## Copyright (C) 1996-2012 Kurt Hornik
##
## 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
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {Function File} {} 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

## Author: John Swensen <jpswensen@jhu.edu>

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

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