////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1996-2021 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 (octave_ov_base_h)
#define octave_ov_base_h 1

#include "octave-config.h"

#include <cstdlib>

#include <iosfwd>
#include <list>
#include <memory>
#include <string>

#include "Range.h"
#include "data-conv.h"
#include "mx-base.h"
#include "str-vec.h"

#include "oct-hdf5-types.h"
#include "oct-stream.h"

namespace octave
{
  class stack_frame;
  class type_info;

  // FIXME: This is not ideal, but it avoids including
  // interpreter-private.h here and bringing in a lot of unnecessary
  // symbols that require even more header files.

  extern OCTINTERP_API type_info& __get_type_info__ (const std::string&);
}

class Cell;
class float_display_format;
class mxArray;
class octave_map;
class octave_scalar_map;
class octave_value;
class octave_value_list;
class octave_classdef;
class octave_function;
class octave_user_function;
class octave_user_script;
class octave_user_code;
class octave_fcn_handle;
class octave_value_list;

enum builtin_type_t
{
  btyp_double,
  btyp_float,
  btyp_complex,
  btyp_float_complex,
  btyp_int8,
  btyp_int16,
  btyp_int32,
  btyp_int64,
  btyp_uint8,
  btyp_uint16,
  btyp_uint32,
  btyp_uint64,
  btyp_bool,
  btyp_char,
  btyp_struct,
  btyp_cell,
  btyp_func_handle,
  btyp_unknown,
  btyp_num_types = btyp_unknown
};

extern OCTINTERP_API std::string btyp_class_name [];

inline bool btyp_isnumeric (builtin_type_t btyp)
{ return btyp <= btyp_uint64; }

inline bool btyp_isinteger (builtin_type_t btyp)
{ return btyp >= btyp_int8 && btyp <= btyp_uint64; }

inline bool btyp_isfloat (builtin_type_t btyp)
{ return btyp <= btyp_float_complex; }

inline bool btyp_isarray (builtin_type_t btyp)
{ return btyp <= btyp_char; }

//! Determine the resulting type for a possible mixed-type operation.
//!
//! Rules for the resulting type:
//!   - bool -> double
//!   - single + double -> single
//!   - real + complex -> complex
//!   - integer + real -> integer
//!   - uint + uint -> uint (the bigger one)
//!   - sint + sint -> sint (the bigger one)
//!
//! @return The resulting type or "unknown type", if the resulting type cannot
//!         be determined.

extern OCTINTERP_API
builtin_type_t btyp_mixed_numeric (builtin_type_t x, builtin_type_t y);

template <typename T>
struct class_to_btyp
{
  static const builtin_type_t btyp = btyp_unknown;
};

template <builtin_type_t BTYP>
struct btyp_to_class
{
  typedef void type;
};

#define DEF_BTYP_TRAITS(BTYP, CLASS)            \
  template <>                                   \
  struct class_to_btyp<CLASS>                   \
  {                                             \
    static const builtin_type_t btyp = BTYP;    \
  };                                            \
                                                \
  template <>                                   \
  struct btyp_to_class<BTYP>                    \
  {                                             \
    typedef CLASS type;                         \
  }

DEF_BTYP_TRAITS (btyp_double, double);
DEF_BTYP_TRAITS (btyp_float, float);
DEF_BTYP_TRAITS (btyp_complex, Complex);
DEF_BTYP_TRAITS (btyp_float_complex, FloatComplex);
DEF_BTYP_TRAITS (btyp_int8, octave_int8);
DEF_BTYP_TRAITS (btyp_int16, octave_int16);
DEF_BTYP_TRAITS (btyp_int32, octave_int32);
DEF_BTYP_TRAITS (btyp_int64, octave_int64);
DEF_BTYP_TRAITS (btyp_uint8, octave_uint8);
DEF_BTYP_TRAITS (btyp_uint16, octave_uint16);
DEF_BTYP_TRAITS (btyp_uint32, octave_uint32);
DEF_BTYP_TRAITS (btyp_uint64, octave_uint64);
DEF_BTYP_TRAITS (btyp_bool, bool);
DEF_BTYP_TRAITS (btyp_char, char);


// T_ID is the type id of struct objects, set by register_type().
// T_NAME is the type name of struct objects.

