neovim

usercmd.c (49467B)

---

// usercmd.c: User defined command support

#include <assert.h>
#include <inttypes.h>
#include <lauxlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>

#include "auto/config.h"
#include "nvim/api/private/helpers.h"
#include "nvim/ascii_defs.h"
#include "nvim/buffer_defs.h"
#include "nvim/charset.h"
#include "nvim/cmdexpand_defs.h"
#include "nvim/eval.h"
#include "nvim/ex_docmd.h"
#include "nvim/garray.h"
#include "nvim/gettext_defs.h"
#include "nvim/globals.h"
#include "nvim/highlight_defs.h"
#include "nvim/keycodes.h"
#include "nvim/lua/executor.h"
#include "nvim/macros_defs.h"
#include "nvim/mapping.h"
#include "nvim/mbyte.h"
#include "nvim/memory.h"
#include "nvim/memory_defs.h"
#include "nvim/menu.h"
#include "nvim/message.h"
#include "nvim/option_vars.h"
#include "nvim/os/input.h"
#include "nvim/runtime.h"
#include "nvim/strings.h"
#include "nvim/usercmd.h"
#include "nvim/vim_defs.h"
#include "nvim/window.h"

#include "usercmd.c.generated.h"

garray_T ucmds = { 0, 0, sizeof(ucmd_T), 4, NULL };

static const char e_argument_required_for_str[]
 = N_("E179: Argument required for %s");
static const char e_no_such_user_defined_command_str[]
 = N_("E184: No such user-defined command: %s");
static const char e_complete_used_without_allowing_arguments[]
 = N_("E1208: -complete used without allowing arguments");
static const 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_BUFFERS] = "buffer",
 [EXPAND_CHECKHEALTH] = "checkhealth",
 [EXPAND_COLORS] = "color",
 [EXPAND_COMMANDS] = "command",
 [EXPAND_COMPILER] = "compiler",
 [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_FILETYPECMD] = "filetypecmd",
 [EXPAND_FUNCTIONS] = "function",
 [EXPAND_HELP] = "help",
 [EXPAND_HIGHLIGHT] = "highlight",
 [EXPAND_HISTORY] = "history",
 [EXPAND_KEYMAP] = "keymap",
#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_RETAB] = "retab",
 [EXPAND_RUNTIME] = "runtime",
 [EXPAND_SHELLCMD] = "shellcmd",
 [EXPAND_SHELLCMDLINE] = "shellcmdline",
 [EXPAND_SIGN] = "sign",
 [EXPAND_TAGS] = "tag",
 [EXPAND_TAGS_LISTFILES] = "tag_listfiles",
 [EXPAND_USER] = "user",
 [EXPAND_USER_VARS] = "var",
 [EXPAND_BREAKPOINT] = "breakpoint",
 [EXPAND_SCRIPTNAMES] = "scriptnames",
 [EXPAND_DIRS_IN_CDPATH] = "dir_in_path",
};

/// 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 matchlen = 0;
 bool found = false;
 bool possible = false;
 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.
 garray_T *gap = &prevwin_curwin()->w_buffer->b_ucmds;
 while (true) {
   int j;
   for (j = 0; j < gap->ga_len; j++) {
     ucmd_T *uc = USER_CMD_GA(gap, j);
     char *cp = eap->cmd;
     char *np = uc->uc_name;
     int 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 = 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;
}

/// Set completion context for :command
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 = skiptowhite(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 = skipwhite(p);
 }

 // After the attributes comes the new command name.
 p = skiptowhite(arg);
 if (*p == NUL) {
   xp->xp_context = EXPAND_USER_COMMANDS;
   xp->xp_pattern = (char *)arg;
   return NULL;
 }

