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// Copyright (c) 2011 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 BASE_CALLBACK_OLD_H_
#define BASE_CALLBACK_OLD_H_
#pragma once
#include "base/memory/raw_scoped_refptr_mismatch_checker.h"
#include "base/tuple.h"
// Callback --------------------------------------------------------------------
//
// A Callback is like a Task but with unbound parameters. It is basically an
// object-oriented function pointer.
//
// Callbacks are designed to work with Tuples. A set of helper functions and
// classes is provided to hide the Tuple details from the consumer. Client
// code will generally work with the CallbackRunner base class, which merely
// provides a Run method and is returned by the New* functions. This allows
// users to not care which type of class implements the callback, only that it
// has a certain number and type of arguments.
//
// The implementation of this is done by CallbackImpl, which inherits
// CallbackStorage to store the data. This allows the storage of the data
// (requiring the class type T) to be hidden from users, who will want to call
// this regardless of the implementor's type T.
//
// Note that callbacks currently have no facility for cancelling or abandoning
// them. We currently handle this at a higher level for cases where this is
// necessary. The pointer in a callback must remain valid until the callback
// is made.
//
// Like Task, the callback executor is responsible for deleting the callback
// pointer once the callback has executed.
//
// Example client usage:
// void Object::DoStuff(int, string);
// Callback2<int, string>::Type* callback =
// NewCallback(obj, &Object::DoStuff);
// callback->Run(5, string("hello"));
// delete callback;
// or, equivalently, using tuples directly:
// CallbackRunner<Tuple2<int, string> >* callback =
// NewCallback(obj, &Object::DoStuff);
// callback->RunWithParams(MakeTuple(5, string("hello")));
//
// There is also a 0-args version that returns a value. Example:
// int Object::GetNextInt();
// CallbackWithReturnValue<int>::Type* callback =
// NewCallbackWithReturnValue(obj, &Object::GetNextInt);
// int next_int = callback->Run();
// delete callback;
// Base for all Callbacks that handles storage of the pointers.
template <class T, typename Method>
class CallbackStorage {
public:
CallbackStorage(T* obj, Method meth) : obj_(obj), meth_(meth) {
}
protected:
T* obj_;
Method meth_;
};
// Interface that is exposed to the consumer, that does the actual calling
// of the method.
template <typename Params>
class CallbackRunner {
public:
typedef Params TupleType;
virtual ~CallbackRunner() {}
virtual void RunWithParams(const Params& params) = 0;
// Convenience functions so callers don't have to deal with Tuples.
inline void Run() {
RunWithParams(Tuple0());
}
template <typename Arg1>
inline void Run(const Arg1& a) {
RunWithParams(Params(a));
}
template <typename Arg1, typename Arg2>
inline void Run(const Arg1& a, const Arg2& b) {
RunWithParams(Params(a, b));
}
template <typename Arg1, typename Arg2, typename Arg3>
inline void Run(const Arg1& a, const Arg2& b, const Arg3& c) {
RunWithParams(Params(a, b, c));
}
template <typename Arg1, typename Arg2, typename Arg3, typename Arg4>
inline void Run(const Arg1& a, const Arg2& b, const Arg3& c, const Arg4& d) {
RunWithParams(Params(a, b, c, d));
}
template <typename Arg1, typename Arg2, typename Arg3,
typename Arg4, typename Arg5>
inline void Run(const Arg1& a, const Arg2& b, const Arg3& c,
const Arg4& d, const Arg5& e) {
RunWithParams(Params(a, b, c, d, e));
}
};
template <class T, typename Method, typename Params>
class CallbackImpl : public CallbackStorage<T, Method>,
public CallbackRunner<Params> {
public:
CallbackImpl(T* obj, Method meth) : CallbackStorage<T, Method>(obj, meth) {
}
virtual void RunWithParams(const Params& params) {
// use "this->" to force C++ to look inside our templatized base class; see
// Effective C++, 3rd Ed, item 43, p210 for details.
