
+  }
+
+  return OK;
+}
+
+/// Check for a valid user command name
+///
+/// If the given {name} is valid, then a pointer to the end of the valid name is returned.
+/// Otherwise, returns NULL.
+char *uc_validate_name(char *name)
+{
+  if (ASCII_ISALPHA(*name)) {
+    while (ASCII_ISALNUM(*name)) {
+      name++;
+    }
+  }
+  if (!ends_excmd(*name) && !ascii_iswhite(*name)) {
+    return NULL;
+  }
+
+  return name;
+}
+
+/// Create a new user command {name}, if one doesn't already exist.
+///
+/// This function takes ownership of compl_arg, compl_luaref, and luaref.
+///
+/// @return  OK if the command is created, FAIL otherwise.
+int uc_add_command(char *name, size_t name_len, const char *rep, uint32_t argt, long def, int flags,
+                   int compl, char *compl_arg, LuaRef compl_luaref, LuaRef preview_luaref,
+                   cmd_addr_T addr_type, LuaRef luaref, bool force)
+  FUNC_ATTR_NONNULL_ARG(1, 3)
+{
+  ucmd_T *cmd = NULL;
+  int i;
+  int cmp = 1;
+  char *rep_buf = NULL;
+  garray_T *gap;
+
+  replace_termcodes(rep, STRLEN(rep), &rep_buf, 0, NULL, CPO_TO_CPO_FLAGS);
+  if (rep_buf == NULL) {
+    // Can't replace termcodes - try using the string as is
+    rep_buf = xstrdup(rep);
+  }
+
+  // get address of growarray: global or in curbuf
+  if (flags & UC_BUFFER) {
+    gap = &curbuf->b_ucmds;
+    if (gap->ga_itemsize == 0) {
+      ga_init(gap, (int)sizeof(ucmd_T), 4);
+    }
+  } else {
+    gap = &ucmds;
+  }
+
+  // Search for the command in the already defined commands.
+  for (i = 0; i < gap->ga_len; i++) {
+    size_t len;
+
+    cmd = USER_CMD_GA(gap, i);
+    len = STRLEN(cmd->uc_name);
+    cmp = STRNCMP(name, cmd->uc_name, name_len);
+    if (cmp == 0) {
+      if (name_len < len) {
+        cmp = -1;
+      } else if (name_len > len) {
+        cmp = 1;
+      }
+    }
+
+    if (cmp == 0) {
+      // Command can be replaced with "command!" and when sourcing the
+      // same script again, but only once.
+      if (!force
+          && (cmd->uc_script_ctx.sc_sid != current_sctx.sc_sid
+              || cmd->uc_script_ctx.sc_seq == current_sctx.sc_seq)) {
+        semsg(_("E174: Command already exists: add ! to replace it: %s"),
+              name);
+        goto fail;
+      }
+
+      XFREE_CLEAR(cmd->uc_rep);
+      XFREE_CLEAR(cmd->uc_compl_arg);
+      NLUA_CLEAR_REF(cmd->uc_luaref);
+      NLUA_CLEAR_REF(cmd->uc_compl_luaref);
+      NLUA_CLEAR_REF(cmd->uc_preview_luaref);
+      break;
+    }
+
+    // Stop as soon as we pass the name to add
+    if (cmp < 0) {
+      break;
+    }
+  }
+
+  // Extend the array unless we're replacing an existing command
+  if (cmp != 0) {
+    ga_grow(gap, 1);
+
+    char *const p = xstrnsave(name, name_len);
+
+    cmd = USER_CMD_GA(gap, i);
+    memmove(cmd + 1, cmd, (size_t)(gap->ga_len - i) * sizeof(ucmd_T));
+
+    gap->ga_len++;
+
+    cmd->uc_name = (char_u *)p;
+  }
+
+  cmd->uc_rep = (char_u *)rep_buf;
+  cmd->uc_argt = argt;
+  cmd->uc_def = def;
+  cmd->uc_compl = compl;
+  cmd->uc_script_ctx = current_sctx;
+  cmd->uc_script_ctx.sc_lnum += sourcing_lnum;
+  nlua_set_sctx(&cmd->uc_script_ctx);
+  cmd->uc_compl_arg = (char_u *)compl_arg;
+  cmd->uc_compl_luaref = compl_luaref;
+  cmd->uc_preview_luaref = preview_luaref;
+  cmd->uc_addr_type = addr_type;
+  cmd->uc_luaref = luaref;
+
+  return OK;
+
+fail:
+  xfree(rep_buf);
+  xfree(compl_arg);
+  NLUA_CLEAR_REF(luaref);
+  NLUA_CLEAR_REF(compl_luaref);
+  NLUA_CLEAR_REF(preview_luaref);
+  return FAIL;
+}
+
+/// ":command ..."
