/*

Copyright (C) 2008-2016 Jaroslav Hajek

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/>.

*/

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include "error.h"
#include "ovl.h"
#include "ov.h"
#include "pt-cbinop.h"
#include "pt-bp.h"
#include "pt-unop.h"
#include "pt-walk.h"

namespace octave
{
  typedef tree_expression* tree_expression_ptr_t;

  octave_value_list
  tree_compound_binary_expression::rvalue (int nargout)
  {
    octave_value_list retval;

    if (nargout > 1)
      error ("binary operator '%s': invalid number of output arguments",
             oper ().c_str ());

    retval = rvalue1 (nargout);

    return retval;
  }

  octave_value
  tree_compound_binary_expression::rvalue1 (int)
  {
    octave_value retval;

    if (op_lhs)
      {
        octave_value a = op_lhs->rvalue1 ();

        if (a.is_defined () && op_rhs)
          {
            octave_value b = op_rhs->rvalue1 ();

            if (b.is_defined ())
              retval = ::do_binary_op (etype, a, b);
          }
      }

    return retval;
  }
}

// If a tree expression is a transpose or hermitian transpose, return
// the argument and corresponding operator.

static octave_value::unary_op
strip_trans_herm (octave::tree_expression_ptr_t& exp)
{
  if (exp->is_unary_expression ())
    {
      octave::tree_unary_expression *uexp =
        dynamic_cast<octave::tree_unary_expression *> (exp);

      octave_value::unary_op op = uexp->op_type ();

      if (op == octave_value::op_transpose
          || op == octave_value::op_hermitian)
        exp = uexp->operand ();
      else
        op = octave_value::unknown_unary_op;

      return op;
    }
  else
    return octave_value::unknown_unary_op;
}

static octave_value::unary_op
strip_not (octave::tree_expression_ptr_t& exp)
{
  if (exp->is_unary_expression ())
    {
      octave::tree_unary_expression *uexp =
        dynamic_cast<octave::tree_unary_expression *> (exp);

      octave_value::unary_op op = uexp->op_type ();

      if (op == octave_value::op_not)
        exp = uexp->operand ();
      else
        op = octave_value::unknown_unary_op;

      return op;
    }
  else
    return octave_value::unknown_unary_op;
}

// Possibly convert multiplication to trans_mul, mul_trans, herm_mul,
// or mul_herm.

static octave_value::compound_binary_op
simplify_mul_op (octave::tree_expression_ptr_t& a,
                 octave::tree_expression_ptr_t& b)
{
  octave_value::compound_binary_op retop
    = octave_value::unknown_compound_binary_op;

  octave_value::unary_op opa = strip_trans_herm (a);

  if (opa == octave_value::op_hermitian)
    retop = octave_value::op_herm_mul;
  else if (opa == octave_value::op_transpose)
    retop = octave_value::op_trans_mul;
  else
    {
      octave_value::unary_op opb = strip_trans_herm (b);

      if (opb == octave_value::op_hermitian)
        retop = octave_value::op_mul_herm;
      else if (opb == octave_value::op_transpose)
        retop = octave_value::op_mul_trans;
    }

  return retop;
}

// Possibly convert left division to trans_ldiv or herm_ldiv.

static octave_value::compound_binary_op
simplify_ldiv_op (octave::tree_expression_ptr_t& a,
                  octave::tree_expression_ptr_t&)
{
  octave_value::compound_binary_op retop
    = octave_value::unknown_compound_binary_op;

  octave_value::unary_op opa = strip_trans_herm (a);

  if (opa == octave_value::op_hermitian)
    retop = octave_value::op_herm_ldiv;
  else if (opa == octave_value::op_transpose)
    retop = octave_value::op_trans_ldiv;

  return retop;
}

// Possibly contract and/or with negation.

static octave_value::compound_binary_op
simplify_and_or_op (octave::tree_expression_ptr_t& a,
                    octave::tree_expression_ptr_t& b,
                    octave_value::binary_op op)
{
  octave_value::compound_binary_op retop
    = octave_value::unknown_compound_binary_op;

  octave_value::unary_op opa = strip_not (a);

  if (opa == octave_value::op_not)
    {
      if (op == octave_value::op_el_and)
        retop = octave_value::op_el_not_and;
      else if (op == octave_value::op_el_or)
        retop = octave_value::op_el_not_or;
    }
  else
    {
      octave_value::unary_op opb = strip_not (b);

      if (opb == octave_value::op_not)
        {
          if (op == octave_value::op_el_and)
            retop = octave_value::op_el_and_not;
          else if (op == octave_value::op_el_or)
            retop = octave_value::op_el_or_not;
        }
    }

  return retop;
}

namespace octave
{
  tree_binary_expression *
  maybe_compound_binary_expression (tree_expression *a, tree_expression *b,
                                    int l, int c, octave_value::binary_op t)
  {
    tree_expression *ca = a;
    tree_expression *cb = b;
    octave_value::compound_binary_op ct;

    switch (t)
      {
      case octave_value::op_mul:
        ct = simplify_mul_op (ca, cb);
        break;

      case octave_value::op_ldiv:
        ct = simplify_ldiv_op (ca, cb);
        break;

      case octave_value::op_el_and:
      case octave_value::op_el_or:
        ct = simplify_and_or_op (ca, cb, t);
        break;

      default:
        ct = octave_value::unknown_compound_binary_op;
        break;
      }

    tree_binary_expression *ret = (ct == octave_value::unknown_compound_binary_op)
      ? new tree_binary_expression (a, b, l, c, t)
      : new tree_compound_binary_expression (a, b, l,
                                             c, t, ca,
                                             cb, ct);

    return ret;
  }
}