text: /* vi:set ts=8 sts=4 sw=4 noet:
   *
   * VIM - Vi IMproved	by Bram Moolenaar
   *
   * Do ":help uganda"  in Vim to read copying and usage conditions.
   * Do ":help credits" in Vim to see a list of people who contributed.
   * See README.txt for an overview of the Vim source code.
   */
  
  /*
   * vim9script.c: :vim9script, :import, :export and friends
   */
  
  #include "vim.h"
  
  // When not generating protos this is included in proto.h
  #ifdef PROTO
  # include "vim9.h"
  #endif
  
  /*
   * Return TRUE when currently using Vim9 script syntax.
   * Does not go up the stack, a ":function" inside vim9script uses legacy
   * syntax.
   */
      int
  in_vim9script(void)
  {
      // "sc_version" is also set when compiling a ":def" function in legacy
      // script.
      return (current_sctx.sc_version == SCRIPT_VERSION_VIM9
  					 || (cmdmod.cmod_flags & CMOD_VIM9CMD))
  		&& !(cmdmod.cmod_flags & CMOD_LEGACY);
  }
  
  #if defined(FEAT_EVAL) || defined(PROTO)
  /*
   * Return TRUE when currently in a script with script version smaller than
   * "max_version" or command modifiers forced it.
   */
      int
  in_old_script(int max_version)
  {
      return (current_sctx.sc_version < max_version
  					&& !(cmdmod.cmod_flags & CMOD_VIM9CMD))
  		|| (cmdmod.cmod_flags & CMOD_LEGACY);
  }
  
  /*
   * Return TRUE if the current script is Vim9 script.
   * This also returns TRUE in a legacy function in a Vim9 script.
   */
      int
  current_script_is_vim9(void)
  {
      return SCRIPT_ID_VALID(current_sctx.sc_sid)
  	    && SCRIPT_ITEM(current_sctx.sc_sid)->sn_version
  						       == SCRIPT_VERSION_VIM9;
  }
  #endif
  
  #ifdef FEAT_EVAL
  /*
   * Clear Vim9 script-local variables and functions.
   */
      void
  clear_vim9_scriptlocal_vars(int sid)
  {
      hashtab_T	*ht = &SCRIPT_VARS(sid);
  
      hashtab_free_contents(ht);
      hash_init(ht);
      delete_script_functions(sid);
  
      // old imports and script variables are no longer valid
      free_imports_and_script_vars(sid);
  }
  #endif
  
  /*
   * ":vim9script".
   */
      void
  ex_vim9script(exarg_T *eap UNUSED)
  {
  #ifdef FEAT_EVAL
      int		    sid = current_sctx.sc_sid;
      scriptitem_T    *si;
      int		    found_noclear = FALSE;
      char_u	    *p;
  
      if (!sourcing_a_script(eap))
      {
  	emsg(_(e_vim9script_can_only_be_used_in_script));
  	return;
      }
  
      si = SCRIPT_ITEM(sid);
      if (si->sn_state == SN_STATE_HAD_COMMAND)
      {
  	emsg(_(e_vim9script_must_be_first_command_in_script));
  	return;
      }
  
      for (p = eap->arg; !IS_WHITE_OR_NUL(*p); p = skipwhite(skiptowhite(p)))
      {
  	if (STRNCMP(p, "noclear", 7) == 0 && IS_WHITE_OR_NUL(p[7]))
  	{
  	    if (found_noclear)
  	    {
  		semsg(_(e_duplicate_argument_str), p);
  		return;
  	    }
  	    found_noclear = TRUE;
  	}
  	else
  	{
  	    semsg(_(e_invalid_argument_str), eap->arg);
  	    return;
  	}
      }
  
      if (si->sn_state == SN_STATE_RELOAD && !found_noclear)
  	// Reloading a script without the "noclear" argument: clear
  	// script-local variables and functions.
  	clear_vim9_scriptlocal_vars(sid);
      si->sn_state = SN_STATE_HAD_COMMAND;
  
      // Store the prefix with the script, it is used to find exported functions.
      if (si->sn_autoload_prefix == NULL)
  	si->sn_autoload_prefix = get_autoload_prefix(si);
  
      current_sctx.sc_version = SCRIPT_VERSION_VIM9;
      si->sn_version = SCRIPT_VERSION_VIM9;
  
      if (STRCMP(p_cpo, CPO_VIM) != 0)
      {
  	si->sn_save_cpo = vim_strsave(p_cpo);
  	set_option_value((char_u *)"cpo", 0L, (char_u *)CPO_VIM, OPT_NO_REDRAW);
      }
  #else
      // No check for this being the first command, it doesn't matter.
      current_sctx.sc_version = SCRIPT_VERSION_VIM9;
  #endif
  }
  
