Move //mojo/{public, edk} underneath //third_party

mojo/edk/system/memory.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_EDK_SYSTEM_MEMORY_H_
-#define MOJO_EDK_SYSTEM_MEMORY_H_
-
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>  // For |memcpy()|.
-
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "mojo/edk/system/system_impl_export.h"
-#include "mojo/public/c/system/macros.h"
-
-namespace mojo {
-namespace system {
-
-namespace internal {
-
-// Removes |const| from |T| (available as |remove_const<T>::type|):
-// TODO(vtl): Remove these once we have the C++11 |remove_const|.
-template <typename T>
-struct remove_const {
-  typedef T type;
-};
-template <typename T>
-struct remove_const<const T> {
-  typedef T type;
-};
-
-// Yields |(const) char| if |T| is |(const) void|, else |T|:
-template <typename T>
-struct VoidToChar {
-  typedef T type;
-};
-template <>
-struct VoidToChar<void> {
-  typedef char type;
-};
-template <>
-struct VoidToChar<const void> {
-  typedef const char type;
-};
-
-// Checks (insofar as appropriate/possible) that |pointer| is a valid pointer to
-// a buffer of the given size and alignment (both in bytes).
-template <size_t size, size_t alignment>
-void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer(const void* pointer);
-
-// Checks (insofar as appropriate/possible) that |pointer| is a valid pointer to
-// a buffer of |count| elements of the given size and alignment (both in bytes).
-template <size_t size, size_t alignment>
-void MOJO_SYSTEM_IMPL_EXPORT
-CheckUserPointerWithCount(const void* pointer, size_t count);
-
-// Checks (insofar as appropriate/possible) that |pointer| is a valid pointer to
-// a buffer of the given size and alignment (both in bytes).
-template <size_t alignment>
-void MOJO_SYSTEM_IMPL_EXPORT
-CheckUserPointerWithSize(const void* pointer, size_t size);
-
-}  // namespace internal
-
-// Forward declarations so that they can be friended.
-template <typename Type>
-class UserPointerReader;
-template <typename Type>
-class UserPointerWriter;
-template <typename Type>
-class UserPointerReaderWriter;
-template <class Options>
-class UserOptionsReader;
-
-// Provides a convenient way to implicitly get null |UserPointer<Type>|s.
-struct NullUserPointer {};
-
-// Represents a user pointer to a single |Type| (which must be POD), for Mojo
-// primitive parameters.
-//
-// Use a const |Type| for in parameters, and non-const |Type|s for out and
-// in-out parameters (in which case the |Put()| method is available).
-template <typename Type>
-class UserPointer {
- private:
-  typedef typename internal::VoidToChar<Type>::type NonVoidType;
-
- public:
-  // Instead of explicitly using these constructors, you can often use
-  // |MakeUserPointer()| (or |NullUserPointer()| for null pointers). (The common
-  // exception is when you have, e.g., a |char*| and want to get a
-  // |UserPointer<void>|.)
-  UserPointer() : pointer_(nullptr) {}
-  explicit UserPointer(Type* pointer) : pointer_(pointer) {}
-  // Allow implicit conversion from the "null user pointer".
-  UserPointer(NullUserPointer) : pointer_(nullptr) {}
-  ~UserPointer() {}
-
-  // Allow assignment from the "null user pointer".
-  UserPointer<Type>& operator=(NullUserPointer) {
-    pointer_ = nullptr;
-    return *this;
-  }
-
-  // Allow conversion to a "non-const" |UserPointer|.
-  operator UserPointer<const Type>() const {
-    return UserPointer<const Type>(pointer_);
-  }
-
-  bool IsNull() const { return !pointer_; }
-
-  // "Reinterpret casts" to a |UserPointer<ToType>|.
-  template <typename ToType>
-  UserPointer<ToType> ReinterpretCast() const {
-    return UserPointer<ToType>(reinterpret_cast<ToType*>(pointer_));
-  }
-
-  // Checks that this pointer points to a valid |Type| in the same way as
-  // |Get()| and |Put()|.
-  // TODO(vtl): Logically, there should be separate read checks and write
-  // checks.
-  void Check() const {
-    internal::CheckUserPointer<sizeof(NonVoidType), MOJO_ALIGNOF(NonVoidType)>(
-        pointer_);
-  }
-
-  // Checks that this pointer points to a valid array (of type |Type|, or just a
-  // buffer if |Type| is |void| or |const void|) of |count| elements (or bytes
-  // if |Type| is |void| or |const void|) in the same way as |GetArray()| and
-  // |PutArray()|.
-  // TODO(vtl): Logically, there should be separate read checks and write
-  // checks.
-  // TODO(vtl): Switch more things to use this.