 // And finally comes a normal command.
 return skipwhite(p);
}

/// Set the completion context for the argument of a user defined command.
const char *set_context_in_user_cmdarg(const char *cmd FUNC_ATTR_UNUSED, const char *arg,
                                      uint32_t argt, int context, expand_T *xp, bool forceit)
{
 if (context == EXPAND_NOTHING) {
   return NULL;
 }

 if (argt & EX_XFILE) {
   // EX_XFILE: file names are handled before this call.
   return NULL;
 }

 if (context == EXPAND_MENUS) {
   return set_context_in_menu_cmd(xp, cmd, (char *)arg, forceit);
 }
 if (context == EXPAND_COMMANDS) {
   return arg;
 }
 if (context == EXPAND_MAPPINGS) {
   return set_context_in_map_cmd(xp, "map", (char *)arg, forceit, false, false,
                                 CMD_map);
 }
 // Find start of last argument.
 const char *p = arg;
 while (*p) {
   if (*p == ' ') {
     // argument starts after a space
     arg = p + 1;
   } else if (*p == '\\' && *(p + 1) != NUL) {
     p++;  // skip over escaped character
   }
   MB_PTR_ADV(p);
 }
 xp->xp_pattern = (char *)arg;
 xp->xp_context = context;

 return NULL;
}

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 USER_CMD_GA(&buf->b_ucmds, idx)->uc_name;
 }

 idx -= buf->b_ucmds.ga_len;
 if (idx < ucmds.ga_len) {
   char *name = 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 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 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 < 0 || arg >= (int)(ARRAY_SIZE(command_complete))) {
   return NULL;
 }
 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 || idx == EXPAND_USER_LUA) {
   return "";
 }
 return cmd_compl;
}

/// Get the name of completion type "expand" as an allocated string.
/// "compl_arg" is the function name for "custom" and "customlist" types.
/// Returns NULL if no completion is available.
char *cmdcomplete_type_to_str(int expand, const char *compl_arg)
{
 char *cmd_compl = get_command_complete(expand);
 if (cmd_compl == NULL || expand == EXPAND_USER_LUA) {
   return NULL;
 }

 if (expand == EXPAND_USER_LIST || expand == EXPAND_USER_DEFINED) {
   size_t buflen = strlen(cmd_compl) + strlen(compl_arg) + 2;
   char *buffer = xmalloc(buflen);
   snprintf(buffer, buflen, "%s,%s", cmd_compl, compl_arg);
   return buffer;
 }

 return xstrdup(cmd_compl);
}

int cmdcomplete_str_to_type(const char *complete_str)
{
 if (strncmp(complete_str, "custom,", 7) == 0) {
   return EXPAND_USER_DEFINED;
 }
 if (strncmp(complete_str, "customlist,", 11) == 0) {
   return EXPAND_USER_LIST;
 }

 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)
{
 bool found = false;

 msg_ext_set_kind("list_cmd");
 // In cmdwin, the alternative buffer should be used.
 const garray_T *gap = &prevwin_curwin()->w_buffer->b_ucmds;
 while (true) {
   int i;
   for (i = 0; i < gap->ga_len; i++) {
     ucmd_T *cmd = USER_CMD_GA(gap, i);
     uint32_t 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
     size_t 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--;
     }
     if (len != 0) {
       msg_puts(&"    "[4 - len]);
     }

     msg_outtrans(cmd->uc_name, HLF_D, false);
     len = strlen(cmd->uc_name) + 4;

     if (len < 21) {
       // Field padding spaces   12345678901234567
       static char spaces[18] = "                 ";
       msg_puts(&spaces[len - 4]);
       len = 21;
     }
     msg_putchar(' ');
     len++;

     // "over" is how much longer the name is than the column width for
     // the name, we'll try to align what comes after.
     const int64_t over = (int64_t)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 ((int64_t)len < 5 - over);

     // Address / Range
     if (a & (EX_RANGE | EX_COUNT)) {
       if (a & EX_COUNT) {
         // -count=N
         int rc = snprintf(IObuff + len, IOSIZE - len, "%" PRId64 "c", cmd->uc_def);
         assert(rc > 0);
         len += (size_t)rc;
       } else if (a & EX_DFLALL) {
         IObuff[len++] = '%';
       } else if (cmd->uc_def >= 0) {
         // -range=N
         int rc = snprintf(IObuff + len, IOSIZE - len, "%" PRId64 "", cmd->uc_def);
         assert(rc > 0);
         len += (size_t)rc;
       } else {
         IObuff[len++] = '.';
       }
     }

     do {
       IObuff[len++] = ' ';
     } while ((int64_t)len < 8 - over);

