dim-vector.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2003-2025 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// or <https://octave.org/copyright/>.
//
// Copyirght (C) 2009, 2010 VZLU Prague
//
// 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/>.
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////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include <limits>
#include <new>
#include <sstream>
 
#include "Array.h"
#include "dim-vector.h"
 
// The maximum allowed value for a dimension extent.  This will normally be a
// tiny bit off the maximum value of octave_idx_type.
// Currently 1 is subtracted to allow safe conversion of any 2D Array into
// Sparse, but this offset may change in the future.
octave_idx_type
dim_vector::dim_max ()
{
  return std::numeric_limits<octave_idx_type>::max () - 1;
}
 
void
dim_vector::chop_all_singletons ()
{
  int j = 0;
  int nd = ndims ();
 
  for (int i = 0; i < nd; i++)
    {
      if (xelem(i) != 1)
        xelem(j++) = xelem(i);
    }
 
  if (j == 1)
    xelem(1) = 1;
 
  m_num_dims = (j > 2 ? j : 2);
}
 
std::string
dim_vector::str (char sep) const
{
  std::ostringstream buf;
 
  for (int i = 0; i < ndims (); i++)
    {
      buf << xelem (i);
 
      if (i < ndims () - 1)
        buf << sep;
    }
 
  std::string retval = buf.str ();
 
  return retval;
}
 
int
dim_vector::num_ones () const
{
  int retval = 0;
 
  for (int i = 0; i < ndims (); i++)
    if (xelem (i) == 1)
      retval++;
 
  return retval;
}
 
octave_idx_type
dim_vector::safe_numel () const
{
  octave_idx_type idx_max = dim_max ();
  octave_idx_type n = 1;
  int n_dims = ndims ();
 
  for (int i = 0; i < n_dims; i++)
    {
      n *= xelem(i);
      if (xelem(i) != 0)
        idx_max /= xelem(i);
      if (idx_max <= 0)
        throw std::bad_alloc ();
    }
 
  return n;
}
 
dim_vector
dim_vector::squeeze () const
{
  dim_vector new_dims = *this;
  new_dims.chop_all_singletons ();
 
  // preserve orientation if there is only one non-singleton dimension left
  if (new_dims.ndims () == 2 && xelem(0) == 1 && new_dims.elem(1) == 1)
    return new_dims.as_row ();
 
  return new_dims;
}
 
// This is the rule for cat().  cat (dim, A, B) works if one
// of the following holds, in this order:
//
// 1. size (A, k) == size (B, k) for all k != dim.
// In this case, size (C, dim) = size (A, dim) + size (B, dim) and
// other sizes remain intact.
//
// 2. A is 0x0, in which case B is the result
// 3. B is 0x0, in which case A is the result
 
bool
dim_vector::concat (const dim_vector& dvb, int dim)
{
  int orig_nd = ndims ();
  int ndb = dvb.ndims ();
  int new_nd = (dim < ndb ? ndb : dim + 1);
  if (new_nd > orig_nd)
    resize (new_nd, 1);
  else
    new_nd = orig_nd;
 
  bool match = true;
 
  for (int i = 0; i < ndb; i++)
    {
      if (i != dim && xelem(i) != dvb(i))
        {
          match = false;
          break;
        }
    }
 
  for (int i = ndb; i < new_nd; i++)
    {
      if (i != dim && xelem(i) != 1)
        {
          match = false;
          break;
        }
    }
 
  if (match)
    xelem(dim) += (dim < ndb ? dvb(dim) : 1);
  else
    {
      // Dimensions don't match.  The only allowed fix is to omit 0x0.
      if (ndb == 2 && dvb(0) == 0 && dvb(1) == 0)
        match = true;
      else if (orig_nd == 2 && xelem(0) == 0 && xelem(1) == 0)
        {
          *this = dvb;
          match = true;
        }
    }
 
  chop_trailing_singletons ();
 
  return match;
}
 
// Rules for horzcat/vertcat are yet looser.
// two arrays A, B can be concatenated
// horizontally (dim = 2) or vertically (dim = 1) if one of the
// following holds, in this order:
//
// 1. cat (dim, A, B) works
//
// 2. A, B are 2D and one of them is an empty vector, in which
// case the result is the other one except if both of them
// are empty vectors, in which case the result is 0x0.
 
bool
dim_vector::hvcat (const dim_vector& dvb, int dim)
{
  if (concat (dvb, dim))
    return true;
  else if (ndims () == 2 && dvb.ndims () == 2)
    {
      bool e2dv = xelem(0) + xelem(1) == 1;
      bool e2dvb = dvb(0) + dvb(1) == 1;
      if (e2dvb)
        {
          if (e2dv)
            *this = dim_vector ();
          return true;
        }
      else if (e2dv)
        {
          *this = dvb;
          return true;
        }
    }
 
  return false;
}
 
dim_vector
dim_vector::redim (int n) const
{
  int n_dims = ndims ();
 
  if (n_dims == n)
    return *this;
  else if (n_dims < n)
    {
      dim_vector retval = alloc (n);
 
      std::copy_n (m_dims, n_dims, retval.m_dims);
      std::fill_n (retval.m_dims + n_dims, n - n_dims, 1);
 
      return retval;
    }
  else
    {
      if (n < 1)
        n = 1;
 
      dim_vector retval = alloc (n);
 
      std::copy_n (m_dims, n-1, retval.m_dims);
 
      // Accumulate overflow dimensions into last remaining dimension
      int k = xelem(n-1);
      for (int i = n; i < n_dims; i++)
        k *= xelem(i);
 
      retval.xelem(n-1) = k;
 
      // All dim_vectors are at least 2-D.  Make Nx1 if necessary.
      if (n == 1)
        retval.xelem(1) = 1;
 
      return retval;
    }
}
 
Array<octave_idx_type>
dim_vector::as_array () const
{
  octave_idx_type nd = ndims ();
 
  Array<octave_idx_type> retval (dim_vector (1, nd));
 
  for (octave_idx_type i = 0; i < nd; i++)
    retval(i) = elem (i);
 
  return retval;
}