#define OCTAVE_EMPTY_CPP_ARG /* empty */

#define DECLARE_OV_TYPEID_FUNCTIONS_AND_DATA                    \
  DECLARE_OV_TYPEID_FUNCTIONS_AND_DATA2 (OCTAVE_EMPTY_CPP_ARG)

#define DECLARE_OV_BASE_TYPEID_FUNCTIONS_AND_DATA       \
  DECLARE_OV_TYPEID_FUNCTIONS_AND_DATA2(virtual)

#define DECLARE_OV_TYPEID_FUNCTIONS_AND_DATA2(VIRTUAL)                  \
  public:                                                               \
    VIRTUAL int type_id (void) const { return t_id; }                   \
    VIRTUAL std::string type_name (void) const { return t_name; }       \
    VIRTUAL std::string class_name (void) const { return c_name; }      \
    static int static_type_id (void) { return t_id; }                   \
    static std::string static_type_name (void) { return t_name; }       \
    static std::string static_class_name (void) { return c_name; }      \
    static void register_type (void);                                   \
    static void register_type (octave::type_info&);                     \
                                                                        \
  private:                                                              \
    static int t_id;                                                    \
    static const std::string t_name;                                    \
    static const std::string c_name;

#define DECLARE_TEMPLATE_OV_TYPEID_SPECIALIZATIONS(cls, type)           \
  template <> void cls<type>::register_type (void);                     \
  template <> void cls<type>::register_type (octave::type_info&);       \
  template <> int cls<type>::t_id;                                      \
  template <> const std::string cls<type>::t_name;                      \
  template <> const std::string cls<type>::c_name;

#define DEFINE_OV_TYPEID_FUNCTIONS_AND_DATA_INTERNAL(tspec, t, n, c)    \
  tspec int t::t_id (-1);                                               \
  tspec const std::string t::t_name (n);                                \
  tspec const std::string t::c_name (c);                                \
  tspec void t::register_type (void)                                    \
  {                                                                     \
    octave::type_info& type_info                                        \
      = octave::__get_type_info__ (#t "::register_type");               \
                                                                        \
    register_type (type_info);                                          \
  }                                                                     \
  tspec void t::register_type (octave::type_info& ti)                   \
  {                                                                     \
    octave_value v (new t ());                                          \
    t_id = ti.register_type (t::t_name, t::c_name, v);                  \
  }

#define DEFINE_TEMPLATE_OV_TYPEID_FUNCTIONS_AND_DATA(t, n, c)           \
  DEFINE_OV_TYPEID_FUNCTIONS_AND_DATA_INTERNAL (template <>, t, n, c)

#define DEFINE_OV_TYPEID_FUNCTIONS_AND_DATA(t, n, c)            \
  DEFINE_OV_TYPEID_FUNCTIONS_AND_DATA_INTERNAL ( , t, n, c)

// A base value type, so that derived types only have to redefine what
// they need (if they are derived from octave_base_value instead of
// octave_value).

class
OCTINTERP_API
octave_base_value
{
public:

  typedef octave_base_value * (*type_conv_fcn) (const octave_base_value&);

  // type conversion, including result type information
  class type_conv_info
  {
  public:
    type_conv_info (type_conv_fcn f = nullptr, int t = -1)
      : _fcn (f), _type_id (t) { }

    operator type_conv_fcn (void) const { return _fcn; }

    octave_base_value * operator () (const octave_base_value& v) const
    { return (*_fcn) (v); }

    int type_id (void) const { return _type_id; }

  private:
    type_conv_fcn _fcn;
    int _type_id;
  };

  friend class octave_value;

  octave_base_value (void) : count (1) { }

  octave_base_value (const octave_base_value&) : count (1) { }

  virtual ~octave_base_value (void) = default;

