| Index: base/callback_internal.h
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| diff --git a/base/callback_internal.h b/base/callback_internal.h
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| deleted file mode 100644
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| index fefd7a2b2010ed118ef278cb54a60e1eee132190..0000000000000000000000000000000000000000
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| --- a/base/callback_internal.h
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| +++ /dev/null
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| @@ -1,234 +0,0 @@
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| -// Copyright (c) 2012 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.
|
| -
|
| -// This file contains utility functions and classes that help the
|
| -// implementation, and management of the Callback objects.
|
| -
|
| -#ifndef BASE_CALLBACK_INTERNAL_H_
|
| -#define BASE_CALLBACK_INTERNAL_H_
|
| -
|
| -#include <stddef.h>
|
| -
|
| -#include "base/atomic_ref_count.h"
|
| -#include "base/base_export.h"
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| -#include "base/macros.h"
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| -#include "base/memory/ref_counted.h"
|
| -#include "base/memory/scoped_ptr.h"
|
| -#include "base/template_util.h"
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| -
|
| -template <typename T>
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| -class ScopedVector;
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| -
|
| -namespace base {
|
| -namespace internal {
|
| -class CallbackBase;
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| -
|
| -// BindStateBase is used to provide an opaque handle that the Callback
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| -// class can use to represent a function object with bound arguments. It
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| -// behaves as an existential type that is used by a corresponding
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| -// DoInvoke function to perform the function execution. This allows
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| -// us to shield the Callback class from the types of the bound argument via
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| -// "type erasure."
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| -// At the base level, the only task is to add reference counting data. Don't use
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| -// RefCountedThreadSafe since it requires the destructor to be a virtual method.
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| -// Creating a vtable for every BindState template instantiation results in a lot
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| -// of bloat. Its only task is to call the destructor which can be done with a
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| -// function pointer.
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| -class BindStateBase {
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| - protected:
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| - explicit BindStateBase(void (*destructor)(BindStateBase*))
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| - : ref_count_(0), destructor_(destructor) {}
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| - ~BindStateBase() = default;
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| -
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| - private:
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| - friend class scoped_refptr<BindStateBase>;
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| - friend class CallbackBase;
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| -
|
| - void AddRef();
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| - void Release();
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| -
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| - AtomicRefCount ref_count_;
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| -
|
| - // Pointer to a function that will properly destroy |this|.
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| - void (*destructor_)(BindStateBase*);
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| -
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| - DISALLOW_COPY_AND_ASSIGN(BindStateBase);
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| -};
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| -
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| -// Holds the Callback methods that don't require specialization to reduce
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| -// template bloat.
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| -class BASE_EXPORT CallbackBase {
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| - public:
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| - CallbackBase(const CallbackBase& c);
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| - CallbackBase& operator=(const CallbackBase& c);
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| -
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| - // Returns true if Callback is null (doesn't refer to anything).
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| - bool is_null() const { return bind_state_.get() == NULL; }
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| -
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| - // Returns the Callback into an uninitialized state.
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| - void Reset();
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| -
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| - protected:
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| - // In C++, it is safe to cast function pointers to function pointers of
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| - // another type. It is not okay to use void*. We create a InvokeFuncStorage
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| - // that that can store our function pointer, and then cast it back to
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| - // the original type on usage.
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| - typedef void(*InvokeFuncStorage)(void);
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| -
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| - // Returns true if this callback equals |other|. |other| may be null.
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| - bool Equals(const CallbackBase& other) const;
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| -
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| - // Allow initializing of |bind_state_| via the constructor to avoid default
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| - // initialization of the scoped_refptr. We do not also initialize
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| - // |polymorphic_invoke_| here because doing a normal assignment in the
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| - // derived Callback templates makes for much nicer compiler errors.
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| - explicit CallbackBase(BindStateBase* bind_state);
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| -
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| - // Force the destructor to be instantiated inside this translation unit so
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| - // that our subclasses will not get inlined versions. Avoids more template
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| - // bloat.
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| - ~CallbackBase();
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| -
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| - scoped_refptr<BindStateBase> bind_state_;
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| - InvokeFuncStorage polymorphic_invoke_;
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| -};
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| -
|
| -// A helper template to determine if given type is non-const move-only-type,
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| -// i.e. if a value of the given type should be passed via .Pass() in a
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| -// destructive way.
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| -template <typename T> struct IsMoveOnlyType {
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| - template <typename U>
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| - static YesType Test(const typename U::MoveOnlyTypeForCPP03*);
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| -
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| - template <typename U>
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| - static NoType Test(...);
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| -
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| - static const bool value = sizeof((Test<T>(0))) == sizeof(YesType) &&
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| - !is_const<T>::value;
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| -};
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| -
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| -// Returns |Then| as SelectType::Type if |condition| is true. Otherwise returns
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| -// |Else|.
