Make the fuchsia mojo/public repo the source of truth.

mojo/public/cpp/bindings/lib/bindings_internal.h

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// 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_LIB_BINDINGS_INTERNAL_H_
-#define MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_
-
-#include <type_traits>
-
-#include "mojo/public/cpp/bindings/lib/template_util.h"
-#include "mojo/public/cpp/bindings/struct_ptr.h"
-#include "mojo/public/cpp/system/handle.h"
-#include "mojo/public/cpp/system/message_pipe.h"
-
-namespace mojo {
-class String;
-
-template <typename T>
-class Array;
-
-template <typename Interface>
-class InterfaceHandle;
-
-template <typename Interface>
-class InterfaceRequest;
-
-template <typename K, typename V>
-class Map;
-
-namespace internal {
-template <typename T>
-class Array_Data;
-
-#pragma pack(push, 1)
-
-struct StructHeader {
-  uint32_t num_bytes;
-  uint32_t version;
-};
-static_assert(sizeof(StructHeader) == 8, "Bad sizeof(StructHeader)");
-
-struct ArrayHeader {
-  uint32_t num_bytes;
-  uint32_t num_elements;
-};
-static_assert(sizeof(ArrayHeader) == 8, "Bad_sizeof(ArrayHeader)");
-
-template <typename T>
-union StructPointer {
-  uint64_t offset;
-  T* ptr;
-};
-static_assert(sizeof(StructPointer<char>) == 8, "Bad_sizeof(StructPointer)");
-
-template <typename T>
-union ArrayPointer {
-  uint64_t offset;
-  Array_Data<T>* ptr;
-};
-static_assert(sizeof(ArrayPointer<char>) == 8, "Bad_sizeof(ArrayPointer)");
-
-union StringPointer {
-  uint64_t offset;
-  Array_Data<char>* ptr;
-};
-static_assert(sizeof(StringPointer) == 8, "Bad_sizeof(StringPointer)");
-
-struct Interface_Data {
-  MessagePipeHandle handle;
-  uint32_t version;
-};
-static_assert(sizeof(Interface_Data) == 8, "Bad_sizeof(Interface_Data)");
-
-template <typename T>
-union UnionPointer {
-  uint64_t offset;
-  T* ptr;
-};
-static_assert(sizeof(UnionPointer<char>) == 8, "Bad_sizeof(UnionPointer)");
-
-#pragma pack(pop)
-
-template <typename T>
-void ResetIfNonNull(T* ptr) {
-  if (ptr)
-    *ptr = T();
-}
-
-template <typename T>
-T FetchAndReset(T* ptr) {
-  T temp = *ptr;
-  *ptr = T();
-  return temp;
-}
-
-template <typename H>
-struct IsHandle {
-  enum { value = std::is_base_of<Handle, H>::value };
-};
-
-// TODO(vardhan): Replace RemoveStructPtr<> and UnwrapStructPtr<> with
-// specializations of std::pointer_traits<> on [Inlined]StructPtr<>.
-template <typename T>
-struct RemoveStructPtr {
-  typedef T type;
-};
-
-template <typename T>
-struct RemoveStructPtr<StructPtr<T>> {
-  typedef T type;
-};
-
-template <typename T>
-struct RemoveStructPtr<InlinedStructPtr<T>> {
-  typedef T type;
-};
-
-template <typename T>
-struct UnwrapStructPtr {
-  static T* value(T& x) { return &x; }
-};
-
-template <typename T>
-struct UnwrapStructPtr<StructPtr<T>> {
-  static T* value(StructPtr<T>& x) { return x.get(); }
-};
-
-template <typename T>
-struct UnwrapStructPtr<InlinedStructPtr<T>> {
-  static T* value(InlinedStructPtr<T>& x) { return x.get(); }
-};
-
-template <typename T>
-struct UnwrapConstStructPtr {
-  static const T* value(const T& x) { return &x; }
-};
-
-template <typename T>
-struct UnwrapConstStructPtr<StructPtr<T>> {
-  static const T* value(const StructPtr<T>& x) { return x.get(); }
-};
-
-template <typename T>
-struct UnwrapConstStructPtr<InlinedStructPtr<T>> {
-  static const T* value(const InlinedStructPtr<T>& x) { return x.get(); }
-};
-
-template <typename T>
-struct IsStructPtr {
-  static bool const value = IsSpecializationOf<StructPtr, T>::value ||
-                            IsSpecializationOf<InlinedStructPtr, T>::value;
-};
-
-template <typename T>
-struct IsUnionWrapperType {
-  template <typename U>
-  static YesType Test(const typename U::Data_::MojomUnionDataType*);
-
-  template <typename U>
-  static NoType Test(...);
-
-  static const bool value =
-      sizeof(Test<T>(0)) == sizeof(YesType) && !std::is_const<T>::value;
-};
-
-template <typename T>
-struct IsUnionDataType {
-  template <typename U>
-  static YesType Test(const typename U::MojomUnionDataType*);
-
-  template <typename U>
-  static NoType Test(...);
-
-  static const bool value =
-      sizeof(Test<T>(0)) == sizeof(YesType) && !std::is_const<T>::value;
-};
-
-// To introduce a new mojom type, you must define (partial or full) template
-// specializations for the following traits templates, which operate on the C++
-// wrapper types representing a mojom type:
-//   - WrapperTraits: provides a |DataType| typedef which points to the
-//                    serialized data type.
