15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Copyright (c) 2011 The Chromium Authors. All rights reserved. 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Use of this source code is governed by a BSD-style license that can be 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// found in the LICENSE file. 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This defines a set of argument wrappers and related factory methods that 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// can be used specify the refcounting and reference semantics of arguments 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// that are bound by the Bind() function in base/bind.h. 85821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 95821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// It also defines a set of simple functions and utilities that people want 105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// when using Callback<> and Bind(). 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// ARGUMENT BINDING WRAPPERS 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 155c02ac1a9c1b504631c0a3d2b6e737b5d738bae1Bo Liu// The wrapper functions are base::Unretained(), base::Owned(), base::Passed(), 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// base::ConstRef(), and base::IgnoreResult(). 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Unretained() allows Bind() to bind a non-refcounted class, and to disable 195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// refcounting on arguments that are refcounted objects. 205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Owned() transfers ownership of an object to the Callback resulting from 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// bind; the object will be deleted when the Callback is deleted. 235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Passed() is for transferring movable-but-not-copyable types (eg. scoped_ptr) 255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// through a Callback. Logically, this signifies a destructive transfer of 265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// the state of the argument into the target function. Invoking 275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Callback::Run() twice on a Callback that was created with a Passed() 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// argument will CHECK() because the first invocation would have already 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// transferred ownership to the target function. 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// ConstRef() allows binding a constant reference to an argument rather 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// than a copy. 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// IgnoreResult() is used to adapt a function or Callback with a return type to 355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// one with a void return. This is most useful if you have a function with, 365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// say, a pesky ignorable bool return that you want to use with PostTask or 375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// something else that expect a Callback with a void return. 385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// EXAMPLE OF Unretained(): 405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// class Foo { 425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// public: 435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// void func() { cout << "Foo:f" << endl; } 445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// }; 455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // In some function somewhere. 475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Foo foo; 485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Closure foo_callback = 495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Bind(&Foo::func, Unretained(&foo)); 505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// foo_callback.Run(); // Prints "Foo:f". 515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Without the Unretained() wrapper on |&foo|, the above call would fail 535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// to compile because Foo does not support the AddRef() and Release() methods. 545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// EXAMPLE OF Owned(): 575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// void foo(int* arg) { cout << *arg << endl } 595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// int* pn = new int(1); 615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Closure foo_callback = Bind(&foo, Owned(pn)); 625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// foo_callback.Run(); // Prints "1" 645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// foo_callback.Run(); // Prints "1" 655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// *n = 2; 665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// foo_callback.Run(); // Prints "2" 675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// foo_callback.Reset(); // |pn| is deleted. Also will happen when 695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // |foo_callback| goes out of scope. 705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Without Owned(), someone would have to know to delete |pn| when the last 725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// reference to the Callback is deleted. 735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// EXAMPLE OF ConstRef(): 765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// void foo(int arg) { cout << arg << endl } 785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// int n = 1; 805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Closure no_ref = Bind(&foo, n); 815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Closure has_ref = Bind(&foo, ConstRef(n)); 825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// no_ref.Run(); // Prints "1" 845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// has_ref.Run(); // Prints "1" 855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// n = 2; 875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// no_ref.Run(); // Prints "1" 885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// has_ref.Run(); // Prints "2" 895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Note that because ConstRef() takes a reference on |n|, |n| must outlive all 915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// its bound callbacks. 925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// EXAMPLE OF IgnoreResult(): 955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// int DoSomething(int arg) { cout << arg << endl; } 975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // Assign to a Callback with a void return type. 995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Callback<void(int)> cb = Bind(IgnoreResult(&DoSomething)); 1005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// cb->Run(1); // Prints "1". 1015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // Prints "1" on |ml|. 