pt-idx.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1996-2023 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// 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
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include "Cell.h"
#include "error.h"
#include "interpreter-private.h"
#include "oct-map.h"
#include "ovl.h"
#include "oct-lvalue.h"
#include "ov.h"
#include "pt-arg-list.h"
#include "pt-eval.h"
#include "pt-id.h"
#include "pt-idx.h"
#include "utils.h"
#include "variables.h"
#include "errwarn.h"
 
OCTAVE_BEGIN_NAMESPACE(octave)
 
// Index expressions.
 
tree_index_expression::tree_index_expression (int l, int c)
  : tree_expression (l, c), m_expr (nullptr), m_args (0), m_type (),
    m_arg_nm (), m_dyn_field (), m_word_list_cmd (false) { }
 
tree_index_expression::tree_index_expression (tree_expression *e,
    tree_argument_list *lst,
    int l, int c, char t)
  : tree_expression (l, c), m_expr (e), m_args (0), m_type (),
    m_arg_nm (), m_dyn_field (), m_word_list_cmd (false)
{
  append (lst, t);
}
 
tree_index_expression::tree_index_expression (tree_expression *e,
    const std::string& n,
    int l, int c)
  : tree_expression (l, c), m_expr (e), m_args (0), m_type (),
    m_arg_nm (), m_dyn_field (), m_word_list_cmd (false)
{
  append (n);
}
 
tree_index_expression::tree_index_expression (tree_expression *e,
    tree_expression *df,
    int l, int c)
  : tree_expression (l, c), m_expr (e), m_args (0), m_type (),
    m_arg_nm (), m_dyn_field (), m_word_list_cmd (false)
{
  append (df);
}
 
tree_index_expression *
tree_index_expression::append (tree_argument_list *lst, char t)
{
  m_args.push_back (lst);
  m_type.append (1, t);
  m_arg_nm.push_back (lst ? lst->get_arg_names () : string_vector ());
  m_dyn_field.push_back (static_cast<tree_expression *> (nullptr));
 
  if (lst && lst->has_magic_tilde ())
    error ("invalid use of empty argument (~) in index expression");
 
  return this;
}
 
tree_index_expression *
tree_index_expression::append (const std::string& n)
{
  m_args.push_back (static_cast<tree_argument_list *> (nullptr));
  m_type += '.';
  m_arg_nm.push_back (n);
  m_dyn_field.push_back (static_cast<tree_expression *> (nullptr));
 
  return this;
}
 
tree_index_expression *
tree_index_expression::append (tree_expression *df)
{
  m_args.push_back (static_cast<tree_argument_list *> (nullptr));
  m_type += '.';
  m_arg_nm.push_back ("");
  m_dyn_field.push_back (df);
 
  return this;
}
 
tree_index_expression::~tree_index_expression (void)
{
  delete m_expr;
 
  while (! m_args.empty ())
    {
      auto p = m_args.begin ();
      delete *p;
      m_args.erase (p);
    }
 
  while (! m_dyn_field.empty ())
    {
      auto p = m_dyn_field.begin ();
      delete *p;
      m_dyn_field.erase (p);
    }
}
 
// This is useful for printing the name of the variable in an indexed
// assignment.
 
std::string
tree_index_expression::name (void) const
{
  return m_expr->name ();
}
 
std::string
tree_index_expression::get_struct_index
(tree_evaluator& tw,
 std::list<string_vector>::const_iterator p_arg_nm,
 std::list<tree_expression *>::const_iterator p_dyn_field) const
{
  std::string fn = (*p_arg_nm)(0);
 
  if (fn.empty ())
    {
      tree_expression *df = *p_dyn_field;
 
      if (df)
        {
          octave_value t = df->evaluate (tw);
 
          fn = t.xstring_value ("dynamic structure field names must be strings");
        }
      else
        panic_impossible ();
    }
 