  #if defined(FEAT_EVAL) || defined(PROTO)
  /*
   * When in Vim9 script give an error and return FAIL.
   */
      int
  not_in_vim9(exarg_T *eap)
  {
      if (in_vim9script())
  	switch (eap->cmdidx)
  	{
  	    case CMD_k:
  		if (eap->addr_count > 0)
  		{
  		    emsg(_(e_no_range_allowed));
  		    return FAIL;
  		}
  		// FALLTHROUGH
  	    case CMD_append:
  	    case CMD_change:
  	    case CMD_insert:
  	    case CMD_open:
  	    case CMD_t:
  	    case CMD_xit:
  		semsg(_(e_command_not_supported_in_vim9_script_missing_var_str), eap->cmd);
  		return FAIL;
  	    default: break;
  	}
      return OK;
  }
  
  /*
   * Give an error message if "p" points at "#{" and return TRUE.
   * This avoids that using a legacy style #{} dictionary leads to difficult to
   * understand errors.
   */
      int
  vim9_bad_comment(char_u *p)
  {
      if (p[0] == '#' && p[1] == '{' && p[2] != '{')
      {
  	emsg(_(e_cannot_use_hash_curly_to_start_comment));
  	return TRUE;
      }
      return FALSE;
  }
  #endif
  
  /*
   * Return TRUE if "p" points at a "#" not followed by one '{'.
   * Does not check for white space.
   */
      int
  vim9_comment_start(char_u *p)
  {
      return p[0] == '#' && (p[1] != '{' || p[2] == '{');
  }
  
  #if defined(FEAT_EVAL) || defined(PROTO)
  
  /*
   * "++nr" and "--nr" commands.
   */
      void
  ex_incdec(exarg_T *eap)
  {
      char_u	*cmd = eap->cmd;
      char_u	*nextcmd = eap->nextcmd;
      size_t	len = STRLEN(eap->cmd) + 8;
  
      if (VIM_ISWHITE(cmd[2]))
      {
  	semsg(_(e_no_white_space_allowed_after_str_str),
  			 eap->cmdidx == CMD_increment ? "++" : "--", eap->cmd);
  	return;
      }
  
      // This works like "nr += 1" or "nr -= 1".
      // Add a '|' to avoid looking in the next line.
      eap->cmd = alloc(len);
      if (eap->cmd == NULL)
  	return;
      vim_snprintf((char *)eap->cmd, len, "%s %c= 1 |", cmd + 2,
  				     eap->cmdidx == CMD_increment ? '+' : '-');
      eap->arg = eap->cmd;
      eap->cmdidx = CMD_var;
      eap->nextcmd = NULL;
      ex_let(eap);
      vim_free(eap->cmd);
      eap->cmd = cmd;
      eap->nextcmd = nextcmd;
  }
  
  /*
   * ":export let Name: type"
   * ":export const Name: type"
   * ":export def Name(..."
   * ":export class Name ..."
   */
      void
  ex_export(exarg_T *eap)
  {
      int	    prev_did_emsg = did_emsg;
  
      if (!in_vim9script())
      {
  	emsg(_(e_export_can_only_be_used_in_vim9script));
  	return;
      }
  
      eap->cmd = eap->arg;
      (void)find_ex_command(eap, NULL, lookup_scriptitem, NULL);
      switch (eap->cmdidx)
      {
  	case CMD_var:
  	case CMD_final:
  	case CMD_const:
  	case CMD_def:
  	case CMD_function:
  	// case CMD_class:
  	    is_export = TRUE;
  	    do_cmdline(eap->cmd, eap->getline, eap->cookie,
  						DOCMD_VERBOSE + DOCMD_NOWAIT);
  
  	    // The command will reset "is_export" when exporting an item.
  	    if (is_export)
  	    {
  		if (did_emsg == prev_did_emsg)
  		    emsg(_(e_export_with_invalid_argument));
  		is_export = FALSE;
  	    }
  	    break;
  	default:
  	    if (did_emsg == prev_did_emsg)
  		emsg(_(e_invalid_command_after_export));
  	    break;
      }
  }
  
  /*
   * Add a new imported item entry to the current script.
   */
      static imported_T *
  new_imported(garray_T *gap)
  {
      if (ga_grow(gap, 1) == OK)
  	return ((imported_T *)gap->ga_data + gap->ga_len++);
      return NULL;
  }
  
  /*
   * Free the script variables from "sn_all_vars".
   */
      static void
  free_all_script_vars(scriptitem_T *si)
  {
      int		todo;
      hashtab_T	*ht = &si->sn_all_vars.dv_hashtab;
      hashitem_T	*hi;
      sallvar_T	*sav;
      sallvar_T	*sav_next;
      int		idx;
  
      hash_lock(ht);
      todo = (int)ht->ht_used;
      for (hi = ht->ht_array; todo > 0; ++hi)
      {
  	if (!HASHITEM_EMPTY(hi))
  	{
  	    --todo;
  