1035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// ml->PostTask(FROM_HERE, Bind(IgnoreResult(&DoSomething), 1); 1045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// EXAMPLE OF Passed(): 1075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// void TakesOwnership(scoped_ptr<Foo> arg) { } 1095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// scoped_ptr<Foo> CreateFoo() { return scoped_ptr<Foo>(new Foo()); } 1105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// scoped_ptr<Foo> f(new Foo()); 1125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // |cb| is given ownership of Foo(). |f| is now NULL. 1145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // You can use f.Pass() in place of &f, but it's more verbose. 1155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Closure cb = Bind(&TakesOwnership, Passed(&f)); 1165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // Run was never called so |cb| still owns Foo() and deletes 1185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // it on Reset(). 1195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// cb.Reset(); 1205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // |cb| is given a new Foo created by CreateFoo(). 1225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// cb = Bind(&TakesOwnership, Passed(CreateFoo())); 1235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // |arg| in TakesOwnership() is given ownership of Foo(). |cb| 1255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// // no longer owns Foo() and, if reset, would not delete Foo(). 1265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// cb.Run(); // Foo() is now transferred to |arg| and deleted. 1275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// cb.Run(); // This CHECK()s since Foo() already been used once. 1285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Passed() is particularly useful with PostTask() when you are transferring 1305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// ownership of an argument into a task, but don't necessarily know if the 1315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// task will always be executed. This can happen if the task is cancellable 1325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// or if it is posted to a MessageLoopProxy. 1335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// SIMPLE FUNCTIONS AND UTILITIES. 1365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// DoNothing() - Useful for creating a Closure that does nothing when called. 1385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// DeletePointer<T>() - Useful for creating a Closure that will delete a 1395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// pointer when invoked. Only use this when necessary. 1405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// In most cases MessageLoop::DeleteSoon() is a better 1415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// fit. 1425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifndef BASE_BIND_HELPERS_H_ 1445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define BASE_BIND_HELPERS_H_ 1455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "base/basictypes.h" 1475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "base/callback.h" 1485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "base/memory/weak_ptr.h" 1495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "base/template_util.h" 1505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)namespace base { 1525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)namespace internal { 1535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Use the Substitution Failure Is Not An Error (SFINAE) trick to inspect T 1555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// for the existence of AddRef() and Release() functions of the correct 1565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// signature. 1575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// http://en.wikipedia.org/wiki/Substitution_failure_is_not_an_error 1595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// http://stackoverflow.com/questions/257288/is-it-possible-to-write-a-c-template-to-check-for-a-functions-existence 1605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// http://stackoverflow.com/questions/4358584/sfinae-approach-comparison 1615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// http://stackoverflow.com/questions/1966362/sfinae-to-check-for-inherited-member-functions 1625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// The last link in particular show the method used below. 1645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// For SFINAE to work with inherited methods, we need to pull some extra tricks 1665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// with multiple inheritance. In the more standard formulation, the overloads 1675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// of Check would be: 1685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// template <typename C> 1705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Yes NotTheCheckWeWant(Helper<&C::TargetFunc>*); 1715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// template <typename C> 1735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// No NotTheCheckWeWant(...); 1745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// static const bool value = sizeof(NotTheCheckWeWant<T>(0)) == sizeof(Yes); 1765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// The problem here is that template resolution will not match 1785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// C::TargetFunc if TargetFunc does not exist directly in C. That is, if 1795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// TargetFunc in inherited from an ancestor, &C::TargetFunc will not match, 1805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// |value| will be false. This formulation only checks for whether or 1815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// not TargetFunc exist directly in the class being introspected. 1825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// To get around this, we play a dirty trick with multiple inheritance. 1845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// First, We create a class BaseMixin that declares each function that we 1855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// want to probe for. Then we create a class Base that inherits from both T 1865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// (the class we wish to probe) and BaseMixin. Note that the function 1875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// signature in BaseMixin does not need to match the signature of the function 1885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// we are probing for; thus it's easiest to just use void(void). 1895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Now, if TargetFunc exists somewhere in T, then &Base::TargetFunc has an 1915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// ambiguous resolution between BaseMixin and T. This lets us write the 1925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// following: 1935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// template <typename C> 1955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// No GoodCheck(Helper<&C::TargetFunc>*); 1965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// template <typename C> 1985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Yes GoodCheck(...); 1995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// static const bool value = sizeof(GoodCheck<Base>(0)) == sizeof(Yes); 2015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Notice here that the variadic version of GoodCheck() returns Yes here 2035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// instead of No like the previous one. Also notice that we calculate |value| 2045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// by specializing GoodCheck() on Base instead of T. 2055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// We've reversed the roles of the variadic, and Helper overloads. 