-  void CheckArray(size_t count) const {
-    internal::CheckUserPointerWithCount<sizeof(NonVoidType),
-                                        MOJO_ALIGNOF(NonVoidType)>(pointer_,
-                                                                   count);
-  }
-
-  // Gets the value (of type |Type|, or a |char| if |Type| is |void|) pointed to
-  // by this user pointer. Use this when you'd use the rvalue |*user_pointer|,
-  // but be aware that this may be costly -- so if the value will be used
-  // multiple times, you should save it.
-  //
-  // (We want to force a copy here, so return |Type| not |const Type&|.)
-  NonVoidType Get() const {
-    Check();
-    internal::CheckUserPointer<sizeof(NonVoidType), MOJO_ALIGNOF(NonVoidType)>(
-        pointer_);
-    return *pointer_;
-  }
-
-  // Gets an array (of type |Type|, or just a buffer if |Type| is |void| or
-  // |const void|) of |count| elements (or bytes if |Type| is |void| or |const
-  // void|) from the location pointed to by this user pointer. Use this when
-  // you'd do something like |memcpy(destination, user_pointer, count *
-  // sizeof(Type)|.
-  void GetArray(typename internal::remove_const<Type>::type* destination,
-                size_t count) const {
-    CheckArray(count);
-    memcpy(destination, pointer_, count * sizeof(NonVoidType));
-  }
-
-  // Puts a value (of type |Type|, or of type |char| if |Type| is |void|) to the
-  // location pointed to by this user pointer. Use this when you'd use the
-  // lvalue |*user_pointer|. Since this may be costly, you should avoid using
-  // this (for the same user pointer) more than once.
-  //
-  // Note: This |Put()| method is not valid when |T| is const, e.g., |const
-  // uint32_t|, but it's okay to include them so long as this template is only
-  // implicitly instantiated (see 14.7.1 of the C++11 standard) and not
-  // explicitly instantiated. (On implicit instantiation, only the declarations
-  // need be valid, not the definitions.)
-  //
-  // In C++11, we could do something like:
-  //   template <typename _Type = Type>
-  //   typename enable_if<!is_const<_Type>::value &&
-  //                      !is_void<_Type>::value>::type Put(
-  //       const _Type& value) { ... }
-  // (which obviously be correct), but C++03 doesn't allow default function
-  // template arguments.
-  void Put(const NonVoidType& value) {
-    Check();
-    *pointer_ = value;
-  }
-
-  // Puts an array (of type |Type|, or just a buffer if |Type| is |void|) with
-  // |count| elements (or bytes |Type| is |void|) to the location pointed to by
-  // this user pointer. Use this when you'd do something like
-  // |memcpy(user_pointer, source, count * sizeof(Type))|.
-  //
-  // Note: The same comments about the validity of |Put()| (except for the part
-  // about |void|) apply here.
-  void PutArray(const Type* source, size_t count) {
-    CheckArray(count);
-    memcpy(pointer_, source, count * sizeof(NonVoidType));
-  }
-
-  // Gets a |UserPointer| at offset |i| (in |Type|s) relative to this.
-  UserPointer At(size_t i) const {
-    return UserPointer(
-        static_cast<Type*>(static_cast<NonVoidType*>(pointer_) + i));
-  }
-
-  // Gets the value of the |UserPointer| as a |uintptr_t|. This should not be
-  // casted back to a pointer (and dereferenced), but may be used as a key for
-  // lookup or passed back to the user.
-  uintptr_t GetPointerValue() const {
-    return reinterpret_cast<uintptr_t>(pointer_);
-  }
-
-  // These provides safe (read-only/write-only/read-and-write) access to a
-  // |UserPointer<Type>| (probably pointing to an array) using just an ordinary
-  // pointer (obtained via |GetPointer()|).
-  //
-  // The memory returned by |GetPointer()| may be a copy of the original user
-  // memory, but should be modified only if the user is intended to eventually
-  // see the change.) If any changes are made, |Commit()| should be called to
-  // guarantee that the changes are written back to user memory (it may be
-  // called multiple times).
-  //
-  // Note: These classes are designed to allow fast, unsafe implementations (in
-  // which |GetPointer()| just returns the user pointer) if desired. Thus if
-  // |Commit()| is *not* called, changes may or may not be made visible to the
-  // user.
-  //
-  // Use these classes in the following way:
-  //
-  //   MojoResult Core::PutFoos(UserPointer<const uint32_t> foos,
-  //                            uint32_t num_foos) {
-  //     UserPointer<const uint32_t>::Reader foos_reader(foos, num_foos);
-  //     return PutFoosImpl(foos_reader.GetPointer(), num_foos);
-  //   }
-  //
-  //   MojoResult Core::GetFoos(UserPointer<uint32_t> foos,
-  //                            uint32_t num_foos) {
-  //     UserPointer<uint32_t>::Writer foos_writer(foos, num_foos);
-  //     MojoResult rv = GetFoosImpl(foos.GetPointer(), num_foos);
-  //     foos_writer.Commit();
-  //     return rv;
-  //   }
-  //
-  // TODO(vtl): Possibly, since we're not really being safe, we should just not
-  // copy for Release builds.