+void ex_command(exarg_T *eap)
+{
+  char *name;
+  char *end;
+  char *p;
+  uint32_t argt = 0;
+  long def = -1;
+  int flags = 0;
+  int compl = EXPAND_NOTHING;
+  char *compl_arg = NULL;
+  cmd_addr_T addr_type_arg = ADDR_NONE;
+  int has_attr = (eap->arg[0] == '-');
+  size_t name_len;
+
+  p = eap->arg;
+
+  // Check for attributes
+  while (*p == '-') {
+    p++;
+    end = (char *)skiptowhite((char_u *)p);
+    if (uc_scan_attr(p, (size_t)(end - p), &argt, &def, &flags, &compl, (char_u **)&compl_arg,
+                     &addr_type_arg) == FAIL) {
+      return;
+    }
+    p = skipwhite(end);
+  }
+
+  // Get the name (if any) and skip to the following argument.
+  name = p;
+  end = uc_validate_name(name);
+  if (!end) {
+    emsg(_("E182: Invalid command name"));
+    return;
+  }
+  name_len = (size_t)(end - name);
+
+  // If there is nothing after the name, and no attributes were specified,
+  // we are listing commands
+  p = skipwhite(end);
+  if (!has_attr && ends_excmd(*p)) {
+    uc_list(name, name_len);
+  } else if (!ASCII_ISUPPER(*name)) {
+    emsg(_("E183: User defined commands must start with an uppercase letter"));
+  } else if (name_len <= 4 && STRNCMP(name, "Next", name_len) == 0) {
+    emsg(_("E841: Reserved name, cannot be used for user defined command"));
+  } else if (compl > 0 && (argt & EX_EXTRA) == 0) {
+    emsg(_(e_complete_used_without_nargs));
+  } else {
+    uc_add_command(name, name_len, p, argt, def, flags, compl, compl_arg, LUA_NOREF, LUA_NOREF,
+                   addr_type_arg, LUA_NOREF, eap->forceit);
+  }
+}
+
+/// ":comclear"
+/// Clear all user commands, global and for current buffer.
+void ex_comclear(exarg_T *eap)
+{
+  uc_clear(&ucmds);
+  uc_clear(&curbuf->b_ucmds);
+}
+
+void free_ucmd(ucmd_T *cmd)
+{
+  xfree(cmd->uc_name);
+  xfree(cmd->uc_rep);
+  xfree(cmd->uc_compl_arg);
+  NLUA_CLEAR_REF(cmd->uc_compl_luaref);
+  NLUA_CLEAR_REF(cmd->uc_luaref);
+  NLUA_CLEAR_REF(cmd->uc_preview_luaref);
+}
+
+/// Clear all user commands for "gap".
