base::Bind: Implement a 1-arity CancelableCallback and use this to implement

base/cancelable_callback.cc

-// 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.
-
-#include "base/cancelable_callback.h"
-
-#include "base/bind.h"
-#include "base/compiler_specific.h"
-#include "base/logging.h"
-
-namespace base {
-
-CancelableCallback::CancelableCallback()
-    : ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)) {
-}
-
-CancelableCallback::CancelableCallback(const base::Closure& callback)
-    : ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)),
-      callback_(callback) {
-  DCHECK(!callback.is_null());
-  InitializeForwarder();
-}
-
-CancelableCallback::~CancelableCallback() {}
-
-void CancelableCallback::Cancel() {
-  weak_factory_.InvalidateWeakPtrs();
-  callback_.Reset();
-}
-
-bool CancelableCallback::IsCancelled() const {
-  return callback_.is_null();
-}
-
-void CancelableCallback::Reset(const base::Closure& callback) {
-  DCHECK(!callback.is_null());
-
-  // Outstanding tasks (e.g., posted to a message loop) must not be called.
-  Cancel();
-
-  // |forwarder_| is no longer valid after Cancel(), so re-bind.
-  InitializeForwarder();
-
-  callback_ = callback;
-}
-
-const base::Closure& CancelableCallback::callback() const {
-  return forwarder_;
-}
-
-void CancelableCallback::RunCallback() {
-  callback_.Run();
-}
-
-void CancelableCallback::InitializeForwarder() {
-  forwarder_ = base::Bind(&CancelableCallback::RunCallback,
-                          weak_factory_.GetWeakPtr());
-}
-
-}  // namespace bind