use exceptions for better invalid index error reporting (bug #45957) * lo-array-gripes.h, lo-array-gripes.cc (index_exception): New base class for indexing errors. (invalid_index, out_of_range): New classes. (gripe_index_out_of_range): New overloaded function. (gripe_invalid_index): New overloaded functions. Delete version with no arguments. (gripe_invalid_assignment_size, gripe_assignment_dimension_mismatch): Delete. Change uses of gripe functions as needed. * Cell.cc (Cell::index, Cell::assign, Cell::delete_elements): Use exceptions to collect error info about and handle indexing errors. * data.cc (Fnth_element, do_accumarray_sum, F__accumarray_sum__, do_accumarray_minmax, do_accumarray_minmax_fun, F__accumdim_sum__): Likewise. * oct-map.cc (octave_map::index, octave_map::assign, octave_map::delete_elements): Likewise. * sparse.cc (Fsparse): Likewise. * sub2ind.cc (Fsub2ind, Find2sub): Likewise. New tests. * utils.cc (dims_to_numel): Likewise. * ov-base-diag.cc (octave_base_diag<DMT, MT>::do_index_op, octave_base_diag<DMT, MT>::subsasgn): Likewise. * ov-base-mat.cc (octave_base_matrix<MT>::subsref, octave_base_matrix<MT>::assign): Likewise. * ov-base-sparse.cc (octave_base_sparse<T>::do_index_op, octave_base_sparse<T>::assign, octave_base_sparse<MT>::delete_elements): Likewise. * ov-classdef.cc (cdef_object_array::subsref, cdef_object_array::subsasgn): Likewise. * ov-java.cc (make_java_index): Likewise. * ov-perm.cc (octave_perm_matrix::do_index_op): Likewise. * ov-range.cc (octave_range::do_index_op): Likewise. * ov-re-diag.cc (octave_diag_matrix::do_index_op): Likewise. * ov-str-mat.cc (octave_char_matrix_str::do_index_op_internal): Likewise. * pt-assign.cc (tree_simple_assignment::rvalue1): Likewise. * pt-idx.cc (tree_index_expression::rvalue, tree_index_expression::lvalue): Likewise. * Array-util.cc (sub2ind): Likewise. * toplev.cc (main_loop): Also catch unhandled index_exception exceptions. * ov-base.cc (octave_base_value::index_vector): Improve error message. * ov-re-sparse.cc (octave_sparse_matrix::index_vector): Likewise. * ov-complex.cc (complex_index): New class. (gripe_complex_index): New function. (octave_complex::index_vector): Use it. * pt-id.h, pt-id.cc (tree_identifier::is_variable, tree_black_hole::is_variable): Now const. * pt-idx.cc (final_index_error): New static function. (tree_index_expression::rvalue, tree_index_expression::lvalue): Use it. * index.tst: New tests.

## Copyright (C) 2006-2015 John W. Eaton
##
## 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/>.

%!test
%! i = 0;
%! while (eye (2))
%!   i++;
%!   __printf_assert__ ("%d\n", i);
%! end  # "end" is part of test, check not using "endwhile"
%! assert (__prog_output_assert__ (""));

%!test
%! i = 5;
%! while (--i)
%!   __printf_assert__ ("%d", i);
%! endwhile
%! __printf_assert__ ("\n");
%! assert (__prog_output_assert__ ("4321"));

%!test
%! i = 5;
%! while (i)
%!   i--;
%!   __printf_assert__ ("%d", i);
%! endwhile
%! __printf_assert__ ("\n");
%! assert (__prog_output_assert__ ("43210"));

%!test
%! i = 0;
%! while (i++ < 20)
%!   if (i > 2)
%!     break;
%!   endif
%!   __printf_assert__ ("%d", i);
%! endwhile
%! __printf_assert__ ("\n");
%! assert (__prog_output_assert__ ("12"));

%!test
%! i = 0;
%! while (++i < 5)
%!   if (i < 3)
%!     continue;
%!   endif
%!   __printf_assert__ ("%d", i);
%! endwhile
%! __printf_assert__ ("\n");
%! assert (__prog_output_assert__ ("34"));

%% test parsing of single-quoted character string appearing immediately
%% after a while condition.
%!test
%! i = 0;
%! while (++i < 5)
%!   'foo';
%! endwhile
%! assert (i, 5);