2075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// GoodCheck(Helper<&C::TargetFunc>*), when C = Base, fails to be a valid 2085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// substitution if T::TargetFunc exists. Thus GoodCheck<Base>(0) will resolve 2095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// to the variadic version if T has TargetFunc. If T::TargetFunc does not 2105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// exist, then &C::TargetFunc is not ambiguous, and the overload resolution 2115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// will prefer GoodCheck(Helper<&C::TargetFunc>*). 2125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This method of SFINAE will correctly probe for inherited names, but it cannot 2145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// typecheck those names. It's still a good enough sanity check though. 2155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Works on gcc-4.2, gcc-4.4, and Visual Studio 2008. 2175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// TODO(ajwong): Move to ref_counted.h or template_util.h when we've vetted 2195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// this works well. 2205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// TODO(ajwong): Make this check for Release() as well. 2225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// See http://crbug.com/82038. 2235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 2245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class SupportsAddRefAndRelease { 2255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef char Yes[1]; 2265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef char No[2]; 2275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) struct BaseMixin { 2295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void AddRef(); 2305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }; 2315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// MSVC warns when you try to use Base if T has a private destructor, the 2335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// common pattern for refcounted types. It does this even though no attempt to 2345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// instantiate Base is made. We disable the warning for this definition. 2355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#if defined(OS_WIN) 236a36e5920737c6adbddd3e43b760e5de8431db6e0Torne (Richard Coles)#pragma warning(push) 2375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#pragma warning(disable:4624) 2385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 2395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) struct Base : public T, public BaseMixin { 2405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }; 2415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#if defined(OS_WIN) 242a36e5920737c6adbddd3e43b760e5de8431db6e0Torne (Richard Coles)#pragma warning(pop) 2435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 2445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) template <void(BaseMixin::*)(void)> struct Helper {}; 2465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) template <typename C> 2485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static No& Check(Helper<&C::AddRef>*); 2495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) template <typename > 2515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static Yes& Check(...); 2525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 2545f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) enum { value = sizeof(Check<Base>(0)) == sizeof(Yes) }; 2555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 2565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Helpers to assert that arguments of a recounted type are bound with a 2585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// scoped_refptr. 2595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <bool IsClasstype, typename T> 2605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnsafeBindtoRefCountedArgHelper : false_type { 2615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 2625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 2645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnsafeBindtoRefCountedArgHelper<true, T> 2655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) : integral_constant<bool, SupportsAddRefAndRelease<T>::value> { 2665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 2675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 2695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnsafeBindtoRefCountedArg : false_type { 2705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 2715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 2735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnsafeBindtoRefCountedArg<T*> 2745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) : UnsafeBindtoRefCountedArgHelper<is_class<T>::value, T> { 2755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 2765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 2785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class HasIsMethodTag { 2795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef char Yes[1]; 2805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef char No[2]; 2815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) template <typename U> 2835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static Yes& Check(typename U::IsMethod*); 2845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) template <typename U> 2865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static No& Check(...); 2875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 2895f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) enum { value = sizeof(Check<T>(0)) == sizeof(Yes) }; 2905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 2915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 2935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class UnretainedWrapper { 2945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 2955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) explicit UnretainedWrapper(T* o) : ptr_(o) {} 2965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) T* get() const { return ptr_; } 2975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) private: 2985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) T* ptr_; 2995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 3025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class ConstRefWrapper { 3035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 3045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) explicit ConstRefWrapper(const T& o) : ptr_(&o) {} 3055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) const T& get() const { return *ptr_; } 3065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) private: 3075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) const T* ptr_; 3085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 3115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct IgnoreResultHelper { 3125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) explicit IgnoreResultHelper(T functor) : functor_(functor) {} 3135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) T functor_; 3155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 3185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct IgnoreResultHelper<Callback<T> > { 3195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) explicit IgnoreResultHelper(const Callback<T>& functor) : functor_(functor) {} 3205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) const Callback<T>& functor_; 3225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// An alternate implementation is to avoid the destructive copy, and instead 3255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// specialize ParamTraits<> for OwnedWrapper<> to change the StorageType to 3265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// a class that is essentially a scoped_ptr<>. 