-//   - ValueTraits: provides an |Equals()| method for comparing the two wrapper
-//                  values of the same type.
-//
-// Currently, full specializations of WrapperTraits are generated for mojo
-// structs in their generated `.mojom.h`. In contrast, WrapperTraits for Unions
-// don't need to be auto-generated because their underlying DataType can be
-// accessed without dependency issues -- a catch-all WrapperTraits for unions is
-// instead defined here.
-// TODO(vardhan): Merge ValueTraits and WrapperTraits into one?
-// TODO(vardhan): Write a doc about all the Traits templates you need to touch
-// when introducing a new mojom type.
-// TODO(vardhan): Instead of providing |move_only| & |is_union| template
-// parameters, provide a default "typename Enable = void" template parameter,
-// and have specializations define their own Enable expressions (similar to how
-// ValueTraits is).
-template <typename T,
-          bool move_only = IsMoveOnlyType<T>::value,
-          bool is_union =
-              IsUnionWrapperType<typename RemoveStructPtr<T>::type>::value>
-struct WrapperTraits;
-
-// Catch-all for all mojom types not specialized below.
-template <typename T>
-struct WrapperTraits<T, false, false> {
-  using DataType = T;
-};
-template <typename H>
-struct WrapperTraits<ScopedHandleBase<H>, true, false> {
-  using DataType = H;
-};
-template <typename I>
-struct WrapperTraits<InterfaceRequest<I>, true, false> {
-  using DataType = MessagePipeHandle;
-};
-template <typename Interface>
-struct WrapperTraits<InterfaceHandle<Interface>, true, false> {
-  using DataType = Interface_Data;
-};
-// Unions.
-template <typename U>
-struct WrapperTraits<StructPtr<U>, true, true> {
-  using DataType = typename U::Data_;
-};
-template <typename U>
-struct WrapperTraits<InlinedStructPtr<U>, true, true> {
-  using DataType = typename U::Data_;
-};
-// Catch-all for other pointer types: arrays, maps.
-template <typename S>
-struct WrapperTraits<S, true, false> {
-  using DataType = typename S::Data_*;
-};
-
-template <typename T, typename Enable = void>
-struct ValueTraits {
-  static bool Equals(const T& a, const T& b) { return a == b; }
-};
-
-template <typename T>
-struct ValueTraits<T,
-                   typename std::enable_if<
-                       IsSpecializationOf<Array, T>::value ||
-                       IsSpecializationOf<Map, T>::value ||
-                       IsSpecializationOf<StructPtr, T>::value ||
-                       IsSpecializationOf<InlinedStructPtr, T>::value>::type> {
-  static bool Equals(const T& a, const T& b) { return a.Equals(b); }
-};
-
-template <typename T>
-struct ValueTraits<ScopedHandleBase<T>> {
-  static bool Equals(const ScopedHandleBase<T>& a,
-                     const ScopedHandleBase<T>& b) {
-    return (&a == &b) || (!a.is_valid() && !b.is_valid());
-  }
-};
-
-// |InterfaceHandle|s hold message pipes uniquely, so they can only be equal if
-// they're the same object or are both "invalid".
-template <typename I>
-struct ValueTraits<InterfaceHandle<I>> {
-  static bool Equals(const InterfaceHandle<I>& a, const InterfaceHandle<I>& b) {
-    return (&a == &b) || (!a.is_valid() && !b.is_valid());
-  }
-};
-
-// |InterfaceRequest|s hold message pipes uniquely, so they can only be equal if
-// they're the same object or are both "invalid".
-template <typename I>
-struct ValueTraits<InterfaceRequest<I>> {
-  static bool Equals(const InterfaceRequest<I>& a,
-                     const InterfaceRequest<I>& b) {
-    return (&a == &b) || (!a.is_pending() && !b.is_pending());
-  }
-};
-
-}  // namespace internal
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_