## Copyright (C) 2019, 2023, 2024, 2026 Andrew Janke
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; If not, see <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {Function File} {@code{x} =} mustBeCellstr (@var{x}, @var{label})
##
## Requires that input is a cellstr.
##
## Raises an error if the input @var{x} is not a cellstr (a cell array
## of @code{char} arrays).
##
## TODO: Decide whether to require the contained char arrays be rowvec/empty.
##
## @var{label} is an optional input that determines how the input will be described in
## error messages. If not supplied, @code{inputname (1)} is used, and if that is
## empty, it falls back to "input".
##
## @end deftypefn

function mustBeCellstr (x, label)
  if (nargin < 2); label = []; endif
  if (! iscellstr (x))
    if (isempty (label))
      label = inputname (1);
    endif
    if (isempty (label))
      label = "input";
    endif
    if (iscell (x))
      el_classes = cellfun (@(e) {class(e)}, x);
      type_descr = sprintf ("cell array containing %s", strjoin (el_classes, ", "));
    else
      type_descr = class (x);
    endif
    error ("%s must be a cellstr; got a %s", ...
      label, type_descr);
  endif
endfunction