3275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 3285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// The current implementation has the benefit though of leaving ParamTraits<> 3295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// fully in callback_internal.h as well as avoiding type conversions during 3305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// storage. 3315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 3325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class OwnedWrapper { 3335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 3345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) explicit OwnedWrapper(T* o) : ptr_(o) {} 3355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ~OwnedWrapper() { delete ptr_; } 3365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) T* get() const { return ptr_; } 3375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) OwnedWrapper(const OwnedWrapper& other) { 3385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ptr_ = other.ptr_; 3395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) other.ptr_ = NULL; 3405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) private: 3435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) mutable T* ptr_; 3445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// PassedWrapper is a copyable adapter for a scoper that ignores const. 3475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 3485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// It is needed to get around the fact that Bind() takes a const reference to 3495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// all its arguments. Because Bind() takes a const reference to avoid 3505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// unnecessary copies, it is incompatible with movable-but-not-copyable 3515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// types; doing a destructive "move" of the type into Bind() would violate 3525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// the const correctness. 3535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 3545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This conundrum cannot be solved without either C++11 rvalue references or 3555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// a O(2^n) blowup of Bind() templates to handle each combination of regular 3565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// types and movable-but-not-copyable types. Thus we introduce a wrapper type 3575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// that is copyable to transmit the correct type information down into 3585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// BindState<>. Ignoring const in this type makes sense because it is only 3595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// created when we are explicitly trying to do a destructive move. 3605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 3615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Two notes: 3625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 1) PassedWrapper supports any type that has a "Pass()" function. 3635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This is intentional. The whitelisting of which specific types we 3645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// support is maintained by CallbackParamTraits<>. 3655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 2) is_valid_ is distinct from NULL because it is valid to bind a "NULL" 3665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// scoper to a Callback and allow the Callback to execute once. 3675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 3685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class PassedWrapper { 3695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 3705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) explicit PassedWrapper(T scoper) : is_valid_(true), scoper_(scoper.Pass()) {} 3715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PassedWrapper(const PassedWrapper& other) 3725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) : is_valid_(other.is_valid_), scoper_(other.scoper_.Pass()) { 3735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) T Pass() const { 3755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) CHECK(is_valid_); 3765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) is_valid_ = false; 3775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return scoper_.Pass(); 3785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) private: 3815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) mutable bool is_valid_; 3825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) mutable T scoper_; 3835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Unwrap the stored parameters for the wrappers above. 3865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 3875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnwrapTraits { 3885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef const T& ForwardType; 3895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static ForwardType Unwrap(const T& o) { return o; } 3905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 3935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnwrapTraits<UnretainedWrapper<T> > { 3945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef T* ForwardType; 3955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static ForwardType Unwrap(UnretainedWrapper<T> unretained) { 3965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return unretained.get(); 3975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 3995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnwrapTraits<ConstRefWrapper<T> > { 4025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef const T& ForwardType; 4035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static ForwardType Unwrap(ConstRefWrapper<T> const_ref) { 4045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return const_ref.get(); 4055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnwrapTraits<scoped_refptr<T> > { 4105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef T* ForwardType; 4115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static ForwardType Unwrap(const scoped_refptr<T>& o) { return o.get(); } 4125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnwrapTraits<WeakPtr<T> > { 4165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef const WeakPtr<T>& ForwardType; 4175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static ForwardType Unwrap(const WeakPtr<T>& o) { return o; } 4185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnwrapTraits<OwnedWrapper<T> > { 4225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef T* ForwardType; 4235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static ForwardType Unwrap(const OwnedWrapper<T>& o) { 4245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return o.get(); 4255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct UnwrapTraits<PassedWrapper<T> > { 4305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef T ForwardType; 4315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static T Unwrap(PassedWrapper<T>& o) { 4325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return o.Pass(); 4335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Utility for handling different refcounting semantics in the Bind() 4375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// function. 