## Copyright (C) 2000-2011 Paul Kienzle
##
## 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} {} assert (@var{cond})
## @deftypefnx {Function File} {} assert (@var{cond}, @var{errmsg}, @dots{})
## @deftypefnx {Function File} {} assert (@var{cond}, @var{msg_id}, @var{errmsg}, @dots{})
## @deftypefnx {Function File} {} assert (@var{observed}, @var{expected})
## @deftypefnx {Function File} {} assert (@var{observed}, @var{expected}, @var{tol})
##
## Produces an error if the condition is not met.  @code{assert} can be
## called in three different ways.
##
## @table @code
## @item assert (@var{cond})
## @itemx assert (@var{cond}, @var{errmsg}, @dots{})
## @itemx assert (@var{cond}, @var{msg_id}, @var{errmsg}, @dots{})
## Called with a single argument @var{cond}, @code{assert} produces an
## error if @var{cond} is zero.  If called with a single argument a
## generic error message.  With more than one argument, the additional
## arguments are passed to the @code{error} function.
##
## @item assert (@var{observed}, @var{expected})
## Produce an error if observed is not the same as expected.  Note that
## observed and expected can be strings, scalars, vectors, matrices,
## lists or structures.
##
## @item assert(@var{observed}, @var{expected}, @var{tol})
## Accept a tolerance when comparing numbers.
## If @var{tol} is positive use it as an absolute tolerance, will produce an
## error if
## @code{abs(@var{observed} - @var{expected}) > abs(@var{tol})}.
## If @var{tol} is negative use it as a relative tolerance, will produce an
## error if
## @code{abs(@var{observed} - @var{expected}) > abs(@var{tol} *
## @var{expected})}.  If @var{expected} is zero @var{tol} will always be used as
## an absolute tolerance.
## @end table
## @seealso{test, fail}
## @end deftypefn

## FIXME: Output throttling: don't print out the entire 100x100 matrix,
## but instead give a summary; don't print out the whole list, just
## say what the first different element is, etc.  To do this, make
## the message generation type specific.

function assert (cond, varargin)

  in = deblank (argn(1,:));
  for i = 2:rows (argn)
    in = cstrcat (in, ",", deblank (argn(i,:)));
  endfor
  in = cstrcat ("(", in, ")");

  if (nargin == 1 || (nargin > 1 && islogical (cond) && ischar (varargin{1})))
    if ((! isnumeric (cond) && ! islogical (cond)) || ! all (cond(:)))
      if (nargin == 1)
        ## Say which elements failed?
        error ("assert %s failed", in);
      else
        error (varargin{:});
      endif
    endif
  else
    if (nargin < 2 || nargin > 3)
      print_usage ();
    endif

    expected = varargin {1};
    if (nargin < 3)
      tol = 0;
    else
      tol = varargin {2};
    endif

    if (exist ("argn") == 0)
      argn = " ";
    endif

    coda = "";
    iserror = 0;


    if (ischar (expected))
      iserror = (! ischar (cond) || ! strcmp (cond, expected));

    elseif (iscell (expected))
      if (! iscell (cond) || any (size (cond) != size (expected)))
        iserror = 1;
      else
        try
          for i = 1:length (expected(:))
            assert (cond{i}, expected{i}, tol);
          endfor
        catch
          iserror = 1;
        end_try_catch
      endif

    elseif (isstruct (expected))
      if (! isstruct (cond) || any (size (cond) != size (expected))
          || rows (fieldnames (cond)) != rows (fieldnames (expected)))
        iserror = 1;
      else
        try
          empty = numel (cond) == 0;
          normal = numel (cond) == 1;
          for [v, k] = cond
            if (! isfield (expected, k))
              error ();
            endif
            if (empty)
              v = cell (1, 0);
            endif
            if (normal)
              v = {v};
            else
              v = v(:)';
            endif
            assert (v, {expected.(k)}, tol);
          endfor
        catch
          iserror = 1;
        end_try_catch
      endif

    elseif (ndims (cond) != ndims (expected)
            || any (size (cond) != size (expected)))
      iserror = 1;
      coda = "Dimensions don't match";

    else
      if (nargin < 3)
        ## Without explicit tolerance, be more strict.
        if (! strcmp(class (cond), class (expected)))
          iserror = 1;
          coda = cstrcat ("Class ", class (cond), " != ", class (expected));
        elseif (isnumeric (cond))
          if (issparse (cond) != issparse (expected))
            if (issparse (cond))
              iserror = 1;
              coda = "sparse != non-sparse";
            else
              iserror = 1;
              coda = "non-sparse != sparse";
            endif
          elseif (iscomplex (cond) != iscomplex (expected))
            if (iscomplex (cond))
              iserror = 1;
              coda = "complex != real";
            else
              iserror = 1;
              coda = "real != complex";
            endif
          endif
        endif
      endif

