BLI_set_slots.hh

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once

 
#include "BLI_hash_tables.hh"
#include "BLI_memory_utils.hh"
#include "BLI_string_ref.hh"
 
namespace blender {

template<typename Key> class SimpleSetSlot {
 private:
  enum State : uint8_t {
    Empty = 0,
    Occupied = 1,
    Removed = 2,
  };
 
  State state_;
  TypedBuffer<Key> key_buffer_;
 
 public:
  SimpleSetSlot()
  {
    state_ = Empty;
  }

  ~SimpleSetSlot()
  {
    if (state_ == Occupied) {
      key_buffer_.ref().~Key();
    }
  }

  SimpleSetSlot(const SimpleSetSlot &other)
  {
    state_ = other.state_;
    if (other.state_ == Occupied) {
      new (&key_buffer_) Key(*other.key_buffer_);
    }
  }

  SimpleSetSlot(SimpleSetSlot &&other) noexcept(std::is_nothrow_move_constructible_v<Key>)
  {
    state_ = other.state_;
    if (other.state_ == Occupied) {
      new (&key_buffer_) Key(std::move(*other.key_buffer_));
    }
  }

  Key *key()
  {
    return key_buffer_;
  }

  const Key *key() const
  {
    return key_buffer_;
  }

  bool is_occupied() const
  {
    return state_ == Occupied;
  }

  bool is_empty() const
  {
    return state_ == Empty;
  }

  template<typename Hash> uint64_t get_hash(const Hash &hash) const
  {
    BLI_assert(this->is_occupied());
    return hash(*key_buffer_);
  }

  template<typename ForwardKey, typename IsEqual>
  bool contains(const ForwardKey &key, const IsEqual &is_equal, uint64_t /*hash*/) const
  {
    if (state_ == Occupied) {
      return is_equal(key, *key_buffer_);
    }
    return false;
  }

  template<typename ForwardKey> void occupy(ForwardKey &&key, uint64_t /*hash*/)
  {
    BLI_assert(!this->is_occupied());
    new (&key_buffer_) Key(std::forward<ForwardKey>(key));
    state_ = Occupied;
  }

  void remove()
  {
    BLI_assert(this->is_occupied());
    key_buffer_.ref().~Key();
    state_ = Removed;
  }
};

template<typename Key> class HashedSetSlot {
 private:
  enum State : uint8_t {
    Empty = 0,
    Occupied = 1,
    Removed = 2,
  };
 
  uint64_t hash_;
  State state_;
  TypedBuffer<Key> key_buffer_;
 
 public:
  HashedSetSlot()
  {
    state_ = Empty;
  }
 
  ~HashedSetSlot()
  {
    if (state_ == Occupied) {
      key_buffer_.ref().~Key();
    }
  }
 
  HashedSetSlot(const HashedSetSlot &other)
  {
    state_ = other.state_;
    if (other.state_ == Occupied) {
      hash_ = other.hash_;
      new (&key_buffer_) Key(*other.key_buffer_);
    }
  }
 
  HashedSetSlot(HashedSetSlot &&other) noexcept(std::is_nothrow_move_constructible_v<Key>)
  {
    state_ = other.state_;
    if (other.state_ == Occupied) {
      hash_ = other.hash_;
      new (&key_buffer_) Key(std::move(*other.key_buffer_));
    }
  }
 
  Key *key()
  {
    return key_buffer_;
  }
 
  const Key *key() const
  {
    return key_buffer_;
  }
 
  bool is_occupied() const
  {
    return state_ == Occupied;
  }
 
  bool is_empty() const
  {
    return state_ == Empty;
  }
 
  template<typename Hash> uint64_t get_hash(const Hash & /*hash*/) const
  {
    BLI_assert(this->is_occupied());
    return hash_;
  }
 
  template<typename ForwardKey, typename IsEqual>
  bool contains(const ForwardKey &key, const IsEqual &is_equal, const uint64_t hash) const
  {
    /* `hash_` might be uninitialized here, but that is ok. */
    if (hash_ == hash) {
      if (state_ == Occupied) {
        return is_equal(key, *key_buffer_);
      }
    }
    return false;
  }
 
  template<typename ForwardKey> void occupy(ForwardKey &&key, const uint64_t hash)
  {
    BLI_assert(!this->is_occupied());
    new (&key_buffer_) Key(std::forward<ForwardKey>(key));
    state_ = Occupied;
    hash_ = hash;
  }
 
  void remove()
  {
    BLI_assert(this->is_occupied());
    key_buffer_.ref().~Key();
    state_ = Removed;
  }
};

template<typename Key, typename KeyInfo> class IntrusiveSetSlot {
 private:
  Key key_ = KeyInfo::get_empty();
 
 public:
  IntrusiveSetSlot() = default;
  ~IntrusiveSetSlot() = default;
  IntrusiveSetSlot(const IntrusiveSetSlot &other) = default;
  IntrusiveSetSlot(IntrusiveSetSlot &&other) noexcept(std::is_nothrow_move_constructible_v<Key>) =
      default;
 
  Key *key()
  {
    return &key_;
  }
 
  const Key *key() const
  {
    return &key_;
  }
 
  bool is_occupied() const
  {
    return KeyInfo::is_not_empty_or_removed(key_);
  }
 
  bool is_empty() const
  {
    return KeyInfo::is_empty(key_);
  }
 
  template<typename Hash> uint64_t get_hash(const Hash &hash) const
  {
    BLI_assert(this->is_occupied());
    return hash(key_);
  }
 
  template<typename ForwardKey, typename IsEqual>
  bool contains(const ForwardKey &key, const IsEqual &is_equal, const uint64_t /*hash*/) const
  {
    BLI_assert(KeyInfo::is_not_empty_or_removed(key));
    return is_equal(key_, key);
  }
 
  template<typename ForwardKey> void occupy(ForwardKey &&key, const uint64_t /*hash*/)
  {
    BLI_assert(!this->is_occupied());
    BLI_assert(KeyInfo::is_not_empty_or_removed(key));
    key_ = std::forward<ForwardKey>(key);
  }
 
  void remove()
  {
    BLI_assert(this->is_occupied());
    KeyInfo::remove(key_);
  }
};

template<typename Int, Int EmptyValue, Int RemovedValue>
using IntegerSetSlot = IntrusiveSetSlot<Int, TemplatedKeyInfo<Int, EmptyValue, RemovedValue>>;
 
template<typename Key> struct DefaultSetSlot;

template<typename Key> struct DefaultSetSlot {
  using type = SimpleSetSlot<Key>;
};

template<> struct DefaultSetSlot<std::string> {
  using type = HashedSetSlot<std::string>;
};
template<> struct DefaultSetSlot<StringRef> {
  using type = HashedSetSlot<StringRef>;
};
template<> struct DefaultSetSlot<StringRefNull> {
  using type = HashedSetSlot<StringRefNull>;
};

template<typename Key> struct DefaultSetSlot<Key *> {
  using type = IntrusiveSetSlot<Key *, PointerKeyInfo<Key *>>;
};
 
}  // namespace blender