+void uc_clear(garray_T *gap)
+{
+  GA_DEEP_CLEAR(gap, ucmd_T, free_ucmd);
+}
+
+void ex_delcommand(exarg_T *eap)
+{
+  int i = 0;
+  ucmd_T *cmd = NULL;
+  int res = -1;
+  garray_T *gap;
+  const char *arg = eap->arg;
+  bool buffer_only = false;
+
+  if (STRNCMP(arg, "-buffer", 7) == 0 && ascii_iswhite(arg[7])) {
+    buffer_only = true;
+    arg = skipwhite(arg + 7);
+  }
+
+  gap = &curbuf->b_ucmds;
+  for (;;) {
+    for (i = 0; i < gap->ga_len; i++) {
+      cmd = USER_CMD_GA(gap, i);
+      res = STRCMP(arg, cmd->uc_name);
+      if (res <= 0) {
+        break;
+      }
+    }
+    if (gap == &ucmds || res == 0 || buffer_only) {
+      break;
+    }
+    gap = &ucmds;
+  }
+
+  if (res != 0) {
+    semsg(_(buffer_only
+            ? e_no_such_user_defined_command_in_current_buffer_str
+            : e_no_such_user_defined_command_str),
+          arg);
+    return;
+  }
+
+  free_ucmd(cmd);
+
+  gap->ga_len--;
+
+  if (i < gap->ga_len) {
+    memmove(cmd, cmd + 1, (size_t)(gap->ga_len - i) * sizeof(ucmd_T));
+  }
+}
+
+/// Split a string by unescaped whitespace (space & tab), used for f-args on Lua commands callback.
+/// Similar to uc_split_args(), but does not allocate, add quotes, add commas and is an iterator.
+///
+/// @param[in]  arg String to split
+/// @param[in]  arglen Length of {arg}
+/// @param[inout] end Index of last character of previous iteration
+/// @param[out] buf Buffer to copy string into
+/// @param[out] len Length of string in {buf}
+///
+/// @return true if iteration is complete, else false
+bool uc_split_args_iter(const char *arg, size_t arglen, size_t *end, char *buf, size_t *len)
+{
+  if (!arglen) {
+    return true;
+  }
+
+  size_t pos = *end;
+  while (pos < arglen && ascii_iswhite(arg[pos])) {
+    pos++;
+  }
+
+  size_t l = 0;
+  for (; pos < arglen - 1; pos++) {
+    if (arg[pos] == '\\' && (arg[pos + 1] == '\\' || ascii_iswhite(arg[pos + 1]))) {
+      buf[l++] = arg[++pos];
+    } else {
+      buf[l++] = arg[pos];
+      if (ascii_iswhite(arg[pos + 1])) {
+        *end = pos + 1;
+        *len = l;
+        return false;
+      }
+    }
+  }
+
+  if (pos < arglen && !ascii_iswhite(arg[pos])) {
+    buf[l++] = arg[pos];
+  }
+
+  *len = l;
+  return true;
+}
+
+/// split and quote args for <f-args>
+static char *uc_split_args(char *arg, char **args, size_t *arglens, size_t argc, size_t *lenp)
+{
+  char *buf;
+  char *p;
+  char *q;
+  int len;
+
+  // Precalculate length
+  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;
+        }
+        len += 3;       // ","
+      } else {
+        const int charlen = utfc_ptr2len(p);
+
+        len += charlen;
+        p += charlen;
+      }
+    }
+  } 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;
+        }
+      }
+
+      if (i != argc - 1) {
+        len += 3;  // ","
+      }
+    }
+  }
+
+  buf = xmalloc((size_t)len + 1);
+
+  q = buf;
+  *q++ = '"';
+
+  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 = 0;
+
+  *lenp = (size_t)len;
+  return buf;
+}
+
+static size_t add_cmd_modifier(char *buf, char *mod_str, bool *multi_mods)
+{
+  size_t result = STRLEN(mod_str);
+  if (*multi_mods) {
+    result++;
+  }
+
+  if (buf != NULL) {
+    if (*multi_mods) {
+      STRCAT(buf, " ");
+    }
+    STRCAT(buf, mod_str);
+  }
+
+  *multi_mods = true;
+  return result;
+}
+
+/// Add modifiers from "cmod->cmod_split" to "buf".  Set "multi_mods" when one
+/// was added.
