tpl_rand_tree.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
 
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*/
 
 
# ifndef TPL_RAND_TREE_H
# define TPL_RAND_TREE_H
 
# include <ctime>
# include <climits>
# include <gsl/gsl_rng.h>
# include <ahUtils.H>
# include <ahFunction.H>
# include <tpl_randNode.H>
# include <tpl_binTreeOps.H>
# include <ah-errors.H>
 
using namespace Aleph;
 
namespace Aleph
{
  template <template <typename> class NodeType, typename Key, class Compare>
  class Gen_Rand_Tree
  {
  public:
    using Node = NodeType<Key>; 
 
  private:
    Node *tree_root;
    gsl_rng *r;
    Compare cmp;
 
    Node * random_insert(Node *root, Node *p) noexcept
    {
      if (root == Node::NullPtr)
        return p;
 
      // Prefetch children to reduce memory latency
      __builtin_prefetch(LLINK(root));
      __builtin_prefetch(RLINK(root));
 
      const long n = COUNT(root);
      if (const size_t rn = gsl_rng_uniform_int(r, n + 1); rn == n) [[unlikely]]
          return BinTreeXt_Operation<Node, Compare>(cmp).insert_root(root, p);
 
      Node *result;
      const Key & pk = KEY(p);
      const Key & rk = KEY(root);
      if (cmp(pk, rk)) // KEY(p) < KEY(root)
        {
          result = random_insert(LLINK(root), p);
          if (result != Node::NullPtr) // p was inserted
            {
              LLINK(root) = result;
              ++COUNT(root);
              return root;
            }
        }
      else if (cmp(rk, pk)) // KEY(p) > KEY(root)
        {
          result = random_insert(RLINK(root), p);
          if (result != Node::NullPtr) // p was inserted
            {
              RLINK(root) = result;
              ++COUNT(root);
              return root;
            }
        }
 
      return Node::NullPtr; // duplicated key ==> no insertion
    }
 
    Node * random_insert_dup(Node *root, Node *p) noexcept
    {
      if (root == Node::NullPtr)
        return p;
 
      // Prefetch children to reduce memory latency
      __builtin_prefetch(LLINK(root));
      __builtin_prefetch(RLINK(root));
 
      const long n = COUNT(root);
      if (const size_t rn = gsl_rng_uniform_int(r, n + 1); rn == n) [[unlikely]]
          return BinTreeXt_Operation<Node, Compare>(cmp).insert_dup_root(root, p);
 
      const Key & pk = KEY(p);
      const Key & rk = KEY(root);
      if (cmp(pk, rk)) // KEY(p) < KEY(root)
        LLINK(root) = random_insert_dup(LLINK(root), p);
      else
        RLINK(root) = random_insert_dup(RLINK(root), p);
 
      ++COUNT(root);
 
      return root;
    }
 
    Node * random_search_or_insert(Node *& root, Node *p) noexcept
    {
      if (root == Node::NullPtr)
        return root = p;
 
      // Prefetch children to reduce memory latency
      if (LLINK(root) != Node::NullPtr)
        __builtin_prefetch(LLINK(root));
      if (RLINK(root) != Node::NullPtr)
        __builtin_prefetch(RLINK(root));
 
      const long n = COUNT(root);
      if (const size_t rn = gsl_rng_uniform_int(r, n + 1); rn == n) [[unlikely]]
        {
          if (BinTreeXt_Operation<Node, Compare>(cmp).insert_root(root, p) != Node::NullPtr)
            return p;
 
          return searchInBinTree<Node, Compare>(root, KEY(p), cmp);
        }
 
      const Key & pk = KEY(p);
      const Key & rk = KEY(root);
      if (cmp(pk, rk))
        {
          Node *ret = random_search_or_insert(LLINK(root), p);
          if (ret == p)
            ++COUNT(root);
 
          return ret;
        }
      if (cmp(rk, pk))
        {
          Node *ret = random_search_or_insert(RLINK(root), p);
          if (ret == p)
            ++COUNT(root);
 
          return ret;
        }
 
      return root; // key == root: found existing
    }
 
  public:
    Gen_Rand_Tree(const Gen_Rand_Tree &) = delete;
 