DispatchToMethod(this->obj_, this->meth_, params);
}
};
// 0-arg implementation
struct Callback0 {
typedef CallbackRunner<Tuple0> Type;
};
template <class T>
typename Callback0::Type* NewCallback(T* object, void (T::*method)()) {
return new CallbackImpl<T, void (T::*)(), Tuple0 >(object, method);
}
// 1-arg implementation
template <typename Arg1>
struct Callback1 {
typedef CallbackRunner<Tuple1<Arg1> > Type;
};
template <class T, typename Arg1>
typename Callback1<Arg1>::Type* NewCallback(T* object,
void (T::*method)(Arg1)) {
return new CallbackImpl<T, void (T::*)(Arg1), Tuple1<Arg1> >(object, method);
}
// 2-arg implementation
template <typename Arg1, typename Arg2>
struct Callback2 {
typedef CallbackRunner<Tuple2<Arg1, Arg2> > Type;
};
template <class T, typename Arg1, typename Arg2>
typename Callback2<Arg1, Arg2>::Type* NewCallback(
T* object,
void (T::*method)(Arg1, Arg2)) {
return new CallbackImpl<T, void (T::*)(Arg1, Arg2),
Tuple2<Arg1, Arg2> >(object, method);
}
// 3-arg implementation
template <typename Arg1, typename Arg2, typename Arg3>
struct Callback3 {
typedef CallbackRunner<Tuple3<Arg1, Arg2, Arg3> > Type;
};
template <class T, typename Arg1, typename Arg2, typename Arg3>
typename Callback3<Arg1, Arg2, Arg3>::Type* NewCallback(
T* object,
void (T::*method)(Arg1, Arg2, Arg3)) {
return new CallbackImpl<T, void (T::*)(Arg1, Arg2, Arg3),
Tuple3<Arg1, Arg2, Arg3> >(object, method);
}
// 4-arg implementation
template <typename Arg1, typename Arg2, typename Arg3, typename Arg4>
struct Callback4 {
typedef CallbackRunner<Tuple4<Arg1, Arg2, Arg3, Arg4> > Type;
};
template <class T, typename Arg1, typename Arg2, typename Arg3, typename Arg4>
typename Callback4<Arg1, Arg2, Arg3, Arg4>::Type* NewCallback(
T* object,
void (T::*method)(Arg1, Arg2, Arg3, Arg4)) {
return new CallbackImpl<T, void (T::*)(Arg1, Arg2, Arg3, Arg4),
Tuple4<Arg1, Arg2, Arg3, Arg4> >(object, method);
}
// 5-arg implementation
template <typename Arg1, typename Arg2, typename Arg3,
typename Arg4, typename Arg5>
struct Callback5 {
typedef CallbackRunner<Tuple5<Arg1, Arg2, Arg3, Arg4, Arg5> > Type;
};
template <class T, typename Arg1, typename Arg2,
typename Arg3, typename Arg4, typename Arg5>
typename Callback5<Arg1, Arg2, Arg3, Arg4, Arg5>::Type* NewCallback(
T* object,
void (T::*method)(Arg1, Arg2, Arg3, Arg4, Arg5)) {
return new CallbackImpl<T, void (T::*)(Arg1, Arg2, Arg3, Arg4, Arg5),
Tuple5<Arg1, Arg2, Arg3, Arg4, Arg5> >(object, method);
}
// An UnboundMethod is a wrapper for a method where the actual object is
// provided at Run dispatch time.
template <class T, class Method, class Params>
class UnboundMethod {
public:
UnboundMethod(Method m, const Params& p) : m_(m), p_(p) {
COMPILE_ASSERT(
(base::internal::ParamsUseScopedRefptrCorrectly<Params>::value),
badunboundmethodparams);
}
void Run(T* obj) const {
DispatchToMethod(obj, m_, p_);
}
private:
Method m_;
Params p_;
};
// Return value implementation with no args.
template <typename ReturnValue>
struct CallbackWithReturnValue {
class Type {
public:
virtual ~Type() {}
virtual ReturnValue Run() = 0;
};
};
template <class T, typename Method, typename ReturnValue>
class CallbackWithReturnValueImpl
: public CallbackStorage<T, Method>,
public CallbackWithReturnValue<ReturnValue>::Type {
public:
CallbackWithReturnValueImpl(T* obj, Method meth)
: CallbackStorage<T, Method>(obj, meth) {}
virtual ReturnValue Run() {
return (this->obj_->*(this->meth_))();
}
protected:
virtual ~CallbackWithReturnValueImpl() {}
};
template <class T, typename ReturnValue>
typename CallbackWithReturnValue<ReturnValue>::Type*
NewCallbackWithReturnValue(T* object, ReturnValue (T::*method)()) {
return new CallbackWithReturnValueImpl<T, ReturnValue (T::*)(), ReturnValue>(
object, method);
}
#endif // BASE_CALLBACK_OLD_H_