+///
+/// @return the number of bytes added
+size_t add_win_cmd_modifers(char *buf, const cmdmod_T *cmod, bool *multi_mods)
+{
+  size_t result = 0;
+
+  // :aboveleft and :leftabove
+  if (cmod->cmod_split & WSP_ABOVE) {
+    result += add_cmd_modifier(buf, "aboveleft", multi_mods);
+  }
+  // :belowright and :rightbelow
+  if (cmod->cmod_split & WSP_BELOW) {
+    result += add_cmd_modifier(buf, "belowright", multi_mods);
+  }
+  // :botright
+  if (cmod->cmod_split & WSP_BOT) {
+    result += add_cmd_modifier(buf, "botright", multi_mods);
+  }
+
+  // :tab
+  if (cmod->cmod_tab > 0) {
+    result += add_cmd_modifier(buf, "tab", multi_mods);
+  }
+  // :topleft
+  if (cmod->cmod_split & WSP_TOP) {
+    result += add_cmd_modifier(buf, "topleft", multi_mods);
+  }
+  // :vertical
+  if (cmod->cmod_split & WSP_VERT) {
+    result += add_cmd_modifier(buf, "vertical", multi_mods);
+  }
+  return result;
+}
+
+/// Generate text for the "cmod" command modifiers.
+/// If "buf" is NULL just return the length.
+size_t uc_mods(char *buf, const cmdmod_T *cmod, bool quote)
+{
+  size_t result = 0;
+  bool multi_mods = false;
+
+  typedef struct {
+    int flag;
+    char *name;
+  } mod_entry_T;
+  static mod_entry_T mod_entries[] = {
+    { CMOD_BROWSE, "browse" },
+    { CMOD_CONFIRM, "confirm" },
+    { CMOD_HIDE, "hide" },
+    { CMOD_KEEPALT, "keepalt" },
+    { CMOD_KEEPJUMPS, "keepjumps" },
+    { CMOD_KEEPMARKS, "keepmarks" },
+    { CMOD_KEEPPATTERNS, "keeppatterns" },
+    { CMOD_LOCKMARKS, "lockmarks" },
+    { CMOD_NOSWAPFILE, "noswapfile" },
+    { CMOD_UNSILENT, "unsilent" },
+    { CMOD_NOAUTOCMD, "noautocmd" },
+    { CMOD_SANDBOX, "sandbox" },
+  };
+
+  result = quote ? 2 : 0;
+  if (buf != NULL) {
+    if (quote) {
+      *buf++ = '"';
+    }
+    *buf = '\0';
+  }
+
+  // the modifiers that are simple flags
+  for (size_t i = 0; i < ARRAY_SIZE(mod_entries); i++) {
+    if (cmod->cmod_flags & mod_entries[i].flag) {
+      result += add_cmd_modifier(buf, mod_entries[i].name, &multi_mods);
+    }
+  }
+
+  // :silent
+  if (cmod->cmod_flags & CMOD_SILENT) {
+    result += add_cmd_modifier(buf,
+                               (cmod->cmod_flags & CMOD_ERRSILENT) ? "silent!" : "silent",
+                               &multi_mods);
+  }
+  // :verbose
+  if (cmod->cmod_verbose > 0) {
+    int verbose_value = cmod->cmod_verbose - 1;
+    if (verbose_value == 1) {
+      result += add_cmd_modifier(buf, "verbose", &multi_mods);
+    } else {
+      char verbose_buf[NUMBUFLEN];
+      snprintf(verbose_buf, NUMBUFLEN, "%dverbose", verbose_value);
+      result += add_cmd_modifier(buf, verbose_buf, &multi_mods);
+    }
+  }
+  // flags from cmod->cmod_split
+  result += add_win_cmd_modifers(buf, cmod, &multi_mods);
+
+  if (quote && buf != NULL) {
+    buf += result - 2;
+    *buf = '"';
+  }
+  return result;
+}
+
+/// Check for a <> code in a user command.