  	    // Free the variable.  Don't remove it from the hashtab, ht_array
  	    // might change then.  hash_clear() takes care of it later.
  	    sav = HI2SAV(hi);
  	    while (sav != NULL)
  	    {
  		sav_next = sav->sav_next;
  		if (sav->sav_di == NULL)
  		    clear_tv(&sav->sav_tv);
  		vim_free(sav);
  		sav = sav_next;
  	    }
  	}
      }
      hash_clear(ht);
      hash_init(ht);
  
      for (idx = 0; idx < si->sn_var_vals.ga_len; ++idx)
      {
  	svar_T    *sv = ((svar_T *)si->sn_var_vals.ga_data) + idx;
  
  	if (sv->sv_type_allocated)
  	    free_type(sv->sv_type);
      }
      ga_clear(&si->sn_var_vals);
  
      // existing commands using script variable indexes are no longer valid
      si->sn_script_seq = current_sctx.sc_seq;
  }
  
  /*
   * Free all imported items in script "sid".
   */
      void
  free_imports_and_script_vars(int sid)
  {
      scriptitem_T    *si = SCRIPT_ITEM(sid);
      int		    idx;
  
      for (idx = 0; idx < si->sn_imports.ga_len; ++idx)
      {
  	imported_T *imp = ((imported_T *)si->sn_imports.ga_data) + idx;
  
  	vim_free(imp->imp_name);
      }
      ga_clear(&si->sn_imports);
  
      free_all_script_vars(si);
  
      clear_type_list(&si->sn_type_list);
  }
  
  /*
   * Mark all imports as possible to redefine.  Used when a script is loaded
   * again but not cleared.
   */
      void
  mark_imports_for_reload(int sid)
  {
      scriptitem_T    *si = SCRIPT_ITEM(sid);
      int		    idx;
  
      for (idx = 0; idx < si->sn_imports.ga_len; ++idx)
      {
  	imported_T *imp = ((imported_T *)si->sn_imports.ga_data) + idx;
  
  	imp->imp_flags |= IMP_FLAGS_RELOAD;
      }
  }
  
  /*
   * Part of "import" that handles a relative or absolute file name/
   * Returns OK or FAIL.
   */
      static int
  handle_import_fname(char_u *fname, int is_autoload, int *sid)
  {
      if (is_autoload)
      {
  	scriptitem_T	*si;
  
  	*sid = find_script_by_name(fname);
  	if (*sid < 0)
  	{
  	    int error = OK;
  
  	    // Script does not exist yet, check name and create a new
  	    // scriptitem.
  	    if (!file_is_readable(fname))
  	    {
  		semsg(_(mch_isdir(fname) ? e_str_is_directory
  					  : e_cannot_read_from_str_2), fname);
  		return FAIL;
  	    }
  	    *sid = get_new_scriptitem_for_fname(&error, fname);
  	    if (error == FAIL)
  		return FAIL;
  	}
  
  	si = SCRIPT_ITEM(*sid);
  	si->sn_import_autoload = TRUE;
  
  	if (si->sn_autoload_prefix == NULL)
  	    si->sn_autoload_prefix = get_autoload_prefix(si);
  
  	// with testing override: load autoload script right away
  	if (!override_autoload || si->sn_state != SN_STATE_NOT_LOADED)
  	    return OK;
      }
      return do_source(fname, FALSE, DOSO_NONE, sid);
  }
  
  /*
   * Handle an ":import" command and add the resulting imported_T to "gap", when
   * not NULL, or script "import_sid" sn_imports.
   * "cctx" is NULL at the script level.
   * Returns a pointer to after the command or NULL in case of failure
   */
      static char_u *
  handle_import(
  	char_u	    *arg_start,
  	garray_T    *gap,
  	int	    import_sid,
  	evalarg_T   *evalarg,
  	void	    *cctx)
  {
      char_u	*arg = arg_start;
      char_u	*nextarg;
      int		is_autoload = FALSE;
      int		getnext;
      char_u	*expr_end;
      int		ret = FAIL;
      char_u	*as_name = NULL;
      typval_T	tv;
      int		sid = -2;
      int		res;
      long	start_lnum = SOURCING_LNUM;
      garray_T	*import_gap;
      int		i;
  
      if (STRNCMP(arg, "autoload", 8) == 0 && VIM_ISWHITE(arg[8]))
      {
  	is_autoload = TRUE;
  	arg = skipwhite(arg + 8);
      }
  
