chromium/mojo/public/cpp/bindings/struct_ptr.h

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MOJO_PUBLIC_CPP_BINDINGS_STRUCT_PTR_H_
#define MOJO_PUBLIC_CPP_BINDINGS_STRUCT_PTR_H_

#include <cstddef>
#include <functional>
#include <memory>
#include <new>

#include "base/check.h"
#include "mojo/public/cpp/bindings/lib/hash_util.h"
#include "mojo/public/cpp/bindings/type_converter.h"
#include "third_party/abseil-cpp/absl/utility/utility.h"
#include "third_party/perfetto/include/perfetto/tracing/traced_value_forward.h"

namespace mojo {
namespace internal {

constexpr size_t kHashSeed = …;

template <typename Struct>
class StructPtrWTFHelper;

template <typename Struct>
class InlinedStructPtrWTFHelper;

}  // namespace internal

// Smart pointer wrapping a mojom structure with move-only semantics.
template <typename S>
class StructPtr { … };

// Designed to be used when Struct is small and copyable.
template <typename S>
class InlinedStructPtr { … };

namespace internal {

template <typename Struct>
class StructPtrWTFHelper { … };

template <typename Struct>
class InlinedStructPtrWTFHelper { … };

// Convenience type trait so that we can get away with defining the comparison
// operators only once.
template <typename T>
struct IsStructPtrImpl : std::false_type { … };

IsStructPtrImpl<StructPtr<S>>;

IsStructPtrImpl<InlinedStructPtr<S>>;

}  // namespace internal

IsStructPtrV;

template <typename Ptr, std::enable_if_t<IsStructPtrV<Ptr>>* = nullptr>
bool operator==(const Ptr& lhs, const Ptr& rhs) { … }

template <typename Ptr, std::enable_if_t<IsStructPtrV<Ptr>>* = nullptr>
bool operator!=(const Ptr& lhs, const Ptr& rhs) { … }

// Perform a deep comparison if possible. Otherwise treat null pointers less
// than valid pointers.
template <typename Ptr, std::enable_if_t<IsStructPtrV<Ptr>>* = nullptr>
bool operator<(const Ptr& lhs, const Ptr& rhs) { … }

template <typename Ptr, std::enable_if_t<IsStructPtrV<Ptr>>* = nullptr>
bool operator<=(const Ptr& lhs, const Ptr& rhs) { … }

template <typename Ptr, std::enable_if_t<IsStructPtrV<Ptr>>* = nullptr>
bool operator>(const Ptr& lhs, const Ptr& rhs) { … }

template <typename Ptr, std::enable_if_t<IsStructPtrV<Ptr>>* = nullptr>
bool operator>=(const Ptr& lhs, const Ptr& rhs) { … }

}  // namespace mojo

namespace std {

hash<mojo::StructPtr<T>>;

hash<mojo::InlinedStructPtr<T>>;

}  // namespace std

#endif  // MOJO_PUBLIC_CPP_BINDINGS_STRUCT_PTR_H_