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## Copyright (C) 2019-2021 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## This file is part of Octave.
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## Octave is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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## along with Octave; see the file COPYING.  If not, see
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########################################################################

## -*- texinfo -*-
## @deftypefn {} {} mustBeMember (@var{x}, @var{valid})
##
## Require that input @var{x} is a member of a set of given valid values.
##
## Raise an error if any element of the input @var{x} is not a member
## of the set @var{valid}, as determined by @code{ismember (@var{x})}.
##
## Programming Note: char inputs may behave strangely because of the
## interaction between chars and cellstrings when calling @code{ismember} on
## them.  But it will probably "do what you mean" if you just use it naturally.
## To guarantee operation, convert all char arrays to cellstrings with
## @code{cellstr}.
##
## @seealso{mustBeNonempty, ismember}
## @end deftypefn

function mustBeMember (x, valid)

  if (nargin != 2)
    print_usage ();
  endif

  tf = ! (ismember (x, valid))(:);
  if (any (tf))
    label = inputname (1);
    if (isempty (label))
      label = "input";
    endif
    n_bad = numel (find (tf));
    # FIXME: Fancy inclusion of bad_val & valid values in the error message.
    #        Probably use mat2str() in a try/catch for that.
    error ("%s must be one of the specified valid values; found %d elements that were not", ...
           label, n_bad);
  endif

endfunction


%!test
%! mustBeMember (42, 38:50);
%! mustBeMember ("foo", {"foo", "bar", "baz"});
%! mustBeMember (38:42, 37:43);
%! mustBeMember ({"foo","bar"}, {"foo", "bar", "baz"});

%!error <Invalid call> mustBeMember ()
%!error <Invalid call> mustBeMember (1)
%!error <Invalid call> mustBeMember (1,2,3)
%!error <found 1 elements> mustBeMember ([1, 42], 1:5)
%!error <found 1 elements> mustBeMember ("nope", {"foo", "bar", "baz"})