  return fn;
}
 
octave_lvalue
tree_index_expression::lvalue (tree_evaluator& tw)
{
  std::list<octave_value_list> idx;
 
  int n = m_args.size ();
 
  auto p_args = m_args.begin ();
  auto p_arg_nm = m_arg_nm.begin ();
  auto p_dyn_field = m_dyn_field.begin ();
 
  octave_lvalue retval = m_expr->lvalue (tw);
 
  unwind_action
  act ([&tw] (const octave_value& val,
              const std::string& index_type,
              const std::list<octave_value_list>& index_list)
  {
    tw.set_indexed_object (val);
    tw.set_index_list (index_type, index_list);
  }, tw.indexed_object (), tw.index_type (), tw.index_list ());
 
  tw.set_indexed_object (retval.value ());
  tw.clear_index_list ();
 
  for (int i = 0; i < n; i++)
    {
      switch (m_type[i])
        {
        case '(':
          {
            octave_value_list tidx = tw.make_value_list (*p_args, *p_arg_nm);
 
            tw.append_index_list ('(', tidx);
            idx.push_back (tidx);
          }
          break;
 
        case '{':
          {
            octave_value_list tidx = tw.make_value_list (*p_args, *p_arg_nm);
 
            tw.append_index_list ('{', tidx);
            idx.push_back (tidx);
          }
          break;
 
        case '.':
          {
            octave_value tidx = get_struct_index (tw, p_arg_nm, p_dyn_field);
 
            tw.append_index_list ('.', tidx);
            idx.push_back (tidx);
          }
          break;
 
        default:
          panic_impossible ();
        }
 
      if (idx.back ().empty ())
        error ("invalid empty index list");
 
      p_args++;
      p_arg_nm++;
      p_dyn_field++;
    }
 
  retval.set_index (m_type, idx);
 
  return retval;
}
 
tree_index_expression *
tree_index_expression::dup (symbol_scope& scope) const
{
  tree_index_expression *new_idx_expr
    = new tree_index_expression (line (), column ());
 
  new_idx_expr->m_expr = (m_expr ? m_expr->dup (scope) : nullptr);
 
  std::list<tree_argument_list *> new_args;
 
  for (const tree_argument_list *elt : m_args)
    new_args.push_back (elt ? elt->dup (scope) : nullptr);
 
  new_idx_expr->m_args = new_args;
 
  new_idx_expr->m_type = m_type;
 
  new_idx_expr->m_arg_nm = m_arg_nm;
 
  std::list<tree_expression *> new_dyn_field;
 
  for (const tree_expression *elt : m_dyn_field)
    new_dyn_field.push_back (elt ? elt->dup (scope) : nullptr);
 
  new_idx_expr->m_dyn_field = new_dyn_field;
 
  new_idx_expr->copy_base (*this);
 
