pt-assign.cc

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/*

Copyright (C) 1996-2012 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-walk.h"
#include "utils.h"
#include "variables.h"

// Simple assignment expressions.

// FIXME -- the following variable and the function that uses it
// should be removed from some future version of Octave.

static const char *former_built_in_variables[] =
{
  "DEFAULT_EXEC_PATH",
  "DEFAULT_LOADPATH",
  "EDITOR",
  "EXEC_PATH",
  "FFTW_WISDOM_PROGRAM",
  "IMAGEPATH",
  "INFO_FILE",
  "INFO_PROGRAM",
  "LOADPATH",
  "MAKEINFO_PROGRAM",
  "PAGER",
  "PS1",
  "PS2",
  "PS4",
  "__kluge_procbuf_delay__",
  "automatic_replot",
  "beep_on_error",
  "completion_append_char",
  "crash_dumps_octave_core",
  "current_script_file_name",
  "debug_on_error",
  "debug_on_interrupt",
  "debug_on_warning",
  "debug_symtab_lookups",
  "default_save_options",
  "echo_executing_commands",
  "fixed_point_format",
  "gnuplot_binary",
  "gnuplot_command_axes",
  "gnuplot_command_end",
  "gnuplot_command_plot",
  "gnuplot_command_replot",
  "gnuplot_command_splot",
  "gnuplot_command_title",
  "gnuplot_command_using",
  "gnuplot_command_with",
  "gnuplot_has_frames",
  "history_file",
  "history_size",
  "ignore_function_time_stamp",
  "max_recursion_depth",
  "octave_core_file_format",
  "octave_core_file_limit",
  "octave_core_file_name",
  "output_max_field_width",
  "output_precision",
  "page_output_immediately",
  "page_screen_output",
  "print_answer_id_name",
  "print_empty_dimensions",
  "print_rhs_assign_val",
  "save_header_format_string",
  "save_precision",
  "saving_history",
  "sighup_dumps_octave_core",
  "sigterm_dumps_octave_core",
  "silent_functions",
  "split_long_rows",
  "string_fill_char",
  "struct_levels_to_print",
  "suppress_verbose_help_message",
  "variables_can_hide_functions",
  "warn_assign_as_truth_value",
  "warn_associativity_change",
  "warn_divide_by_zero",
  "warn_empty_list_elements",
  "warn_fortran_indexing",
  "warn_function_name_clash",
  "warn_future_time_stamp",
  "warn_imag_to_real",
  "warn_matlab_incompatible",
  "warn_missing_semicolon",
  "warn_neg_dim_as_zero",
  "warn_num_to_str",
  "warn_precedence_change",
  "warn_reload_forces_clear",
  "warn_resize_on_range_error",
  "warn_separator_insert",
  "warn_single_quote_string",
  "warn_str_to_num",
  "warn_undefined_return_values",
  "warn_variable_switch_label",
  "whos_line_format",
  0,
};

static void
maybe_warn_former_built_in_variable (const std::string& nm)
{
  static bool initialized = false;

  static std::set<std::string> vars;

  if (! initialized)
    {
      const char **p = former_built_in_variables;

      while (*p)
        vars.insert (*p++);

      initialized = true;
    }

  if (vars.find (nm) != vars.end ())
    {
      const char *nm_c_str = nm.c_str ();

      warning_with_id ("Octave:built-in-variable-assignment",
                       "\
In recent versions of Octave, %s is a function instead\n\
of a built-in variable.\n\n\
By assigning to %s, you have created a variable that hides\n\
the function %s. To remove the variable and restore the \n\
function, type \"clear %s\"\n",
                       nm_c_str, nm_c_str, nm_c_str, nm_c_str);
    }
}

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),
      first_execution (true) { }

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 (first_execution && lhs)
    maybe_warn_former_built_in_variable (lhs->name ());

  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 ())
                        {
                          // 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 ());
                        }
                    }
                }
            }
        }
    }

  first_execution = false;

  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),
      first_execution (true) { }

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 (first_execution)
    {
      for (tree_argument_list::iterator p = lhs->begin (); p != lhs->end (); p++)
        {
          tree_expression *lhs_expr = *p;

          if (lhs_expr)
            maybe_warn_former_built_in_variable (lhs_expr->name ());
        }
    }

  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 ())
            {
              // 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;

    }

  first_execution = false;

  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);
}