+///
+/// @param code       points to the '<'.  "len" the length of the <> (inclusive).
+/// @param buf        is where the result is to be added.
+/// @param cmd        the user command we're expanding
+/// @param eap        ex arguments
+/// @param split_buf  points to a buffer used for splitting, caller should free it.
+/// @param split_len  is the length of what "split_buf" contains.
+///
+/// @return           the length of the replacement, which has been added to "buf".
+///                   Return -1 if there was no match, and only the "<" has been copied.
+static size_t uc_check_code(char *code, size_t len, char *buf, ucmd_T *cmd, exarg_T *eap,
+                            char **split_buf, size_t *split_len)
+{
+  size_t result = 0;
+  char *p = code + 1;
+  size_t l = len - 2;
+  int quote = 0;
+  enum {
+    ct_ARGS,
+    ct_BANG,
+    ct_COUNT,
+    ct_LINE1,
+    ct_LINE2,
+    ct_RANGE,
+    ct_MODS,
+    ct_REGISTER,
+    ct_LT,
+    ct_NONE,
+  } type = ct_NONE;
+
+  if ((vim_strchr("qQfF", *p) != NULL) && p[1] == '-') {
+    quote = (*p == 'q' || *p == 'Q') ? 1 : 2;
+    p += 2;
+    l -= 2;
+  }
+
+  l++;
+  if (l <= 1) {
+    type = ct_NONE;
+  } else if (STRNICMP(p, "args>", l) == 0) {
+    type = ct_ARGS;
+  } else if (STRNICMP(p, "bang>", l) == 0) {
+    type = ct_BANG;
+  } else if (STRNICMP(p, "count>", l) == 0) {
+    type = ct_COUNT;
+  } else if (STRNICMP(p, "line1>", l) == 0) {
+    type = ct_LINE1;
+  } else if (STRNICMP(p, "line2>", l) == 0) {
+    type = ct_LINE2;
+  } else if (STRNICMP(p, "range>", l) == 0) {
+    type = ct_RANGE;
+  } else if (STRNICMP(p, "lt>", l) == 0) {
+    type = ct_LT;
+  } else if (STRNICMP(p, "reg>", l) == 0 || STRNICMP(p, "register>", l) == 0) {
+    type = ct_REGISTER;
+  } else if (STRNICMP(p, "mods>", l) == 0) {
+    type = ct_MODS;
+  }
+
+  switch (type) {
+  case ct_ARGS:
+    // Simple case first
+    if (*eap->arg == NUL) {
+      if (quote == 1) {
+        result = 2;
+        if (buf != NULL) {
+          STRCPY(buf, "''");
+        }
+      } else {
+        result = 0;
+      }
+      break;
+    }
+
+    // When specified there is a single argument don't split it.
+    // Works for ":Cmd %" when % is "a b c".