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| -template <bool condition, typename Then, typename Else>
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| -struct SelectType {
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| - typedef Then Type;
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| -};
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| -
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| -template <typename Then, typename Else>
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| -struct SelectType<false, Then, Else> {
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| - typedef Else Type;
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| -};
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| -
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| -template <typename>
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| -struct CallbackParamTraitsForMoveOnlyType;
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| -
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| -template <typename>
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| -struct CallbackParamTraitsForNonMoveOnlyType;
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| -
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| -// TODO(tzik): Use a default parameter once MSVS supports variadic templates
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| -// with default values.
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| -// http://connect.microsoft.com/VisualStudio/feedbackdetail/view/957801/compilation-error-with-variadic-templates
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| -//
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| -// This is a typetraits object that's used to take an argument type, and
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| -// extract a suitable type for storing and forwarding arguments.
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| -//
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| -// In particular, it strips off references, and converts arrays to
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| -// pointers for storage; and it avoids accidentally trying to create a
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| -// "reference of a reference" if the argument is a reference type.
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| -//
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| -// This array type becomes an issue for storage because we are passing bound
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| -// parameters by const reference. In this case, we end up passing an actual
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| -// array type in the initializer list which C++ does not allow. This will
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| -// break passing of C-string literals.
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| -template <typename T>
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| -struct CallbackParamTraits
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| - : SelectType<IsMoveOnlyType<T>::value,
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| - CallbackParamTraitsForMoveOnlyType<T>,
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| - CallbackParamTraitsForNonMoveOnlyType<T> >::Type {
|
| -};
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| -
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| -template <typename T>
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| -struct CallbackParamTraitsForNonMoveOnlyType {
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| - typedef const T& ForwardType;
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| - typedef T StorageType;
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| -};
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| -
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| -// The Storage should almost be impossible to trigger unless someone manually
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| -// specifies type of the bind parameters. However, in case they do,
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| -// this will guard against us accidentally storing a reference parameter.
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| -//
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| -// The ForwardType should only be used for unbound arguments.
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| -template <typename T>
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| -struct CallbackParamTraitsForNonMoveOnlyType<T&> {
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| - typedef T& ForwardType;
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| - typedef T StorageType;
|
| -};
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| -
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| -// Note that for array types, we implicitly add a const in the conversion. This
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| -// means that it is not possible to bind array arguments to functions that take
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| -// a non-const pointer. Trying to specialize the template based on a "const
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| -// T[n]" does not seem to match correctly, so we are stuck with this
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| -// restriction.
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| -template <typename T, size_t n>
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| -struct CallbackParamTraitsForNonMoveOnlyType<T[n]> {
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| - typedef const T* ForwardType;
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| - typedef const T* StorageType;
|
| -};
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| -
|
| -// See comment for CallbackParamTraits<T[n]>.
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| -template <typename T>
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| -struct CallbackParamTraitsForNonMoveOnlyType<T[]> {
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| - typedef const T* ForwardType;
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| - typedef const T* StorageType;
|
| -};
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| -
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| -// Parameter traits for movable-but-not-copyable scopers.
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| -//
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| -// Callback<>/Bind() understands movable-but-not-copyable semantics where
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| -// the type cannot be copied but can still have its state destructively
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| -// transferred (aka. moved) to another instance of the same type by calling a
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| -// helper function. When used with Bind(), this signifies transferal of the
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| -// object's state to the target function.
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| -//
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| -// For these types, the ForwardType must not be a const reference, or a
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| -// reference. A const reference is inappropriate, and would break const
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| -// correctness, because we are implementing a destructive move. A non-const
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| -// reference cannot be used with temporaries which means the result of a
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| -// function or a cast would not be usable with Callback<> or Bind().
|
| -template <typename T>
|
| -struct CallbackParamTraitsForMoveOnlyType {
|
| - typedef T ForwardType;
|
| - typedef T StorageType;
|
| -};
|
| -
|
| -// CallbackForward() is a very limited simulation of C++11's std::forward()
|
| -// used by the Callback/Bind system for a set of movable-but-not-copyable
|
| -// types. It is needed because forwarding a movable-but-not-copyable
|
| -// argument to another function requires us to invoke the proper move
|
| -// operator to create a rvalue version of the type. The supported types are
|
| -// whitelisted below as overloads of the CallbackForward() function. The
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| -// default template compiles out to be a no-op.
|
| -//
|
| -// In C++11, std::forward would replace all uses of this function. However, it
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| -// is impossible to implement a general std::forward with C++11 due to a lack
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| -// of rvalue references.
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| -//
|
| -// In addition to Callback/Bind, this is used by PostTaskAndReplyWithResult to
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| -// simulate std::forward() and forward the result of one Callback as a
|
| -// parameter to another callback. This is to support Callbacks that return
|
| -// the movable-but-not-copyable types whitelisted above.
|
| -template <typename T>
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| -typename enable_if<!IsMoveOnlyType<T>::value, T>::type& CallbackForward(T& t) {
|
| - return t;
|
| -}
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| -
|
| -template <typename T>
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| -typename enable_if<IsMoveOnlyType<T>::value, T>::type CallbackForward(T& t) {
|
| - return t.Pass();
|
| -}
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| -
|
| -} // namespace internal
|
| -} // namespace base
|
| -
|
| -#endif // BASE_CALLBACK_INTERNAL_H_
|
|
|