mock-allocator.h

// Formatting library for C++ - mock allocator
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.

#ifndef FMT_MOCK_ALLOCATOR_H_
#define FMT_MOCK_ALLOCATOR_H_

#include <assert.h>  // assert
#include <stddef.h>  // size_t

#include <memory>  // std::allocator_traits

#include "gmock/gmock.h"

template <typename T> class mock_allocator {
 public:
  using value_type = T;
  using size_type = size_t;

  using pointer = T*;
  using const_pointer = const T*;
  using reference = T&;
  using const_reference = const T&;
  using difference_type = ptrdiff_t;

  template <typename U> struct rebind {
    using other = mock_allocator<U>;
  };

  mock_allocator() {}
  mock_allocator(const mock_allocator&) {}

  MOCK_METHOD(T*, allocate, (size_t));
  MOCK_METHOD(void, deallocate, (T*, size_t));
};

template <typename Allocator, bool PropagateOnMove = true> class allocator_ref {
 private:
  Allocator* alloc_;

  void move(allocator_ref& other) {
    alloc_ = other.alloc_;
    other.alloc_ = nullptr;
  }

 public:
  using value_type = typename Allocator::value_type;
  using propagate_on_container_move_assignment =
      fmt::bool_constant<PropagateOnMove>;

  explicit allocator_ref(Allocator* alloc = nullptr) : alloc_(alloc) {}

  allocator_ref(const allocator_ref& other) : alloc_(other.alloc_) {}
  allocator_ref(allocator_ref&& other) { move(other); }

  allocator_ref& operator=(allocator_ref&& other) {
    assert(this != &other);
    move(other);
    return *this;
  }

  allocator_ref& operator=(const allocator_ref& other) {
    alloc_ = other.alloc_;
    return *this;
  }

 public:
  auto get() const -> Allocator* { return alloc_; }

  auto allocate(size_t n) -> value_type* {
    return std::allocator_traits<Allocator>::allocate(*alloc_, n);
  }
  void deallocate(value_type* p, size_t n) { alloc_->deallocate(p, n); }

  friend auto operator==(allocator_ref a, allocator_ref b) noexcept -> bool {
    if (a.alloc_ == b.alloc_) return true;
    return a.alloc_ && b.alloc_ && *a.alloc_ == *b.alloc_;
  }

  friend auto operator!=(allocator_ref a, allocator_ref b) noexcept -> bool {
    return !(a == b);
  }
};

#endif  // FMT_MOCK_ALLOCATOR_H_