cookie_guard.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
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
 
#ifndef COOKIE_GUARD_H
#define COOKIE_GUARD_H
 
#include <vector>
#include <utility>
#include <tpl_graph.H>
 
namespace Aleph {
 
template <class GT>
class Cookie_Guard
{
public:
  using Node = typename GT::Node;
  using Arc = typename GT::Arc;
 
  using Node_Deleter = std::function<void(Node*)>;
  
  using Arc_Deleter = std::function<void(Arc*)>;
 
private:
  GT & graph;
  bool clear_nodes;
  bool clear_arcs;
  Node_Deleter node_deleter;
  Arc_Deleter arc_deleter;
  bool active;
 
public:
  Cookie_Guard(const GT & g, bool _clear_nodes = true, bool _clear_arcs = true) noexcept
    : graph(const_cast<GT &>(g)), clear_nodes(_clear_nodes), clear_arcs(_clear_arcs),
      node_deleter(nullptr), arc_deleter(nullptr), active(true)
  {}
 
  Cookie_Guard(const GT & g, Node_Deleter nd, Arc_Deleter ad = nullptr) noexcept
    : graph(const_cast<GT &>(g)), clear_nodes(true), clear_arcs(ad != nullptr),
      node_deleter(std::move(nd)), arc_deleter(std::move(ad)), active(true)
  {}
 
  Cookie_Guard(const Cookie_Guard &) = delete;
  Cookie_Guard & operator=(const Cookie_Guard &) = delete;
 
  Cookie_Guard(Cookie_Guard && other) noexcept
    : graph(other.graph), clear_nodes(other.clear_nodes),
      clear_arcs(other.clear_arcs), node_deleter(std::move(other.node_deleter)),
      arc_deleter(std::move(other.arc_deleter)), active(other.active)
  {
    other.active = false;
  }
 
  Cookie_Guard & operator=(Cookie_Guard && other) noexcept
  {
    if (this != &other)
      {
        release();
        clear_nodes = other.clear_nodes;
        clear_arcs = other.clear_arcs;
        node_deleter = std::move(other.node_deleter);
        arc_deleter = std::move(other.arc_deleter);
        active = other.active;
        other.active = false;
      }
    return *this;
  }
 
  void release() noexcept
  {
    active = false;
  }
 
  void clear_now()
  {
    if (not active)
      return;
 
    if (clear_nodes)
      {
        for (auto it = graph.get_node_it(); it.has_curr(); it.next_ne())
          {
            Node * p = it.get_curr();
            if (node_deleter)
              node_deleter(p);
            NODE_COOKIE(p) = nullptr;
          }
      }
 
    if (clear_arcs)
      {
        for (auto it = graph.get_arc_it(); it.has_curr(); it.next_ne())
          {
            Arc * a = it.get_curr();
            if (arc_deleter)
              arc_deleter(a);
            ARC_COOKIE(a) = nullptr;
          }
      }
 
    active = false;
  }
 
  ~Cookie_Guard()
  {
    clear_now();
  }
};
 
 
template <class GT>
class Cookie_Saver
{
public:
  using Node = typename GT::Node;
  using Arc = typename GT::Arc;
 
  using Node_Cleanup = std::function<void(Node*)>;
  
  using Arc_Cleanup = std::function<void(Arc*)>;
 
private:
  GT & graph;
  std::vector<std::pair<Node*, void*>> saved_node_cookies;
  std::vector<std::pair<Arc*, void*>> saved_arc_cookies;
  bool save_nodes;
  bool save_arcs;
  Node_Cleanup node_cleanup;
  Arc_Cleanup arc_cleanup;
  bool active;
 
public:
  Cookie_Saver(const GT & g, bool _save_nodes = true, bool _save_arcs = true)
    : graph(const_cast<GT &>(g)), save_nodes(_save_nodes), save_arcs(_save_arcs),
      node_cleanup(nullptr), arc_cleanup(nullptr), active(true)
  {
    save_cookies();
  }
 
  Cookie_Saver(const GT & g, Node_Cleanup nc, Arc_Cleanup ac = nullptr)
    : graph(const_cast<GT &>(g)), save_nodes(true), save_arcs(ac != nullptr),
      node_cleanup(std::move(nc)), arc_cleanup(std::move(ac)), active(true)
  {
    save_cookies();
  }
 
  Cookie_Saver(const Cookie_Saver &) = delete;
  Cookie_Saver & operator=(const Cookie_Saver &) = delete;
 