      // The name of the file can be an expression, which must evaluate to a
      // string.
      ret = eval0_retarg(arg, &tv, NULL, evalarg, &expr_end);
      if (ret == FAIL)
  	goto erret;
      if (tv.v_type != VAR_STRING
  		       || tv.vval.v_string == NULL || *tv.vval.v_string == NUL)
      {
  	semsg(_(e_invalid_string_for_import_str), arg);
  	goto erret;
      }
  
      // Give error messages for the start of the line.
      SOURCING_LNUM = start_lnum;
  
      /*
       * find script file
       */
      if (*tv.vval.v_string == '.')
      {
  	size_t		len;
  	scriptitem_T	*si = SCRIPT_ITEM(current_sctx.sc_sid);
  	char_u		*tail = gettail(si->sn_name);
  	char_u		*from_name;
  
  	// Relative to current script: "./name.vim", "../../name.vim".
  	len = STRLEN(si->sn_name) - STRLEN(tail) + STRLEN(tv.vval.v_string) + 2;
  	from_name = alloc((int)len);
  	if (from_name == NULL)
  	    goto erret;
  	vim_strncpy(from_name, si->sn_name, tail - si->sn_name);
  	add_pathsep(from_name);
  	STRCAT(from_name, tv.vval.v_string);
  	simplify_filename(from_name);
  
  	res = handle_import_fname(from_name, is_autoload, &sid);
  	vim_free(from_name);
      }
      else if (mch_isFullName(tv.vval.v_string)
  #ifdef BACKSLASH_IN_FILENAME
  	    // On MS-Windows omitting the drive is still handled like an
  	    // absolute path, not using 'runtimepath'.
  	    || *tv.vval.v_string == '/' || *tv.vval.v_string == '\\'
  #endif
  	    )
      {
  	// Absolute path: "/tmp/name.vim"
  	res = handle_import_fname(tv.vval.v_string, is_autoload, &sid);
      }
      else if (is_autoload)
      {
  	size_t	    len = 9 + STRLEN(tv.vval.v_string) + 1;
  	char_u	    *from_name;
  
  	// Find file in "autoload" subdirs in 'runtimepath'.
  	from_name = alloc((int)len);
  	if (from_name == NULL)
  	    goto erret;
  	vim_snprintf((char *)from_name, len, "autoload/%s", tv.vval.v_string);
  	// we need a scriptitem without loading the script
  	sid = find_script_in_rtp(from_name);
  	vim_free(from_name);
  	if (SCRIPT_ID_VALID(sid))
  	{
  	    scriptitem_T    *si = SCRIPT_ITEM(sid);
  
  	    if (si->sn_autoload_prefix == NULL)
  		si->sn_autoload_prefix = get_autoload_prefix(si);
  	    res = OK;
  	    if (override_autoload && si->sn_state == SN_STATE_NOT_LOADED)
  		// testing override: load autoload script right away
  		(void)do_source(si->sn_name, FALSE, DOSO_NONE, NULL);
  	}
  	else
  	    res = FAIL;
      }
      else
      {
  	size_t	    len = 7 + STRLEN(tv.vval.v_string) + 1;
  	char_u	    *from_name;
  
  	// Find file in "import" subdirs in 'runtimepath'.
  	from_name = alloc((int)len);
  	if (from_name == NULL)
  	    goto erret;
  	vim_snprintf((char *)from_name, len, "import/%s", tv.vval.v_string);
  	res = source_in_path(p_rtp, from_name, DIP_NOAFTER, &sid);
  	vim_free(from_name);
      }
  
      if (res == FAIL || sid <= 0)
      {
  	semsg(_(is_autoload && sid == -2
  		    ? e_autoload_import_cannot_use_absolute_or_relative_path
  		    : e_could_not_import_str), tv.vval.v_string);
  	goto erret;
      }
  
      if (sid == current_sctx.sc_sid)
      {
  	emsg(_(e_script_cannot_import_itself));
  	goto erret;
      }
  
      import_gap = gap != NULL ? gap : &SCRIPT_ITEM(import_sid)->sn_imports;
      for (i = 0; i < import_gap->ga_len; ++i)
      {
  	imported_T *import = (imported_T *)import_gap->ga_data + i;
  
  	if (import->imp_sid == sid)
  	{
  	    if (import->imp_flags & IMP_FLAGS_RELOAD)
  	    {
  		// encountering same script first time on a reload is OK
  		import->imp_flags &= ~IMP_FLAGS_RELOAD;
  		break;
  	    }
  	    semsg(_(e_cannot_import_same_script_twice_str), tv.vval.v_string);
  	    goto erret;
  	}
      }
  
