tornavis/source/blender/blenlib/BLI_generic_value_map.hh

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

#pragma once

#include "BLI_generic_pointer.hh"
#include "BLI_linear_allocator.hh"
#include "BLI_map.hh"

namespace blender {

/**
 * This is a map that stores key-value-pairs. What makes it special is that the type of values does
 * not have to be known at compile time. There just has to be a corresponding CPPType.
 */
template<typename Key> class GValueMap {
 private:
  /* Used to allocate values owned by this container. */
  LinearAllocator<> &allocator_;
  Map<Key, GMutablePointer> values_;

 public:
  GValueMap(LinearAllocator<> &allocator) : allocator_(allocator) {}

  ~GValueMap()
  {
    /* Destruct all values that are still in the map. */
    for (GMutablePointer value : values_.values()) {
      value.destruct();
    }
  }

  /* Add a value to the container. The container becomes responsible for destructing the value that
   * is passed in. The caller remains responsible for freeing the value after it has been
   * destructed. */
  template<typename ForwardKey> void add_new_direct(ForwardKey &&key, GMutablePointer value)
  {
    values_.add_new_as(std::forward<ForwardKey>(key), value);
  }

  /* Add a value to the container that is move constructed from the given value. The caller remains
   * responsible for destructing and freeing the given value. */
  template<typename ForwardKey> void add_new_by_move(ForwardKey &&key, GMutablePointer value)
  {
    const CPPType &type = *value.type();
    void *buffer = allocator_.allocate(type.size(), type.alignment());
    type.move_construct(value.get(), buffer);
    values_.add_new_as(std::forward<ForwardKey>(key), GMutablePointer{type, buffer});
  }

  /* Add a value to the container that is copy constructed from the given value. The caller remains
   * responsible for destructing and freeing the given value. */
  template<typename ForwardKey> void add_new_by_copy(ForwardKey &&key, GPointer value)
  {
    const CPPType &type = *value.type();
    void *buffer = allocator_.allocate(type.size(), type.alignment());
    type.copy_construct(value.get(), buffer);
    values_.add_new_as(std::forward<ForwardKey>(key), GMutablePointer{type, buffer});
  }

  /* Add a value to the container. */
  template<typename ForwardKey, typename T> void add_new(ForwardKey &&key, T &&value)
  {
    if constexpr (std::is_rvalue_reference_v<T>) {
      this->add_new_by_move(std::forward<ForwardKey>(key), &value);
    }
    else {
      this->add_new_by_copy(std::forward<ForwardKey>(key), &value);
    }
  }

  /* Remove the value for the given name from the container and remove it. The caller is
   * responsible for freeing it. The lifetime of the referenced memory might be bound to lifetime
   * of the container. */
  template<typename ForwardKey> GMutablePointer extract(const ForwardKey &key)
  {
    return values_.pop_as(key);
  }

  template<typename ForwardKey> GPointer lookup(const ForwardKey &key) const
  {
    return values_.lookup_as(key);
  }

  /* Remove the value for the given name from the container and remove it. */
  template<typename T, typename ForwardKey> T extract(const ForwardKey &key)
  {
    GMutablePointer value = values_.pop_as(key);
    const CPPType &type = *value.type();
    BLI_assert(type.is<T>());
    T return_value;
    type.relocate_assign(value.get(), &return_value);
    return return_value;
  }

  template<typename T, typename ForwardKey> const T &lookup(const ForwardKey &key) const
  {
    GMutablePointer value = values_.lookup_as(key);
    BLI_assert(value.is_type<T>());
    BLI_assert(value.get() != nullptr);
    return *(const T *)value.get();
  }

  template<typename ForwardKey> bool contains(const ForwardKey &key) const
  {
    return values_.contains_as(key);
  }
};

}  // namespace blender