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## -*- texinfo -*-
## @deftypefn {} {@var{s} =} deblank (@var{s})
## Remove trailing whitespace and nulls from @var{s}.
##
## If @var{s} is a matrix, @var{deblank} trims each row to the length of
## the longest string.  If @var{s} is a cell array of strings, operate
## recursively on each string element.
##
## Examples:
##
## @example
## @group
## deblank ("    abc  ")
##      @xresult{}  "    abc"
##
## deblank ([" abc   "; "   def   "])
##      @xresult{}  [" abc  " ; "   def"]
## @end group
## @end example
## @seealso{strtrim}
## @end deftypefn

function s = deblank (s)

  if (nargin != 1)
    print_usage ();
  endif

  if (isempty (s))

    ## Return empty objects unchanged (Matlab compatibility)

  elseif (ischar (s))

    ## Find indices of non-whitespace characters.  If s is a
    ## char matrix, the indices are in column major order.
    k = find (! isspace (s) & s != "\0");
    if (isempty (k))
      ## Even if s was a char matrix! (Matlab compatibility)
      s = "";
    else
      s = s(:,1:ceil (max (k) / rows (s)));
    endif

  elseif (iscell (s))

    char_idx = cellfun ("isclass", s, "char");
    cell_idx = cellfun ("isclass", s, "cell");
    empty_idx = cellfun ("isempty", s);
    if (! all (char_idx | cell_idx | empty_idx))
      error ("deblank: S argument must be a string or cellstring");
    endif

    ## Divide work load.  Recursive cellfun deblank call is slow
    ## and avoided where possible.
    s(char_idx) = regexprep (s(char_idx), "[\\s\v\\0]+$", '');
    s(cell_idx) = cellfun ("deblank", s(cell_idx), "UniformOutput", false);

  else
    error ("deblank: S argument must be a string or cellstring");
  endif

endfunction


%!assert (deblank (" f o o \0"), " f o o")
%!assert (deblank (" \t f o o \t \0"), " \t f o o")
%!assert (deblank (char (" abc   ", "   def   ")), [" abc  " ; "   def"])
%!assert (deblank (["   "; "   "]), "")
%!assert (deblank ('   '), '')
%!assert (deblank ("   "), "")
%!assert (deblank (""), "")
%!assert (deblank ([]), [])
%!assert (deblank ({}), {})
%!assert (deblank ({[]}), {[]})
%!assert (deblank ({[], []}), {[], []})
%!assert (deblank ({" abc   ", {"   def   "}}), {" abc", {"   def"}})

%!error <Invalid call to deblank> deblank ()
%!error <called with too many inputs> deblank ("foo", "bar")
%!error <argument must be a string> deblank (1)