    Gen_Rand_Tree &operator =(const Gen_Rand_Tree &) = delete;
 
  private:
    void init(const unsigned long seed)
    {
      r = gsl_rng_alloc(gsl_rng_mt19937);
 
      ah_bad_alloc_if(r == nullptr);
 
      gsl_rng_set(r, seed % gsl_rng_max(r));
    }
 
  public:
    Compare &key_comp() noexcept { return cmp; }
 
    const Compare &key_comp() const noexcept { return cmp; }
 
    Compare &get_compare() noexcept { return key_comp(); }
 
    const Compare &get_compare() const noexcept { return cmp; }
 
    gsl_rng * gsl_rng_object() noexcept { return r; }
 
    void set_seed(const unsigned long seed) noexcept
    {
      gsl_rng_set(r, seed % gsl_rng_max(r));
    }
 
    Gen_Rand_Tree(const unsigned int seed, const Compare & __cmp = Compare())
      : tree_root(Node::NullPtr), r(nullptr), cmp(__cmp)
    {
      init(seed);
    }
 
    Gen_Rand_Tree(const Compare & cmp = Compare()) noexcept
      : Gen_Rand_Tree(time(nullptr), cmp)
    { /* empty */
    }
 
    void swap(Gen_Rand_Tree & tree) noexcept
    {
      std::swap(tree_root, tree.tree_root);
      std::swap(r, tree.r);
      std::swap(cmp, tree.cmp);
    }
 
    Gen_Rand_Tree(Gen_Rand_Tree && other) noexcept
      : tree_root(other.tree_root), r(other.r), cmp(std::move(other.cmp))
    {
      other.tree_root = Node::NullPtr;
      other.r = nullptr;
    }
 
    Gen_Rand_Tree &operator =(Gen_Rand_Tree && other) noexcept
    {
      if (this != &other)
        {
          // Clean up current resources
          if (r != nullptr)
            gsl_rng_free(r);
          destroyRec(tree_root);
 
          // Transfer ownership
          tree_root = other.tree_root;
          r = other.r;
          cmp = std::move(other.cmp);
 
          // Reset other
          other.tree_root = Node::NullPtr;
          other.r = nullptr;
        }
      return *this;
    }
 
    virtual ~Gen_Rand_Tree() noexcept
    {
      if (r != nullptr)
        gsl_rng_free(r);
      // Note: nodes are NOT freed here. DynSetTree::empty() handles node deletion.
      // The underlying tree only manages the tree structure, not node memory.
    }
 
    Node * insert(Node *p) noexcept
    {
      assert(p != Node::NullPtr);
      assert((LLINK(p) == Node::NullPtr) and (RLINK(p) == Node::NullPtr));
      assert(COUNT(p) == 1);
 
      Node *result = random_insert(tree_root, p);
      if (result == Node::NullPtr)
        return nullptr;
 
      return tree_root = result;
    }
 
    Node * insert_dup(Node *p) noexcept
    {
      assert(p != Node::NullPtr);
      assert((LLINK(p) == Node::NullPtr) and (RLINK(p) == Node::NullPtr));
      assert(COUNT(p) == 1);
 
      return tree_root = random_insert_dup(tree_root, p);
    }
 
  private:
    Node * random_join_exclusive(Node *tl, Node *tr) noexcept
    {
      if (tl == Node::NullPtr)
        return tr;
 
      if (tr == Node::NullPtr)
        return tl;
 
      const size_t & m = COUNT(tl);
      const size_t & n = COUNT(tr);
      if (const size_t rn = 1 + gsl_rng_uniform_int(r, m + n); rn <= m)
        { // left subtree wins
          COUNT(tl) += COUNT(tr);
          RLINK(tl) = random_join_exclusive(RLINK(tl), tr);
          return tl;
        }
      COUNT(tr) += COUNT(tl);
      LLINK(tr) = random_join_exclusive(tl, LLINK(tr));
      return tr;
    }
 
    Node * random_remove(Node *& root, const Key & key) noexcept
    {
      if (root == Node::NullPtr)
        return Node::NullPtr;
 
