tpl_random_queue.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
 
# ifndef TPL_RANDOM_QUEUE_H
# define TPL_RANDOM_QUEUE_H
 
# include <gsl/gsl_rng.h>
# include <htlist.H>
# include <ah-dry.H>
# include <tpl_dynArray.H>
# include <utility>
 # include <ah-errors.H>
 
namespace Aleph {
 
    template <class T> 
class Random_Set
      : public LocateFunctions<Random_Set<T>, T>,
  public FunctionalMethods<Random_Set<T>, T>,
  public GenericKeys<Random_Set<T>, T>,
  public EqualToMethod<Random_Set<T>>,
  public StlAlephIterator<Random_Set<T>>
{
private:
 
  DynArray<T> array;
  gsl_rng * r = nullptr;
 
public:
 
  using Set_Type = Random_Set; 
 
  using Item_Type = T; 
 
  [[nodiscard]] gsl_rng * get_rng() const { return r; }
 
  void set_seed(unsigned long seed) const noexcept { gsl_rng_set(r, seed); }
 
  [[nodiscard]] size_t size() const { return array.size(); }
  
  Random_Set() : array(0), r(nullptr)
  {
    r = gsl_rng_alloc (gsl_rng_mt19937);
    ah_bad_alloc_if(r == nullptr);
 
    gsl_rng_set(r, time(nullptr) % gsl_rng_max(r));
  }
 
  void swap(Random_Set & s)
  {
    array.swap(s.array);
    std::swap(r, s.r);
  }
 
  Random_Set(const Random_Set & s) : Random_Set()
  {
    s.for_each([this] (auto item) { this->append(item); });
  }
 
  Random_Set(Random_Set && s)  noexcept { swap(s); }
 
  Random_Set & operator = (const Random_Set & s)
  {
    if (this == &s)
      return *this;
 
    array.cut(0);  // Clear the array first
    s.for_each([this] (auto item) { this->append(item); });
 
    return *this;
  }
 
  Random_Set & operator = (Random_Set && s) noexcept
  {
    swap(s);
    return *this;
  }
 
  Random_Set(const DynList<T> & l) : Random_Set()
  {
    l.for_each([this] (const T & item) { append(item); });
  }
 
  template <class It> Random_Set(It b, It e) : Random_Set()
  {
    for (It it = b; it != e; ++it)
      append(*it);
  }
  
  Random_Set(std::initializer_list<T> l) : Random_Set()
  {
    for (const auto & item : l)
      append(item);
  }
 
  ~Random_Set()
  {
    if (r != nullptr)
      gsl_rng_free(r);
  }
 
  void put(const T & item)
  {
    static_assert(std::is_copy_constructible_v<T>,
                  "Random_Set::put requires copyable T");
    array.append(item);
  }
 
  
  void put(T && item)
  {
    static_assert(std::is_move_constructible_v<T>,
                  "Random_Set::put requires moveable T");
    array.append(std::forward<T>(item));
  }
 
  T & append(const T & item)
  {
    put(item);
    const size_t last_index = array.size() - 1;
    const size_t pos = gsl_rng_uniform_int(r, array.size()); // al azar
    if (pos != last_index)
      std::swap(array(pos), array(last_index));
    return array(pos);
  }
 
  T & append(T && item)
  {
    put(std::forward<T>(item));
    const size_t last_index = array.size() - 1;
    const size_t pos = gsl_rng_uniform_int(r, array.size()); // al azar
    if (pos != last_index)
      std::swap(array(pos), array(last_index));
    return array(pos);
  }
 
  T get()
  {
    ah_underflow_error_if(array.size() == 0) << "Random set is empty";
 
    const size_t pos = gsl_rng_uniform_int(r, array.size()); // al azar
    T ret_val = array.access(pos);
    array.access(pos) = array.access(array.size() - 1);
    array.cut(array.size() - 1);
    return ret_val;
  }
 
  // pick() is like get() but without removing the item
  T pick() const
  {
    ah_underflow_error_if(array.size() == 0) << "Random set is empty";
 
    const size_t pos = gsl_rng_uniform_int(r, array.size()); // al azar
    T ret_val = array.access(pos);
    std::swap(array.access(pos), array.access(0));
    return ret_val;
  }
 
  bool is_empty() const { return array.size() == 0; }
 
  struct Iterator : public DynArray<T>
  {
    using Base = DynArray<T>;
    using Base::Base;
  };
 
  template <class Operation>
  bool traverse(Operation & operation) 
  {
    return array.traverse(operation);
  }
 
  template <class Operation>
  bool traverse(Operation & operation) const
  {
    return const_cast<Random_Set*>(this)->traverse(operation);
  }
 
  template <class Operation>
  bool traverse(Operation && operation = Operation()) const
  {
    return traverse(operation);
  }
 
  template <class Operation>
  bool traverse(Operation && operation = Operation())
  {
    return traverse(operation);
  }
};
 
 
  template <typename T, template <typename> class C>
auto shuffle(const C<T> & c)
{
  Random_Set<T*> q;
  c.for_each([&q] (const T & item) { q.put(&const_cast<T&>(item)); });
  
  C<T> ret;
  while (not q.is_empty())
    ret.append(*q.get());
 
  return ret;
}
 
 
  template <typename T, template <typename> class C>
C<T*> shuffle_ptr(const C<T> & c)
{
  Random_Set<T*> q;
  c.for_each([&q] (const T & item) { q.put(&const_cast<T&>(item)); });
  
  C<T*> ret;
  while (not q.is_empty())
    ret.append(q.get());
 
  return ret;
}
 
} // end namespace Aleph
 
# endif // TPL_RANDOM_QUEUE_H