  return new_idx_expr;
}
 
// Unlike Matlab, which does not allow the result of a function call
// or array indexing expression to be further indexed, Octave attempts
// to handle arbitrary index expressions.  For example, Octave allows
// expressions like
//
//   svd (rand (10))(1:5)
//
// Although octave_value objects may contain function objects, no
// indexing operation or function call is supposed to return them
// directly.  Instead, the language is supposed to only allow function
// objects to be stored as function handles (named or anonymous) or as
// inline functions.  The only place a function object should appear
// directly is if the symbol stored in a tree_identifier object
// resolves to a function.  This means that the only place we need to
// look for functions is in the first element of the index
// expression.
//
// Steps:
//
//  * Obtain the initial value from the expression component of the
//    tree_index_expression object.  If it is a tree_identifier object
//    indexed by '(args)' and the identifier is not a variable, then
//    perform a function call.  Use the (optional) arguments to perform
//    the function lookup so we choose the correct function or class
//    method to call.  Otherwise, evaluate the first expression
//    without any additional arguments.
//
//  * Iterate over the remaining elements of the index expression and
//    call the octave_value::subsref method.  If indexing a class or
//    classdef object, build up a list of indices for a call to the
//    subsref method for the object.  Otherwise, use the result of
//    each temporary evaluation for the next index element.
//
//  * If not indexing a class or classdef object and any partial
//    expression evaluation produces a class or classdef object, then
//    build up a complete argument list from that point on for a final
//    subsref call for that object.
//
//    Multiple partial evaluations may be required.  For example,
//    given a class or classdef object X, then for the expression
//
//      x.a{end}(2:end).b
//
//    we must evaluate x.a to obtain the size for the first {end}
//    expression, then we must evaluate x.a{end} to obtain the size
//    for the second (2:end) expression.  Finally, the complete
//    expression may be evaluated.
//
//    If X is a cell array in the above expression, and none of the
//    intermediate evaluations produces a class or classdef object,
//    then the evaluation is performed as the following series of
//    steps
//
//      tmp = x.a
//      tmp = tmp{end}
//      tmp = tmp(2:end)
//      result = tmp.b
//
//    If any of the partial evaluations produces a class or classdef
//    object, then the subsref method for that object is called as
//    described above.  For example, suppose x.a produces a classdef
//    object.  Then the evaluation is performed as the following
//    series of steps
//
//      base_expr = tmp = x.a
//      tmp = base_expr{end}
//      base_expr{end}(2:end).b
//
//    In the last two steps, the partial value computed in the
//    previous step is used to determine the value of END.
 
octave_value_list
tree_index_expression::evaluate_n (tree_evaluator& tw, int nargout)
{
  octave_value_list retval;
 
  panic_if (m_args.empty ());
 
  auto p_args = m_args.begin ();
  auto p_arg_nm = m_arg_nm.begin ();
  auto p_dyn_field = m_dyn_field.begin ();
 
  int n = m_args.size ();
  int beg = 0;
 
  octave_value base_expr_val;
 
  if (m_expr->is_identifier () && m_type[beg] == '(')
    {
      tree_identifier *id = dynamic_cast<tree_identifier *> (m_expr);
 
      bool is_var = tw.is_variable (m_expr);
 
      std::string nm =  id->name ();
 
      if (is_var && is_word_list_cmd ())
        {
          bool maybe_binary_op = false;
          if ((*p_args) && (*p_args)->length () > 0)
            {
              // check if first character of first argument might be (the
              // start of) a binary operator
              std::string ops = "+-*/\\.^|&";
              string_vector arg_list = (*p_args)->get_arg_names ();
              if (! arg_list.isempty ()
                  && (ops.find (arg_list(0)[1]) != std::string::npos))
                maybe_binary_op = true;
            }
 
          std::string advice;
          if (maybe_binary_op)
            advice = "\nCheck whitespace around potential binary operator.";
 
          error ("variable \"%s\" used as function in command style expression%s",
                 nm.c_str (), advice.c_str ());
        }
 
      if (! is_var)
        {
          octave_value_list first_args;
 
          tree_argument_list *al = *p_args;
 
          if (al && al->length () > 0)
            {
              unwind_action act ([&tw] (const std::list<octave_lvalue> *lvl)
              {
                tw.set_lvalue_list (lvl);
              }, tw.lvalue_list ());
 
              tw.set_lvalue_list (nullptr);
 
              string_vector anm = *p_arg_nm;
 
              first_args = tw.convert_to_const_vector (al);
 
              first_args.stash_name_tags (anm);
            }
 
          interpreter& interp = tw.get_interpreter ();
 
          symbol_table& symtab = interp.get_symbol_table ();
 
          octave_value val = symtab.find_function (nm, first_args);
 
          octave_function *fcn = nullptr;
 
          if (val.is_function ())
            fcn = val.function_value (true);
 
          if (fcn)
            {
              try
                {
                  retval = fcn->call (tw, nargout, first_args);
                }
              catch (index_exception& ie)
                {
                  tw.final_index_error (ie, m_expr);
                }
 
              beg++;
              p_args++;
              p_arg_nm++;
              p_dyn_field++;
 
              if (n > beg)
                {
                  // More indices to follow.  Silently ignore
                  // extra output values.
 
                  if (retval.length () == 0)
                    error ("indexing undefined value");
                  else
                    base_expr_val = retval(0);
                }
              else
                {
                  // No more indices, so we are done.
 