      Node *ret_val;
      const Key & rk = KEY(root);
      if (cmp(key, rk))
        {
          ret_val = random_remove(LLINK(root), key);
          if (ret_val != Node::NullPtr)
            --COUNT(root);
 
          return ret_val;
        }
      if (cmp(rk, key))
        {
          ret_val = random_remove(RLINK(root), key);
          if (ret_val != Node::NullPtr)
            --COUNT(root);
 
          return ret_val;
        }
 
      // key was found
      ret_val = root;
      root = random_join_exclusive(LLINK(root), RLINK(root));
      ret_val->reset();
 
      return ret_val;
    }
 
  public:
    Node * remove(const Key & key) noexcept
    {
      Node *ret_val = random_remove(tree_root, key);
 
      return ret_val != Node::NullPtr ? ret_val : nullptr;
    }
 
    Node * search(const Key & key) const noexcept
    {
      Node *retVal = searchInBinTree<Node, Compare>(tree_root, key, cmp);
      return retVal == Node::NullPtr ? nullptr : retVal;
    }
 
    Node * search_or_insert(Node *p) noexcept
    {
      assert(p != Node::NullPtr);
      assert(COUNT(p) == 1);
 
      return random_search_or_insert(tree_root, p);
    }
 
    [[nodiscard]] bool verify() const
    {
      return check_rank_tree(tree_root);
    }
 
    Node *&getRoot() noexcept { return tree_root; }
 
    Node * select(const size_t i) const
    {
      return Aleph::select(tree_root, i);
    }
 
    [[nodiscard]] size_t size() const noexcept { return COUNT(tree_root); }
 
    [[nodiscard]] bool is_empty() const noexcept { return tree_root == Node::NullPtr; }
 
    std::pair<long, Node *> position(const Key & key) const noexcept
    {
      std::pair<long, Node *> ret_val;
      ret_val.first = BinTreeXt_Operation<Node, Compare>(cmp).
          inorder_position(tree_root, key, ret_val.second);
 
      return ret_val;
    }
 
    std::pair<long, Node *> find_position(const Key & key) const noexcept
    {
      std::pair<long, Node *> r(-2, nullptr);
 
      r.first = BinTreeXt_Operation<Node, Compare>(cmp).
          find_position(tree_root, key, r.second);
 
      return r;
    }
 
  private:
    Node * remove_pos(Node *& root, const size_t pos) noexcept
    {
      if (pos == COUNT(LLINK(root)))
        {
          Node *ret_val = root;
          root = random_join_exclusive(LLINK(ret_val), RLINK(ret_val));
          return ret_val;
        }
 
      --COUNT(root);
      if (pos < COUNT(LLINK(root)))
        return remove_pos(LLINK(root), pos);
      else
        return remove_pos(RLINK(root), pos - COUNT(LLINK(root)) - 1);
    }
 
  public:
    Node * remove_pos(const size_t i)
    {
      ah_out_of_range_error_if(i >= COUNT(tree_root)) << "infix position out of range";
 
      return remove_pos(tree_root, i);
    }
 
    bool split_key(const Key & key, Gen_Rand_Tree & t1, Gen_Rand_Tree & t2)
      noexcept
    {
      return split_key_rec_xt(tree_root, key, t1.getRoot(), t2.getRoot());
    }
 
    void split_key_dup(const Key & key, Gen_Rand_Tree & t1, Gen_Rand_Tree & t2)
      noexcept
    {
      split_key_dup_rec_xt(tree_root, key, t1.getRoot(), t2.getRoot());
    }
 
    void split_pos(size_t pos, Gen_Rand_Tree & t1, Gen_Rand_Tree & t2) noexcept
    {
      split_pos_rec(tree_root, pos, t1.getRoot(), t2.getRoot());
    }
 
  private:
    Node * random_join(Node *t1, Node *t2, Node *& dup)
    {
      if (t1 == Node::NullPtr)
        return t2;
 
      if (t2 == Node::NullPtr)
        return t1;
 