-  typedef UserPointerReader<Type> Reader;
-  typedef UserPointerWriter<Type> Writer;
-  typedef UserPointerReaderWriter<Type> ReaderWriter;
-
- private:
-  friend class UserPointerReader<Type>;
-  friend class UserPointerReader<const Type>;
-  friend class UserPointerWriter<Type>;
-  friend class UserPointerReaderWriter<Type>;
-  template <class Options>
-  friend class UserOptionsReader;
-
-  Type* pointer_;
-  // Allow copy and assignment.
-};
-
-// Provides a convenient way to make a |UserPointer<Type>|.
-template <typename Type>
-inline UserPointer<Type> MakeUserPointer(Type* pointer) {
-  return UserPointer<Type>(pointer);
-}
-
-// Implementation of |UserPointer<Type>::Reader|.
-template <typename Type>
-class UserPointerReader {
- private:
-  typedef typename internal::remove_const<Type>::type TypeNoConst;
-
- public:
-  // Note: If |count| is zero, |GetPointer()| will always return null.
-  UserPointerReader(UserPointer<const Type> user_pointer, size_t count) {
-    Init(user_pointer.pointer_, count, true);
-  }
-  UserPointerReader(UserPointer<TypeNoConst> user_pointer, size_t count) {
-    Init(user_pointer.pointer_, count, true);
-  }
-
-  const Type* GetPointer() const { return buffer_.get(); }
-
- private:
-  template <class Options>
-  friend class UserOptionsReader;
-
-  struct NoCheck {};
-  UserPointerReader(NoCheck,
-                    UserPointer<const Type> user_pointer,
-                    size_t count) {
-    Init(user_pointer.pointer_, count, false);
-  }
-
-  void Init(const Type* user_pointer, size_t count, bool check) {
-    if (count == 0)
-      return;
-
-    if (check) {
-      internal::CheckUserPointerWithCount<sizeof(Type), MOJO_ALIGNOF(Type)>(
-          user_pointer, count);
-    }
-    buffer_.reset(new TypeNoConst[count]);
-    memcpy(buffer_.get(), user_pointer, count * sizeof(Type));
-  }
-
-  scoped_ptr<TypeNoConst[]> buffer_;
-
-  DISALLOW_COPY_AND_ASSIGN(UserPointerReader);
-};
-
-// Implementation of |UserPointer<Type>::Writer|.
-template <typename Type>
-class UserPointerWriter {
- public:
-  // Note: If |count| is zero, |GetPointer()| will always return null.
-  UserPointerWriter(UserPointer<Type> user_pointer, size_t count)
-      : user_pointer_(user_pointer), count_(count) {
-    if (count_ > 0) {
-      buffer_.reset(new Type[count_]);
-      memset(buffer_.get(), 0, count_ * sizeof(Type));
-    }
-  }
-
-  Type* GetPointer() const { return buffer_.get(); }
-
-  void Commit() {
-    internal::CheckUserPointerWithCount<sizeof(Type), MOJO_ALIGNOF(Type)>(
-        user_pointer_.pointer_, count_);
-    memcpy(user_pointer_.pointer_, buffer_.get(), count_ * sizeof(Type));
-  }
-
- private:
-  UserPointer<Type> user_pointer_;
-  size_t count_;
-  scoped_ptr<Type[]> buffer_;
-
-  DISALLOW_COPY_AND_ASSIGN(UserPointerWriter);
-};
-
-// Implementation of |UserPointer<Type>::ReaderWriter|.
-template <typename Type>
-class UserPointerReaderWriter {
- public:
-  // Note: If |count| is zero, |GetPointer()| will always return null.
-  UserPointerReaderWriter(UserPointer<Type> user_pointer, size_t count)
-      : user_pointer_(user_pointer), count_(count) {
-    if (count_ > 0) {
-      internal::CheckUserPointerWithCount<sizeof(Type), MOJO_ALIGNOF(Type)>(
-          user_pointer_.pointer_, count_);
-      buffer_.reset(new Type[count]);
-      memcpy(buffer_.get(), user_pointer.pointer_, count * sizeof(Type));
-    }
-  }
-
-  Type* GetPointer() const { return buffer_.get(); }
-  size_t GetCount() const { return count_; }
-
-  void Commit() {
-    internal::CheckUserPointerWithCount<sizeof(Type), MOJO_ALIGNOF(Type)>(
-        user_pointer_.pointer_, count_);
-    memcpy(user_pointer_.pointer_, buffer_.get(), count_ * sizeof(Type));
-  }
-
- private:
-  UserPointer<Type> user_pointer_;
-  size_t count_;
-  scoped_ptr<Type[]> buffer_;
-
-  DISALLOW_COPY_AND_ASSIGN(UserPointerReaderWriter);
-};
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // MOJO_EDK_SYSTEM_MEMORY_H_