+    if ((eap->argt & EX_NOSPC) && quote == 2) {
+      quote = 1;
+    }
+
+    switch (quote) {
+    case 0:     // No quoting, no splitting
+      result = STRLEN(eap->arg);
+      if (buf != NULL) {
+        STRCPY(buf, eap->arg);
+      }
+      break;
+    case 1:     // Quote, but don't split
+      result = STRLEN(eap->arg) + 2;
+      for (p = eap->arg; *p; p++) {
+        if (*p == '\\' || *p == '"') {
+          result++;
+        }
+      }
+
+      if (buf != NULL) {
+        *buf++ = '"';
+        for (p = eap->arg; *p; p++) {
+          if (*p == '\\' || *p == '"') {
+            *buf++ = '\\';
+          }
+          *buf++ = *p;
+        }
+        *buf = '"';
+      }
+
+      break;
+    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, eap->args, eap->arglens, eap->argc, split_len);
+      }
+
+      result = *split_len;
+      if (buf != NULL && result != 0) {
+        STRCPY(buf, *split_buf);
+      }
+
+      break;
+    }
+    break;
+
+  case ct_BANG:
+    result = eap->forceit ? 1 : 0;
+    if (quote) {
+      result += 2;
+    }
+    if (buf != NULL) {
+      if (quote) {
+        *buf++ = '"';
+      }
+      if (eap->forceit) {
+        *buf++ = '!';
+      }
+      if (quote) {
+        *buf = '"';
+      }
+    }
+    break;
+
+  case ct_LINE1:
+  case ct_LINE2:
+  case ct_RANGE:
+  case ct_COUNT: {
+    char num_buf[20];
+    long num = (type == ct_LINE1) ? eap->line1 :
+               (type == ct_LINE2) ? eap->line2 :
+               (type == ct_RANGE) ? eap->addr_count :
+               (eap->addr_count > 0) ? eap->line2 : cmd->uc_def;
+    size_t num_len;
+
+    snprintf(num_buf, sizeof(num_buf), "%" PRId64, (int64_t)num);
+    num_len = STRLEN(num_buf);
+    result = num_len;
+
+    if (quote) {
+      result += 2;
+    }
+
+    if (buf != NULL) {
+      if (quote) {
+        *buf++ = '"';
+      }
+      STRCPY(buf, num_buf);
+      buf += num_len;
+      if (quote) {
+        *buf = '"';
+      }
+    }
+
+    break;
+  }
+
+  case ct_MODS:
+    result = uc_mods(buf, &cmdmod, quote);
+    break;
+
+  case ct_REGISTER:
+    result = eap->regname ? 1 : 0;
+    if (quote) {
+      result += 2;
+    }
+    if (buf != NULL) {
+      if (quote) {
+        *buf++ = '\'';
+      }
+      if (eap->regname) {
+        *buf++ = (char)eap->regname;
+      }
+      if (quote) {
+        *buf = '\'';
+      }
+    }
+    break;
+
+  case ct_LT:
+    result = 1;
+    if (buf != NULL) {
+      *buf = '<';
+    }
+    break;
+
+  default:
+    // Not recognized: just copy the '<' and return -1.
+    result = (size_t)-1;
+    if (buf != NULL) {
+      *buf = '<';
+    }
+    break;
+  }
+
+  return result;
+}
+
+int do_ucmd(exarg_T *eap, bool preview)
+{
+  char *buf;
+  char *p;
+  char *q;
+
+  char *start;
+  char *end = NULL;
+  char *ksp;
+  size_t len, totlen;
+
+  size_t split_len = 0;
+  char *split_buf = NULL;
+  ucmd_T *cmd;
+
+  if (eap->cmdidx == CMD_USER) {
+    cmd = USER_CMD(eap->useridx);
+  } else {
+    cmd = USER_CMD_GA(&curbuf->b_ucmds, eap->useridx);
+  }
+
+  if (preview) {
+    assert(cmd->uc_preview_luaref > 0);
+    return nlua_do_ucmd(cmd, eap, true);
+  }
+
+  if (cmd->uc_luaref > 0) {
+    nlua_do_ucmd(cmd, eap, false);
+    return 0;
+  }
+
+  // Replace <> in the command by the arguments.
+  // First round: "buf" is NULL, compute length, allocate "buf".
+  // Second round: copy result into "buf".
+  buf = NULL;
+  for (;;) {
+    p = (char *)cmd->uc_rep;        // source
+    q = buf;                // destination
+    totlen = 0;
+
+    for (;;) {
+      start = vim_strchr(p, '<');
+      if (start != NULL) {
+        end = vim_strchr(start + 1, '>');
+      }
+      if (buf != NULL) {
+        for (ksp = p; *ksp != NUL && (char_u)(*ksp) != K_SPECIAL; ksp++) {}
+        if ((char_u)(*ksp) == K_SPECIAL
+            && (start == NULL || ksp < start || end == NULL)
+            && ((char_u)ksp[1] == KS_SPECIAL && ksp[2] == KE_FILLER)) {
+          // K_SPECIAL has been put in the buffer as K_SPECIAL
+          // KS_SPECIAL KE_FILLER, like for mappings, but
+          // do_cmdline() doesn't handle that, so convert it back.