      // Allow for the "as Name" to be in the next line.
      nextarg = eval_next_non_blank(expr_end, evalarg, &getnext);
      if (STRNCMP("as", nextarg, 2) == 0 && IS_WHITE_OR_NUL(nextarg[2]))
      {
  	char_u *p;
  
  	if (getnext)
  	    arg = eval_next_line(evalarg);
  	else
  	    arg = nextarg;
  
  	// Skip over "as Name "; no line break allowed after "as".
  	// Do not allow for ':' and '#'.
  	arg = skipwhite(arg + 2);
  	p = arg;
  	if (eval_isnamec1(*arg))
  	    while (ASCII_ISALNUM(*arg) || *arg == '_')
  		++arg;
  	if (p == arg || !IS_WHITE_OR_NUL(*arg))
  	{
  	    semsg(_(e_syntax_error_in_import_str), p);
  	    goto erret;
  	}
  	as_name = vim_strnsave(p, arg - p);
  	arg = skipwhite(arg);
      }
      else
      {
  	char_u *p = gettail(tv.vval.v_string);
  	char_u *end = (char_u *)strstr((char *)p, ".vim");
  
  	if (!ends_excmd2(arg_start, expr_end))
  	{
  	    semsg(_(e_trailing_characters_str), expr_end);
  	    goto erret;
  	}
  	if (end == NULL || end[4] != NUL)
  	{
  	    semsg(_(e_imported_script_must_use_as_or_end_in_dot_vim_str), p);
  	    goto erret;
  	}
  	if (end == p)
  	{
  	    semsg(_(e_cannot_import_dot_vim_without_using_as), p);
  	    goto erret;
  	}
  	as_name = vim_strnsave(p, end - p);
      }
  
      if (as_name != NULL)
      {
  	imported_T  *imported;
  
  	imported = find_imported(as_name, STRLEN(as_name), FALSE);
  	if (imported != NULL && imported->imp_sid != sid)
  	{
  	    semsg(_(e_name_already_defined_str), as_name);
  	    goto erret;
  	}
  	else if (imported == NULL
  		&& check_defined(as_name, STRLEN(as_name), cctx, NULL,
  								FALSE) == FAIL)
  	    goto erret;
  
  	if (imported == NULL)
  	{
  	    imported = new_imported(import_gap);
  	    if (imported == NULL)
  		goto erret;
  	    imported->imp_name = as_name;
  	    as_name = NULL;
  	    imported->imp_sid = sid;
  	    if (is_autoload)
  		imported->imp_flags = IMP_FLAGS_AUTOLOAD;
  	}
      }
  
  erret:
      clear_tv(&tv);
      vim_free(as_name);
      return arg;
  }
  
  /*
   * ":import 'filename'"
   * ":import 'filename' as Name"
   */
      void
  ex_import(exarg_T *eap)
  {
      char_u	*cmd_end;
      evalarg_T	evalarg;
  
      if (!sourcing_a_script(eap))
      {
  	emsg(_(e_import_can_only_be_used_in_script));
  	return;
      }
      fill_evalarg_from_eap(&evalarg, eap, eap->skip);
  
      cmd_end = handle_import(eap->arg, NULL, current_sctx.sc_sid,
  							       &evalarg, NULL);
      if (cmd_end != NULL)
  	set_nextcmd(eap, cmd_end);
      clear_evalarg(&evalarg, eap);
  }
  
  /*
   * Find an exported item in "sid" matching "name".
   * Either "cctx" or "cstack" is NULL.
   * When it is a variable return the index.
   * When it is a user function return "*ufunc".
   * When not found returns -1 and "*ufunc" is NULL.
   */
      int
  find_exported(
  	int	    sid,
  	char_u	    *name,
  	ufunc_T	    **ufunc,
  	type_T	    **type,
  	cctx_T	    *cctx,
  	cstack_T    *cstack,
  	int	    verbose)
  {
      int		idx = -1;
      svar_T	*sv;
      scriptitem_T *script = SCRIPT_ITEM(sid);
  
      if (script->sn_import_autoload && script->sn_state == SN_STATE_NOT_LOADED)
      {
  	if (do_source(script->sn_name, FALSE, DOSO_NONE, NULL) == FAIL)
  	    return -1;
      }
  
      // Find name in "script".
      idx = get_script_item_idx(sid, name, 0, cctx, cstack);
      if (idx >= 0)
      {
  	sv = ((svar_T *)script->sn_var_vals.ga_data) + idx;
  	*ufunc = NULL;
  	if (!sv->sv_export)
  	{
  	    if (verbose)
  		semsg(_(e_item_not_exported_in_script_str), name);
  	    return -1;
  	}
  	*type = sv->sv_type;
      }
      else
      {
  	size_t	len = STRLEN(name);
  	char_u	buffer[200];
  	char_u	*funcname;
  