     // Address Type
     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) {
         int rc = snprintf(IObuff + len, IOSIZE - len, "%s", addr_type_complete[j].shortname);
         assert(rc > 0);
         len += (size_t)rc;
         break;
       }
     }

     do {
       IObuff[len++] = ' ';
     } while ((int64_t)len < 13 - over);

     // Completion
     char *cmd_compl = get_command_complete(cmd->uc_compl);
     if (cmd_compl != NULL) {
       int rc = snprintf(IObuff + len, IOSIZE - len, "%s", get_command_complete(cmd->uc_compl));
       assert(rc > 0);
       len += (size_t)rc;
     }

     do {
       IObuff[len++] = ' ';
     } while ((int64_t)len < 25 - over);

     IObuff[len] = NUL;
     msg_outtrans(IObuff, 0, false);

     if (cmd->uc_luaref != LUA_NOREF) {
       char *fn = nlua_funcref_str(cmd->uc_luaref, NULL);
       msg_puts_hl(fn, HLF_8, false);
       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"), 0);
 }
}

/// 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;

 for (i = 0; addr_type_complete[i].expand != ADDR_NONE; i++) {
   int a = (int)strlen(addr_type_complete[i].name) == vallen;
   int b = strncmp(value, addr_type_complete[i].name, (size_t)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 valend = vallen;

 // Look for any argument part - which is the part after any ','
 for (int i = 0; i < vallen; i++) {
   if (value[i] == ',') {
     arg = (char *)&value[i + 1];
     arglen = (size_t)(vallen - i - 1);
     valend = i;
     break;
   }
 }

 int i;
 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], (size_t)valend) == 0) {
     *complp = i;
     if (i == EXPAND_BUFFERS) {
       *argt |= EX_BUFNAME;
     } else if (i == EXPAND_DIRECTORIES || i == EXPAND_FILES
                || i == EXPAND_SHELLCMDLINE) {
       *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, int *def, int *flags, int *complp,
                       char **compl_arg, cmd_addr_T *addr_type_arg)
 FUNC_ATTR_NONNULL_ALL
{
 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 {
   char *val = NULL;
   size_t vallen = 0;
   size_t attrlen = len;

   // Look for the attribute name - which is the part before any '='
   for (int 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) {
       char *p = val;
       if (*def >= 0) {
two_count:
         emsg(_("E177: Count cannot be specified twice"));
         return FAIL;
       }

       *def = getdigits_int(&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) {
       char *p = val;
       if (*def >= 0) {
         goto two_count;
       }

       *def = getdigits_int(&p, true, 0);

       if (p != val + vallen) {
         goto invalid_count;
       }
     }

     *def = MAX(*def, 0);
   } else if (STRNICMP(attr, "complete", attrlen) == 0) {
     if (val == NULL) {
       semsg(_(e_argument_required_for_str), "-complete");
       return FAIL;
     }

     if (parse_compl_arg(val, (int)vallen, complp, argt, compl_arg)
         == FAIL) {
       return FAIL;
     }
   } else if (STRNICMP(attr, "addr", attrlen) == 0) {
     *argt |= EX_RANGE;
     if (val == NULL) {
       semsg(_(e_argument_required_for_str), "-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] = NUL;
     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, int64_t def,
                  int flags, int context, 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 cmp = 1;
 char *rep_buf = NULL;
 garray_T *gap;

 replace_termcodes(rep, strlen(rep), &rep_buf, 0, 0, NULL, p_cpo);
 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;
 }

 int i;

