IRandomNumberGenerator.h

// -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
//-----------------------------------------------------------------------------
// Copyright 2000-2026 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
// See the top-level COPYRIGHT file for details.
// SPDX-License-Identifier: Apache-2.0
//-----------------------------------------------------------------------------
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/* IRandomNumberGenerator.h                                    (C) 2000-2026 */
/*                                                                           */
/* Interface for random number generator.                                    */
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#ifndef ARCANE_CORE_IRANDOMNUMBERGENERATOR_H
#define ARCANE_CORE_IRANDOMNUMBERGENERATOR_H
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#include "arcane/utils/Array.h"
#include "arcane/utils/UtilsTypes.h"
 
#include <cstring>
 
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namespace Arcane
{
 
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class ARCANE_CORE_EXPORT RNGSeedHelper
{
 public:

  RNGSeedHelper(ByteArrayView av)
  {
    m_seed = av;
  }

  template <class T>
  RNGSeedHelper(T* var)
  {
    m_seed = ByteArrayView(sizeof(T), (Byte*)var);
  }
 
  virtual ~RNGSeedHelper() = default;
 
 public:

  template <class T>
  bool setValue(T value_in)
  {
    if (m_seed.empty()) {
      return false;
    }
    memcpy(m_seed.data(), &value_in, std::min(m_seed.size(), (Integer)sizeof(T)));
    for (Integer i = sizeof(T); i < m_seed.size(); i++) {
      m_seed[i] = 0x00;
    }
    return true;
  }

  template <class T>
  bool value(T& value_out, bool without_size_check = true) const
  {
    if (m_seed.empty() || (!without_size_check && sizeof(T) != m_seed.size())) {
      return false;
    }
    value_out = 0;
    std::memcpy(&value_out, m_seed.data(), std::min(m_seed.size(), (Integer)sizeof(T)));
    return true;
  }

  template <class T>
  bool value(T* value_out, bool without_size_check = true) const
  {
    if (m_seed.empty() || (sizeof(T) != m_seed.size() && !without_size_check)) {
      return false;
    }
    *value_out = 0;
    memcpy(value_out, m_seed.data(), std::min(m_seed.size(), (Integer)sizeof(T)));
    return true;
  }

  Integer sizeOfSeed() const
  {
    return m_seed.size();
  }

  ByteConstArrayView constView() const
  {
    return m_seed.constView();
  }

  ByteArrayView view()
  {
    return m_seed;
  }

  template <class T>
  RNGSeedHelper& operator=(T new_value)
  {
    setValue(new_value);
    return *this;
  }

  ByteUniqueArray copy()
  {
    return ByteUniqueArray(m_seed);
  }
 
 protected:
 
  ByteArrayView m_seed;
};

class ARCANE_CORE_EXPORT IRandomNumberGenerator
{
 public:
 
  virtual ~IRandomNumberGenerator() = default;
 
 public:

  virtual bool initSeed() = 0;

  virtual bool initSeed(ByteArrayView seed) = 0;

  virtual ByteConstArrayView viewSeed() = 0;

  virtual ByteUniqueArray emptySeed() = 0;

  virtual Integer neededSizeOfSeed() = 0;

  virtual bool isLeapSeedSupported() = 0;

  virtual ByteUniqueArray generateRandomSeed(Integer leap = 0) = 0;

  virtual ByteUniqueArray generateRandomSeed(ByteArrayView parent_seed, Integer leap = 0) = 0;

  virtual bool isLeapNumberSupported() = 0;

  virtual Real generateRandomNumber(Integer leap = 0) = 0;

  virtual Real generateRandomNumber(ByteArrayView seed, Integer leap = 0) = 0;
};
 
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} // End namespace Arcane
 
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#endif