  // Unconditional clone.  Always clones.
  virtual octave_base_value *
  clone (void) const { return new octave_base_value (*this); }

  // Empty clone.
  virtual octave_base_value *
  empty_clone (void) const;

  // Unique clone.  Usually clones, but may be overridden to fake the
  // cloning when sharing copies is to be controlled from within an
  // instance (see octave_class).
  virtual octave_base_value *
  unique_clone (void) { return clone (); }

  virtual void break_closure_cycles (const std::shared_ptr<octave::stack_frame>&) { }

  virtual type_conv_info
  numeric_conversion_function (void) const
  { return type_conv_info (); }

  virtual type_conv_info
  numeric_demotion_function (void) const
  { return type_conv_info (); }

  virtual octave_value squeeze (void) const;

  virtual octave_value full_value (void) const;

  virtual octave_value as_double (void) const;
  virtual octave_value as_single (void) const;

  virtual octave_value as_int8 (void) const;
  virtual octave_value as_int16 (void) const;
  virtual octave_value as_int32 (void) const;
  virtual octave_value as_int64 (void) const;

  virtual octave_value as_uint8 (void) const;
  virtual octave_value as_uint16 (void) const;
  virtual octave_value as_uint32 (void) const;
  virtual octave_value as_uint64 (void) const;

  virtual octave_base_value * try_narrowing_conversion (void) { return nullptr; }

  virtual void maybe_economize (void) { }

  virtual Matrix size (void);

  virtual octave_idx_type xnumel (const octave_value_list&);

  // FIXME: Do we really need all three of these versions of subsref?

  virtual octave_value
  subsref (const std::string& type,
           const std::list<octave_value_list>& idx);

  virtual octave_value_list
  subsref (const std::string& type,
           const std::list<octave_value_list>& idx,
           int nargout);

  virtual octave_value
  subsref (const std::string& type,
           const std::list<octave_value_list>& idx,
           bool auto_add);

  virtual octave_value
  do_index_op (const octave_value_list& idx, bool resize_ok = false);

  virtual void assign (const std::string&, const octave_value&) { }

  virtual octave_value
  subsasgn (const std::string& type,
            const std::list<octave_value_list>& idx,
            const octave_value& rhs);

  virtual octave_value
  undef_subsasgn (const std::string& type,
                  const std::list<octave_value_list>& idx,
                  const octave_value& rhs);

  virtual octave::idx_vector index_vector (bool require_integers = false) const;

  virtual dim_vector dims (void) const { return dim_vector (); }

  octave_idx_type rows (void) const
  {
    const dim_vector dv = dims ();

    return dv(0);
  }

  octave_idx_type columns (void) const
  {
    const dim_vector dv = dims ();

    return dv(1);
  }

  virtual int ndims (void) const
  { return dims ().ndims (); }

  virtual octave_idx_type numel (void) const { return dims ().numel (); }

  virtual std::size_t byte_size (void) const { return 0; }

  virtual octave_idx_type nnz (void) const;

  virtual octave_idx_type nzmax (void) const;

  virtual octave_idx_type nfields (void) const;

  virtual octave_value reshape (const dim_vector&) const;

  virtual octave_value permute (const Array<int>& vec, bool = false) const;

  virtual octave_value resize (const dim_vector&, bool fill = false) const;

  virtual MatrixType matrix_type (void) const;

  virtual MatrixType matrix_type (const MatrixType& typ) const;