 // Search for the command in the already defined commands.
 for (i = 0; i < gap->ga_len; i++) {
   cmd = USER_CMD_GA(gap, i);
   size_t 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 = p;
 }

 cmd->uc_rep = rep_buf;
 cmd->uc_argt = argt;
 cmd->uc_def = def;
 cmd->uc_compl = context;
 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 = 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 *end;
 uint32_t argt = 0;
 int def = -1;
 int flags = 0;
 int context = EXPAND_NOTHING;
 char *compl_arg = NULL;
 cmd_addr_T addr_type_arg = ADDR_NONE;
 int has_attr = (eap->arg[0] == '-');

 char *p = eap->arg;

 // Check for attributes
 while (*p == '-') {
   p++;
   end = skiptowhite(p);
   if (uc_scan_attr(p, (size_t)(end - p), &argt, &def, &flags, &context, &compl_arg,
                    &addr_type_arg) == FAIL) {
     goto theend;
   }
   p = skipwhite(end);
 }

 // Get the name (if any) and skip to the following argument.
 char *name = p;
 end = uc_validate_name(name);
 if (!end) {
   emsg(_("E182: Invalid command name"));
   goto theend;
 }
 size_t 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 (context > 0 && (argt & EX_EXTRA) == 0) {
   emsg(_(e_complete_used_without_allowing_arguments));
 } else {
   uc_add_command(name, name_len, p, argt, def, flags, context, compl_arg, LUA_NOREF, LUA_NOREF,
                  addr_type_arg, LUA_NOREF, eap->forceit);

   return;  // success
 }

theend:
 xfree(compl_arg);
}

/// ":comclear"
/// Clear all user commands, global and for current buffer.
void ex_comclear(exarg_T *eap)
{
 uc_clear(&ucmds);
 if (curbuf != NULL) {
   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;
 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);
 }

 garray_T *gap = &curbuf->b_ucmds;
 while (true) {
   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;
}

size_t uc_nargs_upper_bound(const char *arg, size_t arglen)
{
 bool was_white = true;  // space before first arg
 size_t nargs = 0;
 for (size_t i = 0; i < arglen; i++) {
   bool is_white = ascii_iswhite(arg[i]);
   if (was_white && !is_white) {
     nargs++;
   }
   was_white = is_white;
 }
 return nargs;
}

/// split and quote args for <f-args>
static char *uc_split_args(const char *arg, char **args, const size_t *arglens, size_t argc,
                          size_t *lenp)
{
 // Precalculate length
 int len = 2;   // Initial and final quotes
 if (args == NULL) {
   const char *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 += 4;  // ", "
     } else {
       const int charlen = utfc_ptr2len(p);

       len += charlen;
       p += charlen;
     }
   }
 } else {
   for (size_t i = 0; i < argc; i++) {
     const char *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 += 4;  // ", "
     }
   }
 }

 char *buf = xmalloc((size_t)len + 1);

 char *q = buf;
 *q++ = '"';

 if (args == NULL) {
   const char *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++ = ' ';
       *q++ = '"';
     } else {
       mb_copy_char(&p, &q);
     }
   }
 } else {
   for (size_t i = 0; i < argc; i++) {
     const char *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(&p, &q);
       }
     }
     if (i != argc - 1) {
       *q++ = '"';
       *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_modifiers(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) {
   int tabnr = cmod->cmod_tab - 1;
   if (tabnr == tabpage_index(curtab)) {
     // For compatibility, don't add a tabpage number if it is the same
     // as the default number for :tab.
     result += add_cmd_modifier(buf, "tab", multi_mods);
   } else {
     char tab_buf[NUMBUFLEN + 3];
     snprintf(tab_buf, sizeof(tab_buf), "%dtab", tabnr);
     result += add_cmd_modifier(buf, tab_buf, 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);
 }
 // :horizontal
 if (cmod->cmod_split & WSP_HOR) {
   result += add_cmd_modifier(buf, "horizontal", 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 = NUL;
 }

 // 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, sizeof(verbose_buf), "%dverbose", verbose_value);
     result += add_cmd_modifier(buf, verbose_buf, &multi_mods);
   }
 }
 // flags from cmod->cmod_split
 result += add_win_cmd_modifiers(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", (uint8_t)(*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];
   int64_t 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, 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 *end = NULL;