+          len = (size_t)(ksp - p);
+          if (len > 0) {
+            memmove(q, p, len);
+            q += len;
+          }
+          *q++ = (char)K_SPECIAL;
+          p = ksp + 3;
+          continue;
+        }
+      }
+
+      // break if no <item> is found
+      if (start == NULL || end == NULL) {
+        break;
+      }
+
+      // Include the '>'
+      end++;
+
+      // Take everything up to the '<'
+      len = (size_t)(start - p);
+      if (buf == NULL) {
+        totlen += len;
+      } else {
+        memmove(q, p, len);
+        q += len;
+      }
+
+      len = uc_check_code(start, (size_t)(end - start), q, cmd, eap, &split_buf, &split_len);
+      if (len == (size_t)-1) {
+        // no match, continue after '<'
+        p = start + 1;
+        len = 1;
+      } else {
+        p = end;
+      }
+      if (buf == NULL) {
+        totlen += len;
+      } else {
+        q += len;
+      }
+    }
+    if (buf != NULL) {              // second time here, finished
+      STRCPY(q, p);
+      break;
+    }
+
+    totlen += STRLEN(p);            // Add on the trailing characters
+    buf = xmalloc(totlen + 1);
+  }
+
+  sctx_T save_current_sctx;
+  bool restore_current_sctx = false;
+  if ((cmd->uc_argt & EX_KEEPSCRIPT) == 0) {
+    restore_current_sctx = true;
+    save_current_sctx = current_sctx;
+    current_sctx.sc_sid = cmd->uc_script_ctx.sc_sid;
+  }
+  (void)do_cmdline(buf, eap->getline, eap->cookie,
+                   DOCMD_VERBOSE|DOCMD_NOWAIT|DOCMD_KEYTYPED);
+
+  // Careful: Do not use "cmd" here, it may have become invalid if a user
+  // command was added.
+  if (restore_current_sctx) {
+    current_sctx = save_current_sctx;
+  }
+  xfree(buf);
+  xfree(split_buf);
+
+  return 0;
+}
+
+/// Gets a map of maps describing user-commands defined for buffer `buf` or
+/// defined globally if `buf` is NULL.
+///
+/// @param buf  Buffer to inspect, or NULL to get global commands.
+///
+/// @return Map of maps describing commands
+Dictionary commands_array(buf_T *buf)
+{
+  Dictionary rv = ARRAY_DICT_INIT;
+  char str[20];
+  garray_T *gap = (buf == NULL) ? &ucmds : &buf->b_ucmds;
+
+  for (int i = 0; i < gap->ga_len; i++) {
+    char arg[2] = { 0, 0 };
+    Dictionary d = ARRAY_DICT_INIT;
+    ucmd_T *cmd = USER_CMD_GA(gap, i);
+
+    PUT(d, "name", STRING_OBJ(cstr_to_string((char *)cmd->uc_name)));
+    PUT(d, "definition", STRING_OBJ(cstr_to_string((char *)cmd->uc_rep)));
+    PUT(d, "script_id", INTEGER_OBJ(cmd->uc_script_ctx.sc_sid));
+    PUT(d, "bang", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_BANG)));
+    PUT(d, "bar", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_TRLBAR)));
+    PUT(d, "register", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_REGSTR)));
+    PUT(d, "keepscript", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_KEEPSCRIPT)));
+    PUT(d, "preview", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_PREVIEW)));
+
+    switch (cmd->uc_argt & (EX_EXTRA | EX_NOSPC | EX_NEEDARG)) {
+    case 0:
+      arg[0] = '0'; break;
+    case (EX_EXTRA):
+      arg[0] = '*'; break;