  virtual bool is_defined (void) const { return false; }

  virtual bool is_storable (void) const { return true; }

  bool isempty (void) const { return (dims ().any_zero ()); }

  bool is_zero_by_zero (void) const { return dims().zero_by_zero (); }

  virtual bool iscell (void) const { return false; }

  virtual bool iscellstr (void) const { return false; }

  virtual bool is_real_scalar (void) const { return false; }

  virtual bool is_real_matrix (void) const { return false; }

  virtual bool is_complex_scalar (void) const { return false; }

  virtual bool is_complex_matrix (void) const { return false; }

  virtual bool is_bool_scalar (void) const { return false; }

  virtual bool is_bool_matrix (void) const { return false; }

  virtual bool is_char_matrix (void) const { return false; }

  virtual bool is_diag_matrix (void) const { return false; }

  virtual bool is_perm_matrix (void) const { return false; }

  virtual bool is_string (void) const { return false; }

  virtual bool is_sq_string (void) const { return false; }

  virtual bool is_range (void) const { return false; }

  virtual bool isstruct (void) const { return false; }

  virtual bool isobject (void) const { return false; }

  virtual bool is_classdef_meta (void) const { return false; }

  virtual bool is_classdef_superclass_ref (void) const { return false; }

  virtual bool is_classdef_object (void) const { return false; }

  virtual bool is_package (void) const { return false; }

  virtual bool isjava (void) const { return false; }

  virtual bool is_cs_list (void) const { return false; }

  virtual bool is_magic_colon (void) const { return false; }

  virtual bool is_all_va_args (void) const { return false; }

  virtual octave_value all (int = 0) const;

  virtual octave_value any (int = 0) const;

  virtual builtin_type_t builtin_type (void) const { return btyp_unknown; }

  virtual bool is_double_type (void) const { return false; }

  virtual bool is_single_type (void) const { return false; }

  virtual bool isfloat (void) const { return false; }

  virtual bool is_int8_type (void) const { return false; }

  virtual bool is_int16_type (void) const { return false; }

  virtual bool is_int32_type (void) const { return false; }

  virtual bool is_int64_type (void) const { return false; }

  virtual bool is_uint8_type (void) const { return false; }

  virtual bool is_uint16_type (void) const { return false; }

  virtual bool is_uint32_type (void) const { return false; }

  virtual bool is_uint64_type (void) const { return false; }

  virtual bool islogical (void) const { return false; }

  virtual bool isinteger (void) const { return false; }

  virtual bool isreal (void) const { return false; }

  virtual bool iscomplex (void) const { return false; }

  // Would be nice to get rid of the next four functions:

  virtual bool is_scalar_type (void) const { return false; }

  virtual bool is_matrix_type (void) const { return false; }

  virtual bool isnumeric (void) const { return false; }

  virtual bool issparse (void) const { return false; }

  virtual bool is_true (void) const { return false; }

  virtual bool is_magic_int (void) const { return false; }

  virtual bool isnull (void) const { return false; }

  virtual bool is_constant (void) const { return false; }

  virtual bool is_function_handle (void) const { return false; }

  virtual bool is_anonymous_function (void) const { return false; }

  virtual bool is_inline_function (void) const { return false; }

  virtual bool is_function (void) const { return false; }

  virtual bool is_user_script (void) const { return false; }

  virtual bool is_user_function (void) const { return false; }

  virtual bool is_user_code (void) const { return false; }

  virtual bool is_builtin_function (void) const { return false; }

  virtual bool is_dld_function (void) const { return false; }

  virtual bool is_mex_function (void) const { return false; }

  virtual void erase_subfunctions (void) { }

  virtual short int short_value (bool = false, bool = false) const;

  virtual unsigned short int ushort_value (bool = false, bool = false) const;

  virtual int int_value (bool = false, bool = false) const;

  virtual unsigned int uint_value (bool = false, bool = false) const;

  virtual int nint_value (bool = false) const;

  virtual long int long_value (bool = false, bool = false) const;

  virtual unsigned long int ulong_value (bool = false, bool = false) const;

  virtual int64_t int64_value (bool = false, bool = false) const;

  virtual uint64_t uint64_value (bool = false, bool = false) const;

  virtual double double_value (bool = false) const;

  virtual float float_value (bool = false) const;

  virtual double scalar_value (bool frc_str_conv = false) const
  { return double_value (frc_str_conv); }