      Node *ret = Node::NullPtr;
      const size_t m = COUNT(t1);
      const size_t n = COUNT(t2);
      if (const size_t rn = 1 + gsl_rng_uniform_int(r, m + n); rn <= m)
        { // root of t1 wins
          Node *l = LLINK(t1), *r = RLINK(t1);
          t1->reset();
        t1_wins:
          ret = insert_root_xt(t2, t1, cmp);
          if (ret != Node::NullPtr)
            {
              LLINK(ret) = random_join(LLINK(ret), l, dup);
              RLINK(ret) = random_join(RLINK(ret), r, dup);
              COUNT(ret) = COUNT(LLINK(ret)) + 1 + COUNT(RLINK(ret));
            }
          else
            {
              dup = random_insert_dup(dup, random_remove(t2, KEY(t1)));
              goto t1_wins;
            }
        }
      else
        { // root of t2 wins
          Node *l = LLINK(t2), *r = RLINK(t2);
          t2->reset();
        t2_wins:
          ret = insert_root_xt(t1, t2, cmp);
          if (ret != Node::NullPtr)
            {
              LLINK(ret) = random_join(l, LLINK(ret), dup);
              RLINK(ret) = random_join(r, RLINK(ret), dup);
              COUNT(ret) = COUNT(LLINK(ret)) + 1 + COUNT(RLINK(ret));
            }
          else
            {
              dup = random_insert_dup(dup, random_remove(t1, KEY(t2)));
              goto t2_wins;
            }
        }
 
      return ret;
    }
 
    Node * random_join(Node *t1, Node *t2)
    {
      if (t1 == Node::NullPtr)
        return t2;
 
      if (t2 == Node::NullPtr)
        return t1;
 
      Node *ret = Node::NullPtr;
      const size_t & m = COUNT(t1);
      const size_t & n = COUNT(t2);
      const size_t total = m + n;
      if (const size_t rn = 1 + gsl_rng_uniform_int(r, total); rn <= m)
        { // root of t1 wins
          Node *l = LLINK(t1), *r = RLINK(t1);
          t1->reset();
          ret = insert_dup_root_xt(t2, t1, cmp);
          LLINK(ret) = random_join(LLINK(ret), l);
          RLINK(ret) = random_join(RLINK(ret), r);
        }
      else
        { // root of t2 wins
          Node *l = LLINK(t2), *r = RLINK(t2);
          t2->reset();
          ret = insert_dup_root_xt(t1, t2, cmp);
          LLINK(ret) = random_join(l, LLINK(ret));
          RLINK(ret) = random_join(r, RLINK(ret));
        }
 
      COUNT(ret) = total;
      return ret;
    }
 
  public:
    void join(Gen_Rand_Tree & t, Gen_Rand_Tree & dup) noexcept
    {
      tree_root = random_join(tree_root, t.tree_root, dup.tree_root);
      t.tree_root = Node::NullPtr;
    }
 
    void join_dup(Gen_Rand_Tree & t) noexcept
    {
      tree_root = random_join(tree_root, t.tree_root);
      t.tree_root = Node::NullPtr;
    }
 
    void join_exclusive(Gen_Rand_Tree & t) noexcept
    {
      tree_root = random_join_exclusive(tree_root, t.tree_root);
      t.tree_root = Node::NullPtr;
    }
 
    struct Iterator : public BinNodeInfixIterator<Node>
    {
      Iterator(Gen_Rand_Tree & t) : BinNodeInfixIterator<Node>(t.getRoot()) {}
    };
  };
 
  template <typename Key, class Compare = Aleph::less<Key>>
  struct Rand_Tree : public Gen_Rand_Tree<RandNode, Key, Compare>
  {
    using Base = Gen_Rand_Tree<RandNode, Key, Compare>;
    using Base::Base;
  };
 
 
  template <typename Key, class Compare = Aleph::less<Key>>
  struct Rand_Tree_Vtl : public Gen_Rand_Tree<RandNodeVtl, Key, Compare>
  {
    using Base = Gen_Rand_Tree<RandNodeVtl, Key, Compare>;
    using Base::Base;
  };
} // end namespace Aleph
 
# endif // TPL_RAND_TREE_H