                  // See note at end of function about deleting
                  // temporaries prior to pushing result.
 
                  base_expr_val = octave_value ();
                  first_args = octave_value_list ();
 
                  return retval;
                }
            }
        }
    }
 
  if (base_expr_val.is_undefined ())
    base_expr_val = m_expr->evaluate (tw);
 
  // If we are indexing an object or looking at something like
  //
  //   classname.static_function (args, ...);
  //
  // then we'll just build a complete index list for one big subsref
  // call.  If the expression we are indexing is a classname then
  // base_expr_val will be an octave_classdef_meta object.  If we have
  // files in a +packagename folder, they will also be an
  // octave_classdef_meta object, but we don't want to index them.
 
  std::list<octave_value_list> idx_list;
 
  {
    // Note: need new scope so that the following unwind action will
    // happen before we perform the final indexing for objects (for
    // example).
 
    unwind_action
    act ([&tw] (const octave_value& val,
                const std::string& index_type,
                const std::list<octave_value_list>& index_list)
    {
      tw.set_indexed_object (val);
      tw.set_index_list (index_type, index_list);
    },
    tw.indexed_object (),
    tw.index_type (), tw.index_list ());
 
    tw.set_indexed_object ();
    tw.clear_index_list ();
 
    bool indexing_object = (base_expr_val.isobject ()
                            || base_expr_val.isjava ()
                            || (base_expr_val.is_classdef_meta ()
                                && ! base_expr_val.is_package ()));
 
    octave_value partial_expr_val = base_expr_val;
 
    for (int i = beg; i < n; i++)
      {
        if (i > beg)
          {
            if (! indexing_object)
              {
                // Evaluate what we have so far.
 
                try
                  {
                    // Silently ignore extra output values.
 
                    octave_value_list tmp_list
                      = base_expr_val.subsref (m_type.substr (beg, i-beg),
                                               idx_list, nargout);
 
                    partial_expr_val
                      = tmp_list.length () ? tmp_list(0) : octave_value ();
 
                    base_expr_val = partial_expr_val;
 
                    if (partial_expr_val.is_cs_list ())
                      err_indexed_cs_list ();
 
                    retval = partial_expr_val;
 
                    beg = i;
                    idx_list.clear ();
                    tw.clear_index_list ();
 
                    if (partial_expr_val.isobject ()
                        || partial_expr_val.isjava ()
                        || (partial_expr_val.is_classdef_meta ()
                            && ! partial_expr_val.is_package ()))
                      {
                        // Found an object, so now we'll build up
                        // complete index list for one big subsref
                        // call from this point on.
 
                        // FIXME: is is also possible to have a
                        // static method call buried somewhere in
                        // the depths of a complex indexing
                        // expression so that we would also need to
                        // check for an octave_classdef_meta object
                        // here?
 
                        indexing_object = true;
                      }
                  }
                catch (index_exception& ie)
                  {
                    tw.final_index_error (ie, m_expr);
                  }
              }
          }
 
        tw.set_indexed_object (partial_expr_val);
 
        switch (m_type[i])
          {
          case '(':
            {
              octave_value_list tmp = tw.make_value_list (*p_args, *p_arg_nm);
              tw.append_index_list ('(', tmp);
              idx_list.push_back (tmp);
            }
            break;
 
          case '{':
            {
              octave_value_list tmp = tw.make_value_list (*p_args, *p_arg_nm);
              tw.append_index_list ('{', tmp);
              idx_list.push_back (tmp);
            }
            break;
 