  virtual float float_scalar_value (bool frc_str_conv = false) const
  { return float_value (frc_str_conv); }

  virtual Cell cell_value (void) const;

  virtual Matrix matrix_value (bool = false) const;

  virtual FloatMatrix float_matrix_value (bool = false) const;

  virtual NDArray array_value (bool = false) const;

  virtual FloatNDArray float_array_value (bool = false) const;

  virtual Complex complex_value (bool = false) const;

  virtual FloatComplex float_complex_value (bool = false) const;

  virtual ComplexMatrix complex_matrix_value (bool = false) const;

  virtual FloatComplexMatrix float_complex_matrix_value (bool = false) const;

  virtual ComplexNDArray complex_array_value (bool = false) const;

  virtual FloatComplexNDArray float_complex_array_value (bool = false) const;

  virtual bool bool_value (bool = false) const;

  virtual boolMatrix bool_matrix_value (bool = false) const;

  virtual boolNDArray bool_array_value (bool = false) const;

  virtual charMatrix char_matrix_value (bool force = false) const;

  virtual charNDArray char_array_value (bool = false) const;

  virtual SparseMatrix sparse_matrix_value (bool = false) const;

  virtual SparseComplexMatrix sparse_complex_matrix_value (bool = false) const;

  virtual SparseBoolMatrix sparse_bool_matrix_value (bool = false) const;

  virtual DiagMatrix diag_matrix_value (bool = false) const;

  virtual FloatDiagMatrix float_diag_matrix_value (bool = false) const;

  virtual ComplexDiagMatrix complex_diag_matrix_value (bool = false) const;

  virtual FloatComplexDiagMatrix
  float_complex_diag_matrix_value (bool = false) const;

  virtual PermMatrix perm_matrix_value (void) const;

  virtual octave_int8 int8_scalar_value (void) const;

  virtual octave_int16 int16_scalar_value (void) const;

  virtual octave_int32 int32_scalar_value (void) const;

  virtual octave_int64 int64_scalar_value (void) const;

  virtual octave_uint8 uint8_scalar_value (void) const;

  virtual octave_uint16 uint16_scalar_value (void) const;

  virtual octave_uint32 uint32_scalar_value (void) const;

  virtual octave_uint64 uint64_scalar_value (void) const;

  virtual int8NDArray int8_array_value (void) const;

  virtual int16NDArray int16_array_value (void) const;

  virtual int32NDArray int32_array_value (void) const;

  virtual int64NDArray int64_array_value (void) const;

  virtual uint8NDArray uint8_array_value (void) const;

  virtual uint16NDArray uint16_array_value (void) const;

  virtual uint32NDArray uint32_array_value (void) const;

  virtual uint64NDArray uint64_array_value (void) const;

  virtual string_vector string_vector_value (bool pad = false) const;

  virtual std::string string_value (bool force = false) const;

  virtual Array<std::string> cellstr_value (void) const;

  virtual octave::range<float> float_range_value (void) const;

  virtual octave::range<double> range_value (void) const;

  virtual octave::range<octave_int8> int8_range_value (void) const;

  virtual octave::range<octave_int16> int16_range_value (void) const;

  virtual octave::range<octave_int32> int32_range_value (void) const;

  virtual octave::range<octave_int64> int64_range_value (void) const;

  virtual octave::range<octave_uint8> uint8_range_value (void) const;

  virtual octave::range<octave_uint16> uint16_range_value (void) const;

  virtual octave::range<octave_uint32> uint32_range_value (void) const;

  virtual octave::range<octave_uint64> uint64_range_value (void) const;

  virtual octave_map map_value (void) const;

  virtual octave_scalar_map scalar_map_value (void) const;

  virtual string_vector map_keys (void) const;

  virtual std::size_t nparents (void) const;

  virtual std::list<std::string> parent_class_name_list (void) const;

  virtual string_vector parent_class_names (void) const;

  virtual octave_base_value * find_parent_class (const std::string&)
  { return nullptr; }