 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(&prevwin_curwin()->w_buffer->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".
 char *buf = NULL;
 while (true) {
   char *p = cmd->uc_rep;        // source
   char *q = buf;                // destination
   size_t totlen = 0;

   while (true) {
     char *start = vim_strchr(p, '<');
     if (start != NULL) {
       end = vim_strchr(start + 1, '>');
     }
     if (buf != NULL) {
       char *ksp;
       for (ksp = p; *ksp != NUL && (uint8_t)(*ksp) != K_SPECIAL; ksp++) {}
       if ((uint8_t)(*ksp) == K_SPECIAL
           && (start == NULL || ksp < start || end == NULL)
           && ((uint8_t)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.
         size_t 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 '<'
     size_t 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;
 }
 do_cmdline(buf, eap->ea_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
Dict commands_array(buf_T *buf, Arena *arena)
{
 garray_T *gap = (buf == NULL) ? &ucmds : &buf->b_ucmds;

 Dict rv = arena_dict(arena, (size_t)gap->ga_len);
 for (int i = 0; i < gap->ga_len; i++) {
   char arg[2] = { 0, 0 };
   Dict d = arena_dict(arena, 16);
   ucmd_T *cmd = USER_CMD_GA(gap, i);

   PUT_C(d, "name", CSTR_AS_OBJ(cmd->uc_name));
   PUT_C(d, "definition", CSTR_AS_OBJ(cmd->uc_rep));
   PUT_C(d, "script_id", INTEGER_OBJ(cmd->uc_script_ctx.sc_sid));
   PUT_C(d, "bang", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_BANG)));
   PUT_C(d, "bar", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_TRLBAR)));
   PUT_C(d, "register", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_REGSTR)));
   PUT_C(d, "keepscript", BOOLEAN_OBJ(!!(cmd->uc_argt & EX_KEEPSCRIPT)));

   if (cmd->uc_preview_luaref != LUA_NOREF) {
     PUT_C(d, "preview", LUAREF_OBJ(api_new_luaref(cmd->uc_preview_luaref)));
   }

   if (cmd->uc_luaref != LUA_NOREF) {
     PUT_C(d, "callback", LUAREF_OBJ(api_new_luaref(cmd->uc_luaref)));
   }

   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_C(d, "nargs", CSTR_TO_ARENA_OBJ(arena, arg));

   if (cmd->uc_compl_luaref != LUA_NOREF) {
     PUT_C(d, "complete", LUAREF_OBJ(api_new_luaref(cmd->uc_compl_luaref)));
   } else {
     char *cmd_compl = get_command_complete(cmd->uc_compl);
     PUT_C(d, "complete", (cmd_compl == NULL ? NIL : CSTR_AS_OBJ(cmd_compl)));
   }
   PUT_C(d, "complete_arg", cmd->uc_compl_arg == NULL
         ? NIL : CSTR_AS_OBJ(cmd->uc_compl_arg));

   Object obj = NIL;
   if (cmd->uc_argt & EX_COUNT) {
     if (cmd->uc_def >= 0) {
       obj = STRING_OBJ(arena_printf(arena, "%" PRId64, cmd->uc_def));    // -count=N
     } else {
       obj = CSTR_AS_OBJ("0");    // -count
     }
   }
   PUT_C(d, "count", obj);

   obj = NIL;
   if (cmd->uc_argt & EX_RANGE) {
     if (cmd->uc_argt & EX_DFLALL) {
       obj = STATIC_CSTR_AS_OBJ("%");    // -range=%
     } else if (cmd->uc_def >= 0) {
       obj = STRING_OBJ(arena_printf(arena, "%" PRId64, cmd->uc_def));    // -range=N
     } else {
       obj = STATIC_CSTR_AS_OBJ(".");    // -range
     }
   }
   PUT_C(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 = CSTR_AS_OBJ(addr_type_complete[j].name);
       break;
     }
   }
   PUT_C(d, "addr", obj);

   PUT_C(rv, cmd->uc_name, DICT_OBJ(d));
 }
 return rv;
}