  	// It could be a user function.  Normally this is stored as
  	// "<SNR>99_name".  For an autoload script a function is stored with
  	// the autoload prefix: "dir#script#name".
  	if (script->sn_autoload_prefix != NULL)
  	    len += STRLEN(script->sn_autoload_prefix) + 2;
  	else
  	    len += 15;
  
  	if (len < sizeof(buffer))
  	    funcname = buffer;
  	else
  	{
  	    funcname = alloc(len);
  	    if (funcname == NULL)
  		return -1;
  	}
  	if (script->sn_autoload_prefix != NULL)
  	{
  	    sprintf((char *)funcname, "%s%s", script->sn_autoload_prefix, name);
  	}
  	else
  	{
  	    funcname[0] = K_SPECIAL;
  	    funcname[1] = KS_EXTRA;
  	    funcname[2] = (int)KE_SNR;
  	    sprintf((char *)funcname + 3, "%ld_%s", (long)sid, name);
  	}
  	*ufunc = find_func(funcname, FALSE);
  
  	if (*ufunc == NULL)
  	{
  	    if (verbose)
  	    {
  		ufunc_T *alt_ufunc = NULL;
  
  		if (script->sn_autoload_prefix != NULL)
  		{
  		    // try find the function by the script-local name
  		    funcname[0] = K_SPECIAL;
  		    funcname[1] = KS_EXTRA;
  		    funcname[2] = (int)KE_SNR;
  		    sprintf((char *)funcname + 3, "%ld_%s", (long)sid, name);
  		    alt_ufunc = find_func(funcname, FALSE);
  		}
  		if (alt_ufunc != NULL)
  		    semsg(_(e_item_not_exported_in_script_str), name);
  		else
  		    semsg(_(e_item_not_found_in_script_str), name);
  	    }
  	}
  	else if (((*ufunc)->uf_flags & FC_EXPORT) == 0)
  	{
  	    if (verbose)
  		semsg(_(e_item_not_exported_in_script_str), name);
  	    *ufunc = NULL;
  	}
  	if (funcname != buffer)
  	    vim_free(funcname);
      }
  
      return idx;
  }
  
  /*
   * Declare a script-local variable without init: "let var: type".
   * "const" is an error since the value is missing.
   * Returns a pointer to after the type.
   */
      char_u *
  vim9_declare_scriptvar(exarg_T *eap, char_u *arg)
  {
      char_u	    *p;
      char_u	    *name;
      scriptitem_T    *si = SCRIPT_ITEM(current_sctx.sc_sid);
      type_T	    *type;
      typval_T	    init_tv;
  
      if (eap->cmdidx == CMD_final || eap->cmdidx == CMD_const)
      {
  	if (eap->cmdidx == CMD_final)
  	    emsg(_(e_final_requires_a_value));
  	else
  	    emsg(_(e_const_requires_a_value));
  	return arg + STRLEN(arg);
      }
  
      // Check for valid starting character.
      if (!eval_isnamec1(*arg))
      {
  	semsg(_(e_invalid_argument_str), arg);
  	return arg + STRLEN(arg);
      }
  
      for (p = arg + 1; *p != NUL && eval_isnamec(*p); MB_PTR_ADV(p))
  	if (*p == ':' && (VIM_ISWHITE(p[1]) || p != arg + 1))
  	    break;
  
      if (*p != ':')
      {
  	emsg(_(e_type_or_initialization_required));
  	return arg + STRLEN(arg);
      }
      if (!VIM_ISWHITE(p[1]))
      {
  	semsg(_(e_white_space_required_after_str_str), ":", p);
  	return arg + STRLEN(arg);
      }
      name = vim_strnsave(arg, p - arg);
  
      // parse type, check for reserved name
      p = skipwhite(p + 1);
      type = parse_type(&p, &si->sn_type_list, TRUE);
      if (type == NULL || check_reserved_name(name) == FAIL)
      {
  	vim_free(name);
  	return p;
      }
  
      // Create the variable with 0/NULL value.
      CLEAR_FIELD(init_tv);
      if (type->tt_type == VAR_ANY)
  	// A variable of type "any" is not possible, just use zero instead
  	init_tv.v_type = VAR_NUMBER;
      else
  	init_tv.v_type = type->tt_type;
      set_var_const(name, 0, type, &init_tv, FALSE, ASSIGN_INIT, 0);
  
      vim_free(name);
      return p;
  }
  
  /*
   * Vim9 part of adding a script variable: add it to sn_all_vars (lookup by name
   * with a hashtable) and sn_var_vals (lookup by index).
   * When "create" is TRUE this is a new variable, otherwise find and update an
   * existing variable.
   * "flags" can have ASSIGN_FINAL or ASSIGN_CONST.
   * When "*type" is NULL use "tv" for the type and update "*type".  If
   * "do_member" is TRUE also use the member type, otherwise use "any".
   */
      void
  update_vim9_script_var(
  	int	    create,
  	dictitem_T  *di,
  	char_u	    *name,
  	int	    flags,
  	typval_T    *tv,
  	type_T	    **type,
  	int	    do_member)
  {
      scriptitem_T    *si = SCRIPT_ITEM(current_sctx.sc_sid);
      hashitem_T	    *hi;
      svar_T	    *sv = NULL;
  
      if (create)
      {
  	sallvar_T   *newsav;
  	sallvar_T   *sav = NULL;
  