  virtual octave_base_value * unique_parent_class (const std::string&)
  { return nullptr; }

  virtual bool is_instance_of (const std::string&) const
  { return false; }

  virtual octave_classdef * classdef_object_value (bool silent = false);

  virtual octave_function * function_value (bool silent = false);

  virtual octave_user_function * user_function_value (bool silent = false);

  virtual octave_user_script * user_script_value (bool silent = false);

  virtual octave_user_code * user_code_value (bool silent = false);

  virtual octave_fcn_handle * fcn_handle_value (bool silent = false);

  virtual octave_value_list list_value (void) const;

  virtual octave_value convert_to_str (bool pad = false, bool force = false,
                                       char type = '\'') const;
  virtual octave_value
  convert_to_str_internal (bool pad, bool force, char type) const;

  virtual void convert_to_row_or_column_vector (void);

  // The following extractor functions don't perform any implicit type
  // conversions.

  virtual std::string xstring_value () const;

  virtual bool print_as_scalar (void) const { return false; }

  virtual void print (std::ostream& os, bool pr_as_read_syntax = false);

  virtual void
  print_raw (std::ostream& os, bool pr_as_read_syntax = false) const;

  virtual bool
  print_name_tag (std::ostream& os, const std::string& name) const;

  virtual void
  print_with_name (std::ostream& output_buf, const std::string& name,
                   bool print_padding = true);

  virtual void short_disp (std::ostream& os) const { os << "..."; }

  virtual float_display_format get_edit_display_format (void) const;

  virtual std::string edit_display (const float_display_format&,
                                    octave_idx_type, octave_idx_type) const
  { return "#VAL"; }

  virtual void print_info (std::ostream& os, const std::string& prefix) const;

  virtual bool save_ascii (std::ostream& os);

  virtual bool load_ascii (std::istream& is);

  virtual bool save_binary (std::ostream& os, bool save_as_floats);

  virtual bool load_binary (std::istream& is, bool swap,
                            octave::mach_info::float_format fmt);

  virtual bool
  save_hdf5 (octave_hdf5_id loc_id, const char *name, bool save_as_floats);

  virtual bool
  load_hdf5 (octave_hdf5_id loc_id, const char *name);

  virtual int
  write (octave::stream& os, int block_size,
         oct_data_conv::data_type output_type, int skip,
         octave::mach_info::float_format flt_fmt) const;

  virtual void * mex_get_data (void) const { return nullptr; }

  virtual octave_idx_type * mex_get_ir (void) const { return nullptr; }

  virtual octave_idx_type * mex_get_jc (void) const { return nullptr; }

  virtual mxArray * as_mxArray (bool interleaved) const;

  virtual octave_value diag (octave_idx_type k = 0) const;

  virtual octave_value diag (octave_idx_type m, octave_idx_type n) const;

  virtual octave_value sort (octave_idx_type dim = 0,
                             sortmode mode = ASCENDING) const;
  virtual octave_value sort (Array<octave_idx_type> &sidx,
                             octave_idx_type dim = 0,
                             sortmode mode = ASCENDING) const;

  virtual sortmode issorted (sortmode mode = UNSORTED) const;

  virtual Array<octave_idx_type>
  sort_rows_idx (sortmode mode = ASCENDING) const;

  virtual sortmode is_sorted_rows (sortmode mode = UNSORTED) const;

  virtual void lock (void);

  virtual void unlock (void);

  virtual bool islocked (void) const { return false; }

  virtual void call_object_destructor (void) { }

  virtual octave_value dump (void) const;

