## Copyright (C) 1995, 1996  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 2, 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, write to the Free
## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.

## usage:  strrep (s, x, y)
##
## Replace all occurences of the substring x of the string s with the
## string y.

## Author: Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>
## Created: 11 November 1994
## Adapted-By: jwe

function t = strrep (s, x, y)

  if (nargin <> 3)
    usage ("strrep (s, x, y)");
  endif

  if (! (isstr (s) && isstr (x) && isstr (y)))
    error ("strrep: all arguments must be strings");
  endif

  if (length (x) > length (s) || isempty (x))
    t = s;
    return;
  endif

  ind = findstr (s, x, 0);
  len = length (ind);
  if (len == 0)
    t = s;
  else
    save_empty_list_elements_ok = empty_list_elements_ok;
    unwind_protect
      empty_list_elements_ok = 1;
      l_x = length (x);
      tmp = s (1 : ind (1) - 1);
      t = strcat (tmp, y);
      for k = 1 : len - 1
      	tmp = s (ind (k) + l_x : ind (k+1) - 1);
      	t = strcat (t, tmp, y);
      endfor
      tmp = s (ind(len) + l_x : length (s));
      t = [t, tmp];
    unwind_protect_cleanup
      empty_list_elements_ok = save_empty_list_elements_ok;
    end_unwind_protect
  endif

endfunction