+    case (EX_EXTRA | EX_NOSPC):
+      arg[0] = '?'; break;
+    case (EX_EXTRA | EX_NEEDARG):
+      arg[0] = '+'; break;
+    case (EX_EXTRA | EX_NOSPC | EX_NEEDARG):
+      arg[0] = '1'; break;
+    }
+    PUT(d, "nargs", STRING_OBJ(cstr_to_string(arg)));
+
+    char *cmd_compl = get_command_complete(cmd->uc_compl);
+    PUT(d, "complete", (cmd_compl == NULL
+                        ? NIL : STRING_OBJ(cstr_to_string(cmd_compl))));
+    PUT(d, "complete_arg", cmd->uc_compl_arg == NULL
+        ? NIL : STRING_OBJ(cstr_to_string((char *)cmd->uc_compl_arg)));
+
+    Object obj = NIL;
+    if (cmd->uc_argt & EX_COUNT) {
+      if (cmd->uc_def >= 0) {
+        snprintf(str, sizeof(str), "%" PRId64, (int64_t)cmd->uc_def);
+        obj = STRING_OBJ(cstr_to_string(str));    // -count=N
+      } else {
+        obj = STRING_OBJ(cstr_to_string("0"));    // -count
+      }
+    }
+    PUT(d, "count", obj);
+
+    obj = NIL;
+    if (cmd->uc_argt & EX_RANGE) {
+      if (cmd->uc_argt & EX_DFLALL) {
+        obj = STRING_OBJ(cstr_to_string("%"));    // -range=%
+      } else if (cmd->uc_def >= 0) {
+        snprintf(str, sizeof(str), "%" PRId64, (int64_t)cmd->uc_def);
+        obj = STRING_OBJ(cstr_to_string(str));    // -range=N
+      } else {
+        obj = STRING_OBJ(cstr_to_string("."));    // -range
+      }
+    }
+    PUT(d, "range", obj);
+
+    obj = NIL;
+    for (int j = 0; addr_type_complete[j].expand != ADDR_NONE; j++) {
+      if (addr_type_complete[j].expand != ADDR_LINES
+          && addr_type_complete[j].expand == cmd->uc_addr_type) {
+        obj = STRING_OBJ(cstr_to_string(addr_type_complete[j].name));
+        break;
+      }
+    }
+    PUT(d, "addr", obj);
+
+    PUT(rv, (char *)cmd->uc_name, DICTIONARY_OBJ(d));
+  }
+  return rv;
+}
diff --git a/src/nvim/usercmd.h b/src/nvim/usercmd.h
new file mode 100644
index 0000000000..637862b216
--- /dev/null
+++ b/src/nvim/usercmd.h
@@ -0,0 +1,30 @@
+#ifndef NVIM_USERCMD_H
+#define NVIM_USERCMD_H
+
+#include "nvim/ex_cmds_defs.h"
+
+typedef struct ucmd {
+  char_u *uc_name;              // The command name
+  uint32_t uc_argt;             // The argument type
+  char_u *uc_rep;               // The command's replacement string
+  long uc_def;                  // The default value for a range/count
+  int uc_compl;                 // completion type
+  cmd_addr_T uc_addr_type;      // The command's address type
+  sctx_T uc_script_ctx;         // SCTX where the command was defined
+  char_u *uc_compl_arg;         // completion argument if any
+  LuaRef uc_compl_luaref;       // Reference to Lua completion function
+  LuaRef uc_preview_luaref;     // Reference to Lua preview function
+  LuaRef uc_luaref;             // Reference to Lua function
+} ucmd_T;
+
+#define UC_BUFFER       1       // -buffer: local to current buffer
+
+extern garray_T ucmds;
+
+#define USER_CMD(i) (&((ucmd_T *)(ucmds.ga_data))[i])
+#define USER_CMD_GA(gap, i) (&((ucmd_T *)((gap)->ga_data))[i])
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "usercmd.h.generated.h"
+#endif
+#endif  // NVIM_USERCMD_H