  // Standard mappers.  Register new ones here.
  enum unary_mapper_t
  {
    umap_abs,
    umap_acos,
    umap_acosh,
    umap_angle,
    umap_arg,
    umap_asin,
    umap_asinh,
    umap_atan,
    umap_atanh,
    umap_cbrt,
    umap_ceil,
    umap_conj,
    umap_cos,
    umap_cosh,
    umap_erf,
    umap_erfinv,
    umap_erfcinv,
    umap_erfc,
    umap_erfcx,
    umap_erfi,
    umap_dawson,
    umap_exp,
    umap_expm1,
    umap_isfinite,
    umap_fix,
    umap_floor,
    umap_gamma,
    umap_imag,
    umap_isinf,
    umap_isna,
    umap_isnan,
    umap_lgamma,
    umap_log,
    umap_log2,
    umap_log10,
    umap_log1p,
    umap_real,
    umap_round,
    umap_roundb,
    umap_signum,
    umap_sin,
    umap_sinh,
    umap_sqrt,
    umap_tan,
    umap_tanh,
    umap_xisalnum,
    umap_xisalpha,
    umap_xisascii,
    umap_xiscntrl,
    umap_xisdigit,
    umap_xisgraph,
    umap_xislower,
    umap_xisprint,
    umap_xispunct,
    umap_xisspace,
    umap_xisupper,
    umap_xisxdigit,
    umap_xsignbit,
    umap_xtolower,
    umap_xtoupper,
    umap_unknown,
    num_unary_mappers = umap_unknown
  };

  virtual octave_value map (unary_mapper_t) const;

  // These are fast indexing & assignment shortcuts for extracting
  // or inserting a single scalar from/to an array.

  // Extract the n-th element, aka val(n).  Result is undefined if val is not
  // an array type or n is out of range.  Never error.
  virtual octave_value
  fast_elem_extract (octave_idx_type n) const;

  // Assign the n-th element, aka val(n) = x.  Returns false if val is not an
  // array type, x is not a matching scalar type, or n is out of range.
  // Never error.
  virtual bool
  fast_elem_insert (octave_idx_type n, const octave_value& x);

  // This is a helper for the above, to be overridden in scalar types.  The
  // whole point is to handle the insertion efficiently with just *two* VM
  // calls, which is basically the theoretical minimum.
  virtual bool
  fast_elem_insert_self (void *where, builtin_type_t btyp) const;

protected:

  // This should only be called for derived types.

  OCTINTERP_API octave_value
  numeric_assign (const std::string& type,
                  const std::list<octave_value_list>& idx,
                  const octave_value& rhs);

  void reset_indent_level (void) const
  { curr_print_indent_level = 0; }

  void increment_indent_level (void) const
  { curr_print_indent_level += 2; }

  void decrement_indent_level (void) const
  { curr_print_indent_level -= 2; }

  int current_print_indent_level (void) const
  { return curr_print_indent_level; }

  OCTINTERP_API void indent (std::ostream& os) const;

  OCTINTERP_API void newline (std::ostream& os) const;

  OCTINTERP_API void reset (void) const;

  // A reference count.
  // NOTE: the declaration is octave_idx_type because with 64-bit indexing,
  // it is well possible to have more than MAX_INT copies of a single value
  // (think of an empty cell array with >2G elements).
  octave::refcount<octave_idx_type> count;

  OCTINTERP_API static const char * get_umap_name (unary_mapper_t);

  OCTINTERP_API void warn_load (const char *type) const;
  OCTINTERP_API void warn_save (const char *type) const;

private:

  OCTINTERP_API void wrong_type_arg_error (void) const;

  static int curr_print_indent_level;
  static bool beginning_of_line;

  DECLARE_OV_BASE_TYPEID_FUNCTIONS_AND_DATA
};

// TRUE means to perform automatic sparse to real mutation if there
// is memory to be saved
extern OCTINTERP_API bool Vsparse_auto_mutate;

// Utility function to convert C++ arguments used in subsref/subsasgn into an
// octave_value_list object that can be used to call a function/method in the
// interpreter.
extern OCTINTERP_API octave_value
make_idx_args (const std::string& type,
               const std::list<octave_value_list>& idx,
               const std::string& who);

// Tells whether some regular octave_value_base methods are being called from
// within the "builtin" function.
extern OCTINTERP_API bool called_from_builtin (void);

#endif