  	// Store a pointer to the typval_T, so that it can be found by index
  	// instead of using a hastab lookup.
  	if (ga_grow(&si->sn_var_vals, 1) == FAIL)
  	    return;
  
  	hi = hash_find(&si->sn_all_vars.dv_hashtab, name);
  	if (!HASHITEM_EMPTY(hi))
  	{
  	    // Variable with this name exists, either in this block or in
  	    // another block.
  	    for (sav = HI2SAV(hi); ; sav = sav->sav_next)
  	    {
  		if (sav->sav_block_id == si->sn_current_block_id)
  		{
  		    // variable defined in a loop, re-use the entry
  		    sv = ((svar_T *)si->sn_var_vals.ga_data)
  						       + sav->sav_var_vals_idx;
  		    // unhide the variable
  		    if (sv->sv_tv == &sav->sav_tv)
  		    {
  			clear_tv(&sav->sav_tv);
  			sv->sv_tv = &di->di_tv;
  			sav->sav_di = di;
  		    }
  		    break;
  		}
  		if (sav->sav_next == NULL)
  		    break;
  	    }
  	}
  
  	if (sv == NULL)
  	{
  	    // Variable not defined or not defined in current block: Add a
  	    // svar_T and create a new sallvar_T.
  	    sv = ((svar_T *)si->sn_var_vals.ga_data) + si->sn_var_vals.ga_len;
  	    newsav = (sallvar_T *)alloc_clear(
  				       sizeof(sallvar_T) + STRLEN(name));
  	    if (newsav == NULL)
  		return;
  
  	    sv->sv_tv = &di->di_tv;
  	    sv->sv_const = (flags & ASSIGN_FINAL) ? ASSIGN_FINAL
  				   : (flags & ASSIGN_CONST) ? ASSIGN_CONST : 0;
  	    sv->sv_export = is_export;
  	    newsav->sav_var_vals_idx = si->sn_var_vals.ga_len;
  	    ++si->sn_var_vals.ga_len;
  	    STRCPY(&newsav->sav_key, name);
  	    sv->sv_name = newsav->sav_key;
  	    newsav->sav_di = di;
  	    newsav->sav_block_id = si->sn_current_block_id;
  
  	    if (HASHITEM_EMPTY(hi))
  		// new variable name
  		hash_add(&si->sn_all_vars.dv_hashtab, newsav->sav_key);
  	    else if (sav != NULL)
  		// existing name in a new block, append to the list
  		sav->sav_next = newsav;
  	}
      }
      else
      {
  	sv = find_typval_in_script(&di->di_tv, 0);
      }
      if (sv != NULL)
      {
  	if (*type == NULL)
  	    *type = typval2type(tv, get_copyID(), &si->sn_type_list,
  					       do_member ? TVTT_DO_MEMBER : 0);
  	else if ((flags & ASSIGN_INIT) == 0
  		&& (*type)->tt_type == VAR_BLOB && tv->v_type == VAR_BLOB
  						    && tv->vval.v_blob == NULL)
  	{
  	    // "var b: blob = null_blob" has a different type.
  	    *type = &t_blob_null;
  	}
  	if (sv->sv_type_allocated)
  	    free_type(sv->sv_type);
  	if (*type != NULL && ((*type)->tt_type == VAR_FUNC
  					   || (*type)->tt_type == VAR_PARTIAL))
  	{
  	    // The type probably uses uf_type_list, which is cleared when the
  	    // function is freed, but the script variable may keep the type.
  	    // Make a copy to avoid using freed memory.
  	    sv->sv_type = alloc_type(*type);
  	    sv->sv_type_allocated = TRUE;
  	}
  	else
  	{
  	    sv->sv_type = *type;
  	    sv->sv_type_allocated = FALSE;
  	}
      }
  