          case '.':
            {
              octave_value tmp = get_struct_index (tw, p_arg_nm, p_dyn_field);
              tw.append_index_list ('.', tmp);
              idx_list.push_back (tmp);
            }
            break;
 
          default:
            panic_impossible ();
          }
 
        p_args++;
        p_arg_nm++;
        p_dyn_field++;
      }
  }
 
  // If ! idx_list.empty () that means we still have stuff to index
  // otherwise they would have been dealt with and idx_list would have
  // been emptied.
  if (! idx_list.empty ())
    {
      // This is for +package and other classdef_meta objects
      if (! base_expr_val.is_function ()
          || base_expr_val.is_classdef_meta ())
        {
          try
            {
              retval = base_expr_val.subsref (m_type.substr (beg, n-beg),
                                              idx_list, nargout);
              beg = n;
              idx_list.clear ();
            }
          catch (index_exception& ie)
            {
              tw.final_index_error (ie, m_expr);
            }
        }
      else
        {
          // FIXME: we want this to only be a superclass constructor
          // call Should we actually make a check for this or are all
          // other types of calls already dealt with?
 
          octave_function *fcn = base_expr_val.function_value ();
 
          if (fcn)
            {
              try
                {
                  // FIXME: is it possible for the IDX_LIST to have
                  // more than one element here?  Do we need to check?
 
                  octave_value_list final_args;
 
                  if (idx_list.size () != 1)
                    error ("unexpected extra index at end of expression");
 
                  if (m_type[beg] != '(')
                    error ("invalid index type '%c' for function call",
                           m_type[beg]);
 
                  final_args = idx_list.front ();
 
                  // FIXME: Do we ever need the names of the arguments
                  // passed to FCN here?
 
                  retval = fcn->call (tw, nargout, final_args);
                }
              catch (index_exception& ie)
                {
                  tw.final_index_error (ie, m_expr);
                }
            }
        }
    }
 
  // FIXME: when can the following happen?  In what case does indexing
  // result in a value that is a function?  Classdef method calls?
  // Something else?
 
  octave_value val = (retval.length () ? retval(0) : octave_value ());
 
  if (val.is_function ())
    {
      octave_function *fcn = val.function_value (true);
 
      if (fcn)
        {
          octave_value_list final_args;
 
          if (! idx_list.empty ())
            {
              if (n - beg != 1)
                error ("unexpected extra index at end of expression");
 
              if (m_type[beg] != '(')
                error ("invalid index type '%c' for function call",
                       m_type[beg]);
 
              final_args = idx_list.front ();
            }
 
          retval = fcn->call (tw, nargout, final_args);
        }
    }
 
  // Delete any temporary values prior to returning so that
  // destructors for any temporary classdef handle objects will be
  // called before we return.
 
  idx_list.clear ();
  base_expr_val = octave_value ();
  val = octave_value ();
 
  return retval;
}
 
OCTAVE_END_NAMESPACE(octave)
 
/*
%!test
%! clear x;
%! clear y;
%! y = 3;
%! x(y(end)) = 1;
%! assert (x, [0, 0, 1]);
%! clear x;
%! clear y;
%! y = {3};
%! x(y{end}) = 1;
%! assert (x, [0, 0, 1]);
 
%!test
%! x = {1, 2, 3};
%! [x{:}] = deal (4, 5, 6);
%! assert (x, {4, 5, 6});
 
%!test
%! [x.a, x.b.c] = deal (1, 2);
%! assert (x.a == 1 && x.b.c == 2);
 
%!test
%! [x.a, x(2).b] = deal (1, 2);
%! assert (x(1).a == 1 && isempty (x(2).a) && isempty (x(1).b) && x(2).b == 2);
 
%!test
%! x = struct (zeros (0, 1), {"a", "b"});
%! x(2).b = 1;
%! assert (x(2).b == 1);
 
%!test
%! x = struct (zeros (0, 1), {"a", "b"});
%! x(2).b = 1;
%! assert (x(2).b == 1);
*/