########################################################################
##
## Copyright (C) 1996-2022 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.
##
## Octave 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.
##
## Octave 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 Octave; see the file COPYING.  If not, see
## <https://www.gnu.org/licenses/>.
##
########################################################################

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

## This function was derived from deblank.

function s = strtrim (s)

  if (nargin < 1)
    print_usage ();
  endif

  if (ischar (s))

    k = find (! isspace (s));
    if (isempty (s) || isempty (k))
      s = "";
    else
      s = s(:, ceil (min (k) / rows (s)):ceil (max (k) / rows (s)));
    endif

  elseif (iscell (s))

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

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

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

endfunction


%!assert (strtrim ("    abc  "), "abc")
%!assert (strtrim ("  "), "")
%!assert (strtrim ("abc"), "abc")
%!assert (strtrim (char (" abc   ", "   def   ")), ["abc  "; "  def"])
%!assert (strtrim ({" abc   "; "   def   "}), {"abc"; "def"})
%!assert (strtrim ({" abc   ", {"   def   "}}), {"abc", {"def"}})

%!error <Invalid call to strtrim> strtrim ()
%!error <called with too many inputs> strtrim ("abc", "def")
%!error <argument must be a string> strtrim (1)
%!error <argument must be a string> strtrim ({[]})