      if (! iserror)
        ## Numeric.
        A = cond(:);
        B = expected(:);
        ## Check exceptional values.
        if (any (isna (A) != isna (B)))
          iserror = 1;
          coda = "NAs don't match";
        elseif (any (isnan (A) != isnan (B)))
          iserror = 1;
          coda = "NaNs don't match";
          ## Try to avoid problems comparing strange values like Inf+NaNi.
        elseif (any (isinf (A) != isinf (B))
                || any (A(isinf (A) & ! isnan (A)) != B(isinf (B) & ! isnan (B))))
          iserror = 1;
          coda = "Infs don't match";
        else
          ## Check normal values.
          A = A(finite (A));
          B = B(finite (B));
          if (tol == 0)
            err = any (A != B);
            errtype = "values do not match";
          elseif (tol >= 0)
            err = max (abs (A - B));
            errtype = "maximum absolute error %g exceeds tolerance %g";
          else
            abserr = max (abs (A(B == 0)));
            A = A(B != 0);
            B = B(B != 0);
            relerr = max (abs (A - B) ./ abs (B));
            err = max ([abserr; relerr]);
            errtype = "maximum relative error %g exceeds tolerance %g";
          endif
          if (err > abs (tol))
            iserror = 1;
            coda = sprintf (errtype, err, abs (tol));
          endif
        endif
      endif

    endif

    if (! iserror)
      return;
    endif

    ## Pretty print the "expected but got" info, trimming leading and
    ## trailing "\n".
    str = disp (expected);
    idx = find (str != "\n");
    if (! isempty (idx))
      str = str(idx(1):idx(end));
    endif
    str2 = disp (cond);
    idx = find (str2 != "\n");
    if (! isempty (idx))
      str2 = str2 (idx(1):idx(end));
    endif
    msg = cstrcat ("assert ", in, " expected\n", str, "\nbut got\n", str2);
    if (! isempty (coda))
      msg = cstrcat (msg, "\n", coda);
    endif
    error ("%s", msg);
    ## disp (msg);
    ## error ("assertion failed");
  endif
endfunction

## empty
%!assert([])
%!assert(zeros(3,0),zeros(3,0))
%!error assert(zeros(3,0),zeros(0,2))
%!error assert(zeros(3,0),[])
%!fail("assert(zeros(2,0,2),zeros(2,0))", "Dimensions don't match")

## conditions
%!assert(isempty([]))
%!assert(1)
%!error assert(0)
%!assert(ones(3,1))
%!assert(ones(1,3))
%!assert(ones(3,4))
%!error assert([1,0,1])
%!error assert([1;1;0])
%!error assert([1,0;1,1])

## vectors
%!assert([1,2,3],[1,2,3]);
%!assert([1;2;3],[1;2;3]);
%!error assert([2;2;3],[1;2;3]);
%!error assert([1,2,3],[1;2;3]);
%!error assert([1,2],[1,2,3]);
%!error assert([1;2;3],[1;2]);
%!assert([1,2;3,4],[1,2;3,4]);
%!error assert([1,4;3,4],[1,2;3,4])
%!error assert([1,3;2,4;3,5],[1,2;3,4])

## exceptional values
%!assert([NaN, NA, Inf, -Inf, 1+eps, eps],[NaN, NA, Inf, -Inf, 1, 0],eps)
%!error assert(NaN, 1)
%!error assert(NA, 1)
%!error assert(-Inf, Inf)

## scalars
%!error assert(3, [3,3; 3,3])
%!error assert([3,3; 3,3], 3)
%!assert(3, 3);
%!assert(3+eps, 3, eps);
%!assert(3, 3+eps, eps);
%!error assert(3+2*eps, 3, eps);
%!error assert(3, 3+2*eps, eps);

## must give a little space for floating point errors on relative
%!assert(100+100*eps, 100, -2*eps);
%!assert(100, 100+100*eps, -2*eps);
%!error assert(100+300*eps, 100, -2*eps);
%!error assert(100, 100+300*eps, -2*eps);
%!error assert(3, [3,3]);
%!error assert(3,4);

## test relative vs. absolute tolerances
%!test  assert (0.1+eps, 0.1,  2*eps);  # accept absolute
%!error assert (0.1+eps, 0.1, -2*eps);  # fail relative
%!test  assert (100+100*eps, 100, -2*eps);  # accept relative
%!error assert (100+100*eps, 100,  2*eps);  # fail absolute

## structures
%!shared x,y
%! x.a = 1; x.b=[2, 2];
%! y.a = 1; y.b=[2, 2];
%!assert (x,y)
%!test y.b=3;
%!error assert (x,y)
%!error assert (3, x);
%!error assert (x, 3);

## check usage statements
%!error assert
%!error assert(1,2,3,4,5)

## strings
%!assert("dog","dog")
%!error assert("dog","cat")
%!error assert("dog",3);
%!error assert(3,"dog");
