pt-assign.cc

Go to the documentation of this file.

/*

Copyright (C) 1996-2015 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/>.

*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <iostream>
#include <set>

#include "defun.h"
#include "error.h"
#include "gripes.h"
#include "input.h"
#include "oct-obj.h"
#include "oct-lvalue.h"
#include "pager.h"
#include "ov.h"
#include "pt-arg-list.h"
#include "pt-bp.h"
#include "pt-assign.h"
#include "pt-eval.h"
#include "pt-walk.h"
#include "utils.h"
#include "variables.h"

// Simple assignment expressions.

tree_simple_assignment::tree_simple_assignment
  (tree_expression *le, tree_expression *re,
   bool plhs, int l, int c, octave_value::assign_op t)
 : tree_expression (l, c), lhs (le), rhs (re), preserve (plhs), etype (t)
{ }

tree_simple_assignment::~tree_simple_assignment (void)
{
  if (! preserve)
    delete lhs;

  delete rhs;
}

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

  if (nargout > 1)
    error ("invalid number of output arguments for expression X = RHS");
  else
    retval = rvalue1 (nargout);

  return retval;
}

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

  if (error_state)
    return retval;

  if (rhs)
    {
      octave_value rhs_val = rhs->rvalue1 ();

      if (! error_state)
        {
          if (rhs_val.is_undefined ())
            {
              error ("value on right hand side of assignment is undefined");
              return retval;
            }
          else
            {
              if (rhs_val.is_cs_list ())
                {
                  const octave_value_list lst = rhs_val.list_value ();

                  if (! lst.empty ())
                    rhs_val = lst(0);
                  else
                    {
                      error ("invalid number of elements on RHS of assignment");
                      return retval;
                    }
                }

              octave_lvalue ult = lhs->lvalue ();

              if (ult.numel () != 1)
                gripe_nonbraced_cs_list_assignment ();

              if (! error_state)
                {
                  ult.assign (etype, rhs_val);

                  if (! error_state)
                    {
                      if (etype == octave_value::op_asn_eq)
                        retval = rhs_val;
                      else
                        retval = ult.value ();

                      if (print_result ()
                          && tree_evaluator::statement_printing_enabled ())
                        {
                          // We clear any index here so that we can
                          // get the new value of the referenced
                          // object below, instead of the indexed
                          // value (which should be the same as the
                          // right hand side value).

                          ult.clear_index ();

                          octave_value lhs_val = ult.value ();

                          if (! error_state)
                            lhs_val.print_with_name (octave_stdout,
                                                     lhs->name ());
                        }
                    }
                }
            }
        }
    }

  return retval;
}

std::string
tree_simple_assignment::oper (void) const
{
  return octave_value::assign_op_as_string (etype);
}

tree_expression *
tree_simple_assignment::dup (symbol_table::scope_id scope,
                             symbol_table::context_id context) const
{
  tree_simple_assignment *new_sa
    = new tree_simple_assignment (lhs ? lhs->dup (scope, context) : 0,
                                  rhs ? rhs->dup (scope, context) : 0,
                                  preserve, etype);

  new_sa->copy_base (*this);

  return new_sa;
}

void
tree_simple_assignment::accept (tree_walker& tw)
{
  tw.visit_simple_assignment (*this);
}

// Multi-valued assignment expressions.

tree_multi_assignment::tree_multi_assignment
  (tree_argument_list *lst, tree_expression *r,
   bool plhs, int l, int c)
  : tree_expression (l, c), lhs (lst), rhs (r), preserve (plhs)
{ }

tree_multi_assignment::~tree_multi_assignment (void)
{
  if (! preserve)
    delete lhs;

  delete rhs;
}

octave_value
tree_multi_assignment::rvalue1 (int nargout)
{
  octave_value retval;

  const octave_value_list tmp = rvalue (nargout);

  if (! tmp.empty ())
    retval = tmp(0);

  return retval;
}

// FIXME: this works, but it would look a little better if
// it were broken up into a couple of separate functions.