4385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <bool is_method, typename T> 4395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct MaybeRefcount; 4405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct MaybeRefcount<false, T> { 4435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void AddRef(const T&) {} 4445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void Release(const T&) {} 4455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T, size_t n> 4485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct MaybeRefcount<false, T[n]> { 4495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void AddRef(const T*) {} 4505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void Release(const T*) {} 4515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct MaybeRefcount<true, T> { 4555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void AddRef(const T&) {} 4565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void Release(const T&) {} 4575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct MaybeRefcount<true, T*> { 4615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void AddRef(T* o) { o->AddRef(); } 4625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void Release(T* o) { o->Release(); } 4635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// No need to additionally AddRef() and Release() since we are storing a 4665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// scoped_refptr<> inside the storage object already. 4675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct MaybeRefcount<true, scoped_refptr<T> > { 4695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void AddRef(const scoped_refptr<T>& o) {} 4705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void Release(const scoped_refptr<T>& o) {} 4715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct MaybeRefcount<true, const T*> { 4755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void AddRef(const T* o) { o->AddRef(); } 4765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static void Release(const T* o) { o->Release(); } 4775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 4785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// IsWeakMethod is a helper that determine if we are binding a WeakPtr<> to a 4805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// method. It is used internally by Bind() to select the correct 4815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// InvokeHelper that will no-op itself in the event the WeakPtr<> for 4825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// the target object is invalidated. 4835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 4845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// P1 should be the type of the object that will be received of the method. 4855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <bool IsMethod, typename P1> 4865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct IsWeakMethod : public false_type {}; 4875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct IsWeakMethod<true, WeakPtr<T> > : public true_type {}; 4905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct IsWeakMethod<true, ConstRefWrapper<WeakPtr<T> > > : public true_type {}; 4935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} // namespace internal 4955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 4975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline internal::UnretainedWrapper<T> Unretained(T* o) { 4985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return internal::UnretainedWrapper<T>(o); 4995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 5025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline internal::ConstRefWrapper<T> ConstRef(const T& o) { 5035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return internal::ConstRefWrapper<T>(o); 5045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 5075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline internal::OwnedWrapper<T> Owned(T* o) { 5085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return internal::OwnedWrapper<T>(o); 5095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// We offer 2 syntaxes for calling Passed(). The first takes a temporary and 5125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// is best suited for use with the return value of a function. The second 5135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// takes a pointer to the scoper and is just syntactic sugar to avoid having 5145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// to write Passed(scoper.Pass()). 5155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 5165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline internal::PassedWrapper<T> Passed(T scoper) { 5175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return internal::PassedWrapper<T>(scoper.Pass()); 5185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 5205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline internal::PassedWrapper<T> Passed(T* scoper) { 5215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return internal::PassedWrapper<T>(scoper->Pass()); 5225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 5255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline internal::IgnoreResultHelper<T> IgnoreResult(T data) { 5265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return internal::IgnoreResultHelper<T>(data); 5275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <typename T> 5305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline internal::IgnoreResultHelper<Callback<T> > 5315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)IgnoreResult(const Callback<T>& data) { 5325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return internal::IgnoreResultHelper<Callback<T> >(data); 5335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)BASE_EXPORT void DoNothing(); 5365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template<typename T> 5385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void DeletePointer(T* obj) { 5395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) delete obj; 5405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} // namespace base 5435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif // BASE_BIND_HELPERS_H_ 545