Add a CallbackRegistry class to base/ to manage callbacks

base/callback_list.h

Index: base/callback_list.h
diff --git a/base/callback_list.h b/base/callback_list.h
new file mode 100644
index 0000000000000000000000000000000000000000..aae10252d98a39ca4c8168813901fbd53b116c22
--- /dev/null
+++ b/base/callback_list.h
@@ -0,0 +1,114 @@
+// 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 BASE_CALLBACK_LIST_H_
+#define BASE_CALLBACK_LIST_H_
+
+#include <algorithm>
+#include <limits>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/callback_list_internal.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+
+// OVERVIEW:
+//
+// A container for a list of callbacks.  Unlike a normal STL vector or list,
+// this container can be modified during iteration without invalidating the
+// iterator. It safely handles the case of a callback removing itself
+// or another callback from the list while callbacks are being run.
+//
+// TYPICAL USAGE:
+//
+// class MyWidget {
+//  public:
+//   ...
+//
+//   typedef base::Callback<void(const Foo&)> OnFooCallback;
+//
+//   base::Closure RegisterCallback(const OnFooCallback& cb) {
+//     return callback_list_.Add(cb);
+//   }
+//
+//  private:
+//   void NotifyFoo(const Foo& foo) {
+//      callback_list_.Run(foo);
+//   }
+//
+//   CallbackList<Foo> callback_list_(CallbackList<Foo>::NOTIFY_ALL);
+// };
+//
+//
+// class MyWidgetListener {
+//  public:
+//   MyWidgetListener::MyWidgetListener() {
+//     remove_foo_callback_.Reset(
+//         MyWidget::GetCurrent()->RegisterCallback(
+//             base::Bind(&MyWidgetListener::OnFoo, this)));
+//   }
+//
+//   MyWidgetListener::~MyWidgetListener() {
+//      // ScopedClosureRunner runs its closure automatically on deletion.
+//   }
+//
+//   void OnFoo(const Foo& foo) {
+//     // Do something.
+//   }
+//
+//  private:
+//   base::ScopedClosureRunner remove_foo_callback_;
+// };
+
+namespace base {
+
+template <typename Details>
+class CallbackList
+    : public base::internal::CallbackListBase<Callback<void(const Details&)> > {
+ public:
+  typedef base::Callback<void(const Details&)> CallbackType;
+
+  CallbackList() {}
+
+  // Execute all active callbacks with |details| parameter.
+  void Run(const Details& details) {
+    internal::CallbackListImpl::Iterator it = this->GetIterator();
+    CallbackType* cb;
+    // static_cast is safe here. All callbacks were added via
+    // CallbackListBase::Add() and so must be of type
+    // Callback<void(const Details&)>.
+    while((cb = static_cast<CallbackType*>(it.GetNext())) != NULL) {
+      cb->Run(details);
+    }
+  }
+
+private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackList);
+};
+
+template <> class CallbackList<void>
+    : public base::internal::CallbackListBase<Closure> {
+ public:
+  CallbackList() {}
+
+  // Execute all active callbacks.
+  void Run() {
+    internal::CallbackListImpl::Iterator it = this->GetIterator();
+    Closure* cb;
+    // static_cast is safe here. All callbacks were added via
+    // CallbackListBase::Add() and so must be Closures.
+    while((cb = static_cast<Closure*>(it.GetNext())) != NULL) {
+      cb->Run();
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackList);
+};
+
+}  // namespace base
+
+#endif  // BASE_CALLBACK_LIST_H_