octave_value_list
tree_multi_assignment::rvalue (int)
{
  octave_value_list retval;

  if (error_state)
    return retval;

  if (rhs)
    {
      std::list<octave_lvalue> lvalue_list = lhs->lvalue_list ();

      if (error_state)
        return retval;

      octave_idx_type n_out = 0;

      for (std::list<octave_lvalue>::const_iterator p = lvalue_list.begin ();
           p != lvalue_list.end ();
           p++)
        n_out += p->numel ();

      // The following trick is used to keep rhs_val constant.
      const octave_value_list rhs_val1 = rhs->rvalue (n_out, &lvalue_list);
      const octave_value_list rhs_val = (rhs_val1.length () == 1
                                         && rhs_val1(0).is_cs_list ()
                                         ? rhs_val1(0).list_value ()
                                         : rhs_val1);

      if (error_state)
        return retval;

      octave_idx_type k = 0;

      octave_idx_type n = rhs_val.length ();

      // To avoid copying per elements and possible optimizations, we
      // postpone joining the final values.
      std::list<octave_value_list> retval_list;

      tree_argument_list::iterator q = lhs->begin ();

      for (std::list<octave_lvalue>::iterator p = lvalue_list.begin ();
           p != lvalue_list.end ();
           p++)
        {
          tree_expression *lhs_elt = *q++;

          octave_lvalue ult = *p;

          octave_idx_type nel = ult.numel ();

          if (nel != 1)
            {
              if (k + nel <= n)
                {
                  // This won't do a copy.
                  octave_value_list ovl  = rhs_val.slice (k, nel);

                  ult.assign (octave_value::op_asn_eq,
                              octave_value (ovl, true));

                  if (! error_state)
                    {
                      retval_list.push_back (ovl);

                      k += nel;
                    }
                }
              else
                error ("some elements undefined in return list");
            }
          else
            {
              if (k < n)
                {
                  ult.assign (octave_value::op_asn_eq, rhs_val(k));

                  if (ult.is_black_hole ())
                    {
                      k++;
                      continue;
                    }
                  else if (! error_state)
                    {
                      retval_list.push_back (rhs_val(k));

                      k++;
                    }
                }
              else
                {
                  // This can happen for a function like
                  //
                  //   function varargout = f ()
                  //     varargout{1} = nargout;
                  //   endfunction
                  //
                  // called with
                  //
                  //    [a, ~] = f ();
                  //
                  // Then the list of of RHS values will contain one
                  // element but we are iterating over the list of all
                  // RHS values.  We shouldn't complain that a value we
                  // don't need is missing from the list.

                  if (ult.is_black_hole ())
                    {
                      k++;
                      continue;
                    }
                  else
                    error ("element number %d undefined in return list", k+1);
                }
            }

          if (error_state)
            break;
          else if (print_result ()
                   && tree_evaluator::statement_printing_enabled ())
            {
              // We clear any index here so that we can get
              // the new value of the referenced object below,
              // instead of the indexed value (which should be
              // the same as the right hand side value).

              ult.clear_index ();

              octave_value lhs_val = ult.value ();

              if (! error_state)
                lhs_val.print_with_name (octave_stdout,
                                         lhs_elt->name ());
            }

          if (error_state)
            break;

        }

      // Concatenate return values.
      retval = retval_list;

    }

  return retval;
}

/*
%!function varargout = f ()
%!  varargout{1} = nargout;
%!endfunction
%!
%!test
%! [a, ~] = f ();
%! assert (a, 2);
%!test
%! [a, ~, ~, ~, ~] = f ();
%! assert (a, 5);
*/

std::string
tree_multi_assignment::oper (void) const
{
  return octave_value::assign_op_as_string (op_type ());
}

tree_expression *
tree_multi_assignment::dup (symbol_table::scope_id scope,
                            symbol_table::context_id context) const
{
  tree_multi_assignment *new_ma
    = new tree_multi_assignment (lhs ? lhs->dup (scope, context) : 0,
                                 rhs ? rhs->dup (scope, context) : 0,
                                 preserve);

  new_ma->copy_base (*this);

  return new_ma;
}

void
tree_multi_assignment::accept (tree_walker& tw)
{
  tw.visit_multi_assignment (*this);
}