  Cookie_Saver(Cookie_Saver && other) noexcept
    : graph(other.graph),
      saved_node_cookies(std::move(other.saved_node_cookies)),
      saved_arc_cookies(std::move(other.saved_arc_cookies)),
      save_nodes(other.save_nodes), save_arcs(other.save_arcs),
      node_cleanup(std::move(other.node_cleanup)),
      arc_cleanup(std::move(other.arc_cleanup)),
      active(other.active)
  {
    other.active = false;
  }
 
  Cookie_Saver & operator=(Cookie_Saver && other) noexcept
  {
    if (this != &other)
      {
        restore_now();
        saved_node_cookies = std::move(other.saved_node_cookies);
        saved_arc_cookies = std::move(other.saved_arc_cookies);
        save_nodes = other.save_nodes;
        save_arcs = other.save_arcs;
        node_cleanup = std::move(other.node_cleanup);
        arc_cleanup = std::move(other.arc_cleanup);
        active = other.active;
        other.active = false;
      }
    return *this;
  }
 
  void discard() noexcept
  {
    active = false;
    saved_node_cookies.clear();
    saved_arc_cookies.clear();
  }
 
  void restore_now()
  {
    if (not active)
      return;
 
    // First, cleanup current (temporary) cookies if cleanup function provided
    if (node_cleanup)
      {
        for (auto it = graph.get_node_it(); it.has_curr(); it.next_ne())
          node_cleanup(it.get_curr());
      }
 
    if (arc_cleanup)
      {
        for (auto it = graph.get_arc_it(); it.has_curr(); it.next_ne())
          arc_cleanup(it.get_curr());
      }
 
    // Restore saved cookies
    for (auto & [node, cookie] : saved_node_cookies)
      NODE_COOKIE(node) = cookie;
 
    for (auto & [arc, cookie] : saved_arc_cookies)
      ARC_COOKIE(arc) = cookie;
 
    active = false;
    saved_node_cookies.clear();
    saved_arc_cookies.clear();
  }
 
  [[nodiscard]] const std::vector<std::pair<Node*, void*>> & 
  get_saved_node_cookies() const noexcept
  {
    return saved_node_cookies;
  }
 
  [[nodiscard]] const std::vector<std::pair<Arc*, void*>> & 
  get_saved_arc_cookies() const noexcept
  {
    return saved_arc_cookies;
  }
 
  ~Cookie_Saver()
  {
    restore_now();
  }
 
private:
  void save_cookies()
  {
    if (save_nodes)
      {
        saved_node_cookies.reserve(graph.get_num_nodes());
        for (auto it = graph.get_node_it(); it.has_curr(); it.next_ne())
          {
            Node * p = it.get_curr();
            saved_node_cookies.emplace_back(p, NODE_COOKIE(p));
          }
      }
 
    if (save_arcs)
      {
        saved_arc_cookies.reserve(graph.get_num_arcs());
        for (auto it = graph.get_arc_it(); it.has_curr(); it.next_ne())
          {
            Arc * a = it.get_curr();
            saved_arc_cookies.emplace_back(a, ARC_COOKIE(a));
          }
      }
  }
};
 
 
template <class GT, class Func>
auto with_clean_cookies(GT & g, Func && func) -> decltype(func())
{
  Cookie_Guard<GT> guard(g);
  return std::forward<Func>(func)();
}
 
 
template <class GT, class Func>
auto with_saved_cookies(GT & g, Func && func) -> decltype(func())
{
  Cookie_Saver<GT> saver(g);
  return std::forward<Func>(func)();
}
 
 
template <class GT, class Cleanup>
class Scope_Guard
{
  const GT & graph;
  Cleanup cleanup_fn;
  bool active;
 
public:
  Scope_Guard(const GT & g, Cleanup cleanup)
    : graph(g), cleanup_fn(std::move(cleanup)), active(true)
  {}
 
  Scope_Guard(const Scope_Guard &) = delete;
  Scope_Guard & operator=(const Scope_Guard &) = delete;
 
  Scope_Guard(Scope_Guard && other) noexcept
    : graph(other.graph), cleanup_fn(std::move(other.cleanup_fn)),
      active(other.active)
  {
    other.active = false;
  }
 
  ~Scope_Guard()
  {
    if (active)
      cleanup_fn(graph);
  }
 
  void release() noexcept { active = false; }
 
  [[nodiscard]] bool is_active() const noexcept { return active; }
 
  void cleanup_now()
  {
    if (active)
      {
        cleanup_fn(graph);
        active = false;
      }
  }
};
 
template <class GT, class Cleanup>
Scope_Guard(const GT &, Cleanup) -> Scope_Guard<GT, Cleanup>;
 
 
} // end namespace Aleph
 
#endif // COOKIE_GUARD_H