tpl_agraph.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 TPL_AGRAPH_H
# define TPL_AGRAPH_H
 
# include <tpl_dynSetTree.H>
# include <array_it.H>
# include <tpl_sgraph.H>
# include <ah-errors.H>
 
namespace Aleph
{
  using namespace Aleph;
 
  template <typename Node_Info = Empty_Class>
  class Graph_Anode
      : public Dlink,
        public GTNodeCommon<Node_Info>
  {
    using Base = GTNodeCommon<Node_Info>;
    friend class GTNodeCommon<Node_Info>;
 
    static constexpr size_t Contract_Factor = 4;
    static constexpr size_t Default_Cap = 4;
 
    void init(const size_t dim)
    {
      arcs_dim = dim;
      this->num_arcs = 0;
      contract_threshold = arcs_dim / Contract_Factor;
      arc_array = nullptr;
      if (arcs_dim == 0)
        return;
 
      arc_array = static_cast<void **>(malloc(arcs_dim * sizeof(void *)));
      ah_bad_alloc_if(arc_array == nullptr);
    }
 
  public:
    void **arc_array = nullptr;
    size_t arcs_dim = 0;
    size_t contract_threshold = 0;
 
    Graph_Anode()
    {
      init(0);
    }
 
    Graph_Anode(const Node_Info & info) : Base(info)
    {
      init(Default_Cap);
    }
 
    Graph_Anode(Node_Info && info) : Base(std::move(info))
    {
      init(Default_Cap);
    }
 
    Graph_Anode(const Graph_Anode & node) : Dlink(), Base(node.node_info)
    {
      init(0);
    }
 
    Graph_Anode &operator =(const Graph_Anode & node)
    {
      if (&node == this)
        return *this;
      this->node_info = node.node_info;
      return *this;
    }
 
    Graph_Anode(Graph_Anode *p) : Base(p->get_info())
    {
      init(0);
    }
 
    virtual ~Graph_Anode()
    {
      if (arc_array != nullptr)
        free(arc_array);
    }
 
    void allocate_more(size_t new_size)
    {
      if (new_size == 0)
        new_size = 1;
 
      const auto new_array = static_cast<void **>(realloc(arc_array, new_size * sizeof(void *)));
      ah_bad_alloc_if(new_array == nullptr);
 
      arc_array = new_array;
      arcs_dim = new_size;
      contract_threshold = arcs_dim / Contract_Factor;
    }
 
    void * insert_arc(void * arc) 
    {
      // Defensive: adjacency storage must be consistent before insertion.
      // If any invariant is broken, reset and reallocate using malloc.
      // NOTE: Do NOT free arc_array here - if we hit this condition, arc_array
      // likely contains garbage from uninitialized memory (not a valid allocation).
      if (arc_array == nullptr or arcs_dim == 0 or this->num_arcs > arcs_dim)
        {
          arc_array = static_cast<void **>(malloc(Default_Cap * sizeof(void *)));
          ah_bad_alloc_if(arc_array == nullptr);
          arcs_dim = Default_Cap;
          contract_threshold = arcs_dim / Contract_Factor;
          this->num_arcs = 0;
        }
 
      if (this->num_arcs == arcs_dim)
        allocate_more(arcs_dim << 1); // 2*arcs_dim
    
      arc_array[this->num_arcs++] = arc;
 
      return arc;
    }
 
    void remove_arc_ne(const void *arc) noexcept
    {
      for (size_t i = 0; i < this->num_arcs; ++i)
        if (arc_array[i] == arc)
          {
            arc_array[i] = arc_array[--(this->num_arcs)];
            break;
          }
 
      if (this->num_arcs > contract_threshold)
        return;
 
      // contraction
      const size_t new_sz = arcs_dim >> 1; // num_arcs/2
      arc_array = static_cast<void **>(realloc(arc_array, new_sz * sizeof(void *)));
      arcs_dim = new_sz;
      contract_threshold = arcs_dim / Contract_Factor;
    }
 
    void remove_arc(const void *arc)
    {
      bool removed = false;
      for (size_t i = 0; i < this->num_arcs; ++i)
        if (arc_array[i] == arc)
          {
            arc_array[i] = arc_array[--(this->num_arcs)];
            removed = true;
            break;
          }
 
      ah_domain_error_if(not removed) << "arc for deleting not found";
 
      if (this->num_arcs > contract_threshold)
        return;
 
      // contraction
      const size_t new_sz = arcs_dim >> 1; // num_arcs/2
      arc_array = static_cast<void **>(realloc(arc_array, new_sz * sizeof(void *)));
      arcs_dim = new_sz;
      contract_threshold = arcs_dim / Contract_Factor;
    }
 
    bool compress() noexcept
    {
      const auto new_array = static_cast<void **>(realloc(arc_array,
                                                          this->num_arcs * sizeof(void *)));
      if (new_array == nullptr)
        return false;
 
      arc_array = new_array;
      arcs_dim = this->num_arcs;
      contract_threshold = this->num_arcs / Contract_Factor;
 
      return true;
    }
  };
 
 
  template <typename Arc_Info = Empty_Class>
  class Graph_Aarc
      : public Dlink,
        public GTArcCommon<Arc_Info>
  {
    friend class GTArcCommon<Arc_Info>;
    using Base = GTArcCommon<Arc_Info>;
 
  public:
    Graph_Aarc(const Arc_Info & info)
      : Base(info)
    {
      /* empty */
    }
 
