allocator.h

// Copyright 2023 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#pragma once
 
#include <cstddef>
 
#include "pw_allocator/capability.h"
#include "pw_allocator/deallocator.h"
#include "pw_allocator/internal/control_block.h"
#include "pw_allocator/layout.h"
#include "pw_allocator/shared_ptr.h"
#include "pw_allocator/unique_ptr.h"
#include "pw_numeric/checked_arithmetic.h"
#include "pw_result/result.h"
 
namespace pw {
 
class Allocator : public Deallocator {
 private:
  using ControlBlock = allocator::internal::ControlBlock;
 
 public:
  void* Allocate(Layout layout) {
    return layout.size() != 0 ? DoAllocate(layout) : nullptr;
  }
 
  template <typename T, int&... kExplicitGuard, typename... Args>
  [[nodiscard]] std::enable_if_t<!std::is_array_v<T>, T*> New(Args&&... args) {
    void* ptr = Allocate(Layout::Of<T>());
    if (ptr == nullptr) {
      return nullptr;
    }
    return new (ptr) T(std::forward<Args>(args)...);
  }
 
  template <typename T,
            int&... kExplicitGuard,
            typename ElementType = std::remove_extent_t<T>,
            std::enable_if_t<is_unbounded_array_v<T>, int> = 0>
  [[nodiscard]] ElementType* New(size_t count) {
    return New<T>(count, alignof(ElementType));
  }
 
  template <typename T,
            int&... kExplicitGuard,
            typename ElementType = std::remove_extent_t<T>,
            std::enable_if_t<is_unbounded_array_v<T>, int> = 0>
  [[nodiscard]] ElementType* New(size_t count, size_t alignment) {
    void* ptr = Allocate(Layout::Of<T>(count).Align(alignment));
    return ptr != nullptr ? new (ptr) ElementType[count] : nullptr;
  }
 
  template <typename T>
  T* NewArray(size_t count) {
    return New<T[]>(count, alignof(T));
  }
 
  template <typename T>
  T* NewArray(size_t count, size_t alignment) {
    return New<T[]>(count, alignment);
  }
 
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<!std::is_array_v<T>, int> = 0,
            typename... Args>
  [[nodiscard]] UniquePtr<T> MakeUnique(Args&&... args) {
    return Deallocator::WrapUnique<T>(New<T>(std::forward<Args>(args)...));
  }
 
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<is_unbounded_array_v<T>, int> = 0>
  [[nodiscard]] UniquePtr<T> MakeUnique(size_t size) {
    return MakeUnique<T>(size, alignof(std::remove_extent_t<T>));
  }
 
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<is_unbounded_array_v<T>, int> = 0>
  [[nodiscard]] UniquePtr<T> MakeUnique(size_t size, size_t alignment) {
    return Deallocator::WrapUnique<T>(New<T>(size, alignment), size);
  }
 
  template <typename T>
  [[nodiscard]] UniquePtr<T[]> MakeUniqueArray(size_t size) {
    return MakeUnique<T[]>(size, alignof(std::remove_extent_t<T>));
  }
 
  template <typename T>
  [[nodiscard]] UniquePtr<T[]> MakeUniqueArray(size_t size, size_t alignment) {
    return MakeUnique<T[]>(size, alignment);
  }
 
  // Disallow calls with explicitly-sized array types like `T[kN]`.
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<is_bounded_array_v<T>, int> = 0,
            typename... Args>
  void MakeUnique(Args&&...) = delete;
 
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<!std::is_array_v<T>, int> = 0,
            typename... Args>
  [[nodiscard]] SharedPtr<T> MakeShared(Args&&... args) {
    auto* control_block = ControlBlock::Create(this, Layout::Of<T>(), 1);
    if (control_block == nullptr) {
      return nullptr;
    }
    auto* t = new (control_block->data()) T(std::forward<Args>(args)...);
    return SharedPtr<T>(t, control_block);
  }
 
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<is_unbounded_array_v<T>, int> = 0>
  [[nodiscard]] SharedPtr<T> MakeShared(size_t size) {
    return MakeShared<T>(size, alignof(std::remove_extent_t<T>));
  }
 
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<is_unbounded_array_v<T>, int> = 0>
  [[nodiscard]] SharedPtr<T> MakeShared(size_t size, size_t alignment) {
    Layout layout = Layout::Of<T>(size).Align(alignment);
    auto* control_block = ControlBlock::Create(this, layout, size);
    if (control_block == nullptr) {
      return nullptr;
    }
    auto* t = new (control_block->data()) std::remove_extent_t<T>[size];
    return SharedPtr<T>(t, control_block);
  }
 
  // Disallow calls with explicitly-sized array types like `T[kN]`.
  template <typename T,
            int&... kExplicitGuard,
            std::enable_if_t<is_bounded_array_v<T>, int> = 0,
            typename... Args>
  std::enable_if_t<is_bounded_array_v<T>> MakeShared(Args&&...) = delete;
 
  bool Resize(void* ptr, size_t new_size) {
    return ptr != nullptr && new_size != 0 && DoResize(ptr, new_size);
  }
 
  bool Resize(void* ptr, Layout layout, size_t new_size) {
    return ptr != nullptr && new_size != 0 && DoResize(ptr, layout, new_size);
  }
 
  void* Reallocate(void* ptr, Layout new_layout) {
    if (new_layout.size() == 0) {
      return nullptr;
    }
    if (ptr == nullptr) {
      return Allocate(new_layout);
    }
    return DoReallocate(ptr, new_layout);
  }
 
  void* Reallocate(void* ptr, Layout old_layout, size_t new_size) {
    if (new_size == 0) {
      return nullptr;
    }
    if (ptr == nullptr) {
      return Allocate(Layout(new_size, old_layout.alignment()));
    }
    return DoReallocate(ptr, old_layout, new_size);
  }
 
  size_t GetAllocated() const { return DoGetAllocated(); }
 
 protected:
  constexpr Allocator() = default;
 
  explicit constexpr Allocator(const Capabilities& capabilities)
      : Deallocator(capabilities) {}
 
 private:
  virtual void* DoAllocate(Layout layout) = 0;
 
  virtual bool DoResize(void* /*ptr*/, size_t /*new_size*/) { return false; }
 
  virtual bool DoResize(void*, Layout, size_t) { return false; }
 
  virtual void* DoReallocate(void* ptr, Layout new_layout);
 
  virtual void* DoReallocate(void* ptr, Layout old_layout, size_t new_size);
 
  virtual size_t DoGetAllocated() const { return size_t(-1); }
};
 
namespace allocator {
 
// Alias for module consumers using the older name for the above type.
using Allocator = ::pw::Allocator;
 
}  // namespace allocator
}  // namespace pw