      // let ex_export() know the export worked.
      is_export = FALSE;
  }
  
  /*
   * Hide a script variable when leaving a block.
   * "idx" is de index in sn_var_vals.
   * When "func_defined" is non-zero then a function was defined in this block,
   * the variable may be accessed by it.  Otherwise the variable can be cleared.
   */
      void
  hide_script_var(scriptitem_T *si, int idx, int func_defined)
  {
      svar_T	*sv = ((svar_T *)si->sn_var_vals.ga_data) + idx;
      hashtab_T	*script_ht = get_script_local_ht();
      hashtab_T	*all_ht = &si->sn_all_vars.dv_hashtab;
      hashitem_T	*script_hi;
      hashitem_T	*all_hi;
  
      // Remove a variable declared inside the block, if it still exists.
      // If it was added in a nested block it will already have been removed.
      // The typval is moved into the sallvar_T.
      script_hi = hash_find(script_ht, sv->sv_name);
      all_hi = hash_find(all_ht, sv->sv_name);
      if (!HASHITEM_EMPTY(script_hi) && !HASHITEM_EMPTY(all_hi))
      {
  	dictitem_T	*di = HI2DI(script_hi);
  	sallvar_T	*sav = HI2SAV(all_hi);
  	sallvar_T	*sav_prev = NULL;
  
  	// There can be multiple entries with the same name in different
  	// blocks, find the right one.
  	while (sav != NULL && sav->sav_var_vals_idx != idx)
  	{
  	    sav_prev = sav;
  	    sav = sav->sav_next;
  	}
  	if (sav != NULL)
  	{
  	    if (func_defined)
  	    {
  		// move the typval from the dictitem to the sallvar
  		sav->sav_tv = di->di_tv;
  		di->di_tv.v_type = VAR_UNKNOWN;
  		sav->sav_flags = di->di_flags;
  		sav->sav_di = NULL;
  		sv->sv_tv = &sav->sav_tv;
  	    }
  	    else
  	    {
  		if (sav_prev == NULL)
  		    hash_remove(all_ht, all_hi);
  		else
  		    sav_prev->sav_next = sav->sav_next;
  		sv->sv_name = NULL;
  		vim_free(sav);
  	    }
  	    delete_var(script_ht, script_hi);
  	}
      }
  }
  
  /*
   * Find the script-local variable that links to "dest".
   * If "sid" is zero use the current script.
   * Returns NULL if not found and give an internal error.
   */
      svar_T *
  find_typval_in_script(typval_T *dest, scid_T sid)
  {
      scriptitem_T    *si = SCRIPT_ITEM(sid == 0 ? current_sctx.sc_sid : sid);
      int		    idx;
  
      if (si->sn_version != SCRIPT_VERSION_VIM9)
  	// legacy script doesn't store variable types
  	return NULL;
  
      // Find the svar_T in sn_var_vals.  Start at the end, in a for loop the
      // variable was added at the end.
      for (idx = si->sn_var_vals.ga_len - 1; idx >= 0; --idx)
      {
  	svar_T    *sv = ((svar_T *)si->sn_var_vals.ga_data) + idx;
  
  	// If "sv_name" is NULL the variable was hidden when leaving a block,
  	// don't check "sv_tv" then, it might be used for another variable now.
  	if (sv->sv_name != NULL && sv->sv_tv == dest)
  	    return sv;
      }
      iemsg("find_typval_in_script(): not found");
      return NULL;
  }
  
  /*
   * Check if the type of script variable "dest" allows assigning "value".
   * If needed convert "value" to a bool.
   */
      int
  check_script_var_type(
  	svar_T	    *sv,
  	typval_T    *value,
  	char_u	    *name,
  	where_T	    where)
  {
      int	    ret;
  
      if (sv->sv_const != 0)
      {
  	semsg(_(e_cannot_change_readonly_variable_str), name);
  	return FAIL;
      }
      ret = check_typval_type(sv->sv_type, value, where);
      if (ret == OK && need_convert_to_bool(sv->sv_type, value))
      {
  	int	val = tv2bool(value);
  
  	clear_tv(value);
  	value->v_type = VAR_BOOL;
  	value->v_lock = 0;
  	value->vval.v_number = val ? VVAL_TRUE : VVAL_FALSE;
      }
      return ret;
  }
  
  // words that cannot be used as a variable
  static char *reserved[] = {
      "true",
      "false",
      "null",
      "null_blob",
      "null_dict",
      "null_function",
      "null_list",
      "null_partial",
      "null_string",
      "null_channel",
      "null_job",
      "this",
      NULL
  };
  
      int
  check_reserved_name(char_u *name)
  {
      int idx;
  
      for (idx = 0; reserved[idx] != NULL; ++idx)
  	if (STRCMP(reserved[idx], name) == 0)
  	{
  	    semsg(_(e_cannot_use_reserved_name), name);
  	    return FAIL;
  	}
      return OK;
  }
  
  #endif // FEAT_EVAL
  