    Graph_Aarc(Arc_Info && info = Arc_Info())
      : Base(std::move(info))
    {
      /* empty */
    }
 
    Graph_Aarc(const Graph_Aarc & arc)
      : Graph_Aarc(arc.arc_info)
    { /* empty */
    }
 
    Graph_Aarc &operator =(const Graph_Aarc & arc)
    {
      if (&arc == this)
        return *this;
      this->arc_info = arc.arc_info;
      return *this;
    }
 
    Graph_Aarc(void *src, void *tgt, const Arc_Info & data)
      : Base(src, tgt, data)
    {
      // empty
    }
 
    Graph_Aarc(void *src, void *tgt, Arc_Info && data = Arc_Info())
      : Base(src, tgt, std::move(data))
    {
      // empty
    }
  };
 
 
  template <class __Graph_Node = Graph_Anode<unsigned long>,
            class __Graph_Arc = Graph_Aarc<unsigned long>>
  class Array_Graph
      : public GraphCommon<Array_Graph<__Graph_Node, __Graph_Arc>,
                           __Graph_Node, __Graph_Arc>
  {
  public:
    using Node = __Graph_Node;
    using Arc = __Graph_Arc;
    using Node_Type = typename Node::Node_Type;
    using Arc_Type = typename Arc::Arc_Type;
 
    friend class GraphCommon<Array_Graph<__Graph_Node, __Graph_Arc>,
                             __Graph_Node, __Graph_Arc>;
 
    using CommonBase = GraphCommon<Array_Graph<__Graph_Node, __Graph_Arc>,
                                   __Graph_Node, __Graph_Arc>;
 
    using CommonBase::insert_node;
    using CommonBase::insert_arc;
 
  private:
    // using DynSetNode = DynSetTree<Node*, Avl_Tree>;
    using DynSetArc = DynSetTree<Arc *, Rand_Tree>;
 
    Dlink node_set;
    Dlink arc_set;
 
  public:
    Dlink & get_node_dlink() noexcept { return node_set; }
 
    Dlink & get_arc_dlink() noexcept { return arc_set; }
 
    struct Node_Iterator : public GTNodeIterator<Array_Graph>
    {
      using Base = GTNodeIterator<Array_Graph>;
      using Base::Base;
 
      Node_Iterator(const Array_Graph & g) noexcept
        : Base(const_cast<Dlink &>(g.node_set))
      {
        // empty
      }
    };
 
    struct Arc_Iterator : public GTArcIterator<Array_Graph>
    {
      using Base = GTArcIterator<Array_Graph>;
      using Base::Base;
 
      Arc_Iterator(const Array_Graph & g)
        : Base(const_cast<Dlink &>(g.arc_set))
      {
        // empty
      }
    };
 
    class Node_Arc_Iterator : public Array_Iterator<void *>
    {
      Node *src_node = nullptr;
 
    public:
      using Item_Type = Arc *;
 
      using Set_Type = Node *;
 
      Node_Arc_Iterator() noexcept
      { /* empty */
      }
 
      Node_Arc_Iterator(Node *src) noexcept
        : Array_Iterator<void *>(no_exception_ctor,
                                 src->arc_array, src->arcs_dim, src->num_arcs),
          src_node(src)
      {
        // empty
      }
 
      Arc * get_curr() const
      {
        return static_cast<Arc *>(const_cast<Node_Arc_Iterator *>(this)->
          Array_Iterator<void *>::get_curr());
      }
 
      Arc * get_curr_ne() const noexcept
      {
        return static_cast<Arc *>(const_cast<Node_Arc_Iterator *>(this)->
          Array_Iterator<void *>::get_curr_ne());
      }
 
      Arc * get_current_arc_ne() const noexcept { return get_curr_ne(); }
 
      Arc * get_current_arc() const { return get_curr(); }
 
      Node * get_tgt_node_ne() const
      {
        Arc *a = get_curr_ne();
        return static_cast<Node *>(a->get_connected_node(src_node));
      }
 
      Node * get_tgt_node() const
      {
        Arc *a = get_curr();
        return static_cast<Node *>(a->get_connected_node(src_node));
      }
    };
 
    virtual Node * insert_node(Node *p)
    {
      assert(p != nullptr);
      assert(p->num_arcs == 0);
 
      node_set.append(p);
      ++this->num_nodes;
 
      return p;
    }
 
    void compress()
    {
      for (Node_Iterator it(*this); it.has_curr(); it.next_ne())
        it.get_curr()->compress();
    }
 
  private:
    Arc * try_insert_arc(Node *src, Node *tgt, void *a)
    {
      Arc *aptr = static_cast<Arc *>(a);
 
      aptr->src_node = src;
      aptr->tgt_node = tgt;
      src->insert_arc(aptr);
 
      if (not this->digraph and src != tgt)
        {
          try
            {
              tgt->insert_arc(aptr);
            }
          catch (const std::bad_alloc &)
            {
              src->remove_arc(aptr);
              throw;
            }
        }
 
      try
        {
          arc_set.append(aptr);
          ++this->num_arcs;
        }
      catch (const std::bad_alloc &)
        {
          src->remove_arc(aptr);
          if (not this->digraph and src != tgt)
            tgt->remove_arc(aptr);
          throw;
        }
 
      return aptr;
    }
 
  public:
    Arc * connect_arc(Arc *arc)
    {
      return
          try_insert_arc(this->get_src_node(arc), this->get_tgt_node(arc), arc);
    }
 
  private:
    Arc * insert_arc(Node *src, Node *tgt, void *a)
    {
      bool compress_done = false;
 
    retry:
      try
        {
          return try_insert_arc(src, tgt, a);
        }
      catch (const std::bad_alloc &)
        {
          if (compress_done)
            throw;
 
          compress();
          compress_done = true;
          goto retry;
        }
    }
 
  public:
    Arc * disconnect_arc(Arc *arc)
    {
      Node *src = static_cast<Node *>(arc->src_node);
      Node *tgt = static_cast<Node *>(arc->tgt_node);
 
      src->remove_arc_ne(arc);
      if (not this->digraph and src != tgt)
        tgt->remove_arc_ne(arc);
 
      arc->del(); // delete it from arc_set
      --this->num_arcs;
 
      return arc;
    }
 
    virtual void remove_arc(Arc *a)
    {
      delete disconnect_arc(a);
    }
 
    virtual void remove_node(Node *p)
    {
      if (this->digraph)
        // traverse all arcs of graph and remove those whose source or target is p
        this->remove_arcs_if([p, this](auto arc) {
          return this->get_src_node(arc) == p or this->get_tgt_node(arc) == p;
        });
      else
        {
          // traverse arcs of node (collect then delete for safe iteration)
          DynList<Arc *> arcs;
          for (size_t i = 0, n = p->num_arcs; i < n; ++i)
            arcs.append(static_cast<Arc *>(p->arc_array[i]));
          arcs.for_each([this](auto arc) { this->remove_arc(arc); });
        }
 
      p->del(); // remove from node_set
      --this->num_nodes;
 
      delete p;
    }
 
    Node * get_first_node() const
    {
      return static_cast<Node *>(node_set.get_first());
    }
 
    Arc * get_first_arc() const
    {
      return static_cast<Arc *>(arc_set.get_first());
    }
 
    Arc * get_first_arc(Node *p) const
    {
      ah_range_error_if(this->get_num_arcs(p) == 0) << "Node has no arcs";
      return static_cast<Arc *>(p->arc_array[0]);
    }
 
    Array_Graph()
    {
      assert(this->num_nodes == 0 and this->num_arcs == 0 and
             node_set.is_empty() and arc_set.is_empty());
    }
 
  private:
    void clear() noexcept
    {
      while (not arc_set.is_empty())
        delete static_cast<Arc *>(arc_set.remove_first());
 
      while (not node_set.is_empty())
        delete static_cast<Node *>(node_set.remove_first());
 
      this->num_nodes = this->num_arcs = 0;
    }
 
  public:
    virtual ~Array_Graph() noexcept
    {
      clear();
    }
 
    void swap(Array_Graph & g) noexcept
    {
      this->common_swap(g);
      node_set.swap(g.node_set);
      arc_set.swap(g.arc_set);
    }
 
    ALEPH_GRAPH_COPY_MOVE_CTORS(Array_Graph)
 
  private:
    template <class Cmp>
    struct Cmp_Arc
    {
      Cmp & cmp;
 
      Cmp_Arc(Cmp && __cmp = Cmp())
        : cmp(__cmp)
      { /* empty */
      }
 
      Cmp_Arc(Cmp & __cmp)
        : cmp(__cmp)
      { /* empty */
      }
 
      bool operator ()(Arc *a1, Arc *a2) const noexcept
      {
        return cmp(a1, a2);
      }
    };
 
    // sort_nodes() and sort_arcs() are inherited from GraphCommon via CRTP
    // They use the get_node_dlink() and get_arc_dlink() accessors defined above
  };
 
  template <typename __Graph_Node = Graph_Anode<int>,
            typename __Graph_Arc = Graph_Aarc<int>>
  using Array_Digraph = Digraph<Array_Graph<__Graph_Node, __Graph_Arc>>;
 
} // namespace Aleph {
 
# endif //  TPL_AGRAPH_H