Revert of [Base] Use variadic template in callback_list.h (wave 1)

base/callback_list.h.pump

+$$ This is a pump file for generating file templates.  Pump is a python
+$$ script that is part of the Google Test suite of utilities.  Description
+$$ can be found here:
+$$
+$$ http://code.google.com/p/googletest/wiki/PumpManual
+$$
+
+$$ See comment for MAX_ARITY in base/bind.h.pump.
+$var MAX_ARITY = 7
+
+// 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 <list>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/callback_internal.h"
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "base/memory/scoped_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;
+//
+//   scoped_ptr<base::CallbackList<void(const Foo&)>::Subscription>
+//   RegisterCallback(const OnFooCallback& cb) {
+//     return callback_list_.Add(cb);
+//   }
+//
+//  private:
+//   void NotifyFoo(const Foo& foo) {
+//      callback_list_.Notify(foo);
+//   }
+//
+//   base::CallbackList<void(const Foo&)> callback_list_;
+//
+//   DISALLOW_COPY_AND_ASSIGN(MyWidget);
+// };
+//
+//
+// class MyWidgetListener {
+//  public:
+//   MyWidgetListener::MyWidgetListener() {
+//     foo_subscription_ = MyWidget::GetCurrent()->RegisterCallback(
+//             base::Bind(&MyWidgetListener::OnFoo, this)));
+//   }
+//
+//   MyWidgetListener::~MyWidgetListener() {
+//      // Subscription gets deleted automatically and will deregister
+//      // the callback in the process.
+//   }
+//
+//  private:
+//   void OnFoo(const Foo& foo) {
+//     // Do something.
+//   }
+//
+//   scoped_ptr<base::CallbackList<void(const Foo&)>::Subscription>
+//       foo_subscription_;
+//
+//   DISALLOW_COPY_AND_ASSIGN(MyWidgetListener);
+// };
+
+namespace base {
+
+namespace internal {
+
+template <typename CallbackType>
+class CallbackListBase {
+ public:
+  class Subscription {
+   public:
+    Subscription(CallbackListBase<CallbackType>* list,
+                 typename std::list<CallbackType>::iterator iter)
+        : list_(list),
+          iter_(iter) {
+    }
+
+    ~Subscription() {
+      if (list_->active_iterator_count_) {
+        iter_->Reset();
+      } else {
+        list_->callbacks_.erase(iter_);
+        if (!list_->removal_callback_.is_null())
+          list_->removal_callback_.Run();
+      }
+    }
+
+   private:
+    CallbackListBase<CallbackType>* list_;
+    typename std::list<CallbackType>::iterator iter_;
+
+    DISALLOW_COPY_AND_ASSIGN(Subscription);
+  };
+
+  // Add a callback to the list. The callback will remain registered until the
+  // returned Subscription is destroyed, which must occur before the
+  // CallbackList is destroyed.
+  scoped_ptr<Subscription> Add(const CallbackType& cb) WARN_UNUSED_RESULT {
+    DCHECK(!cb.is_null());
+    return scoped_ptr<Subscription>(
+        new Subscription(this, callbacks_.insert(callbacks_.end(), cb)));
+  }
+
+  // Sets a callback which will be run when a subscription list is changed.
+  void set_removal_callback(const Closure& callback) {
+    removal_callback_ = callback;
+  }
+
+  // Returns true if there are no subscriptions. This is only valid to call when
+  // not looping through the list.
+  bool empty() {
+    DCHECK_EQ(0, active_iterator_count_);
+    return callbacks_.empty();
+  }
+
+ protected:
+  // An iterator class that can be used to access the list of callbacks.
+  class Iterator {
+   public:
+    explicit Iterator(CallbackListBase<CallbackType>* list)
+        : list_(list),
+          list_iter_(list_->callbacks_.begin()) {
+      ++list_->active_iterator_count_;
+    }
+
+    Iterator(const Iterator& iter)
+        : list_(iter.list_),
+          list_iter_(iter.list_iter_) {
+      ++list_->active_iterator_count_;
+    }
+
+    ~Iterator() {
+      if (list_ && --list_->active_iterator_count_ == 0) {
+        list_->Compact();
+      }
+    }
+
+    CallbackType* GetNext() {
+      while ((list_iter_ != list_->callbacks_.end()) && list_iter_->is_null())
+        ++list_iter_;
+
+      CallbackType* cb = NULL;
+      if (list_iter_ != list_->callbacks_.end()) {
+        cb = &(*list_iter_);
+        ++list_iter_;
+      }
+      return cb;
+    }
+
+   private:
+    CallbackListBase<CallbackType>* list_;
+    typename std::list<CallbackType>::iterator list_iter_;
+  };
+
+  CallbackListBase() : active_iterator_count_(0) {}
+
+  ~CallbackListBase() {
+    DCHECK_EQ(0, active_iterator_count_);
+    DCHECK_EQ(0U, callbacks_.size());
+  }
+
+  // Returns an instance of a CallbackListBase::Iterator which can be used
+  // to run callbacks.
+  Iterator GetIterator() {
+    return Iterator(this);
+  }
+
+  // Compact the list: remove any entries which were NULLed out during
+  // iteration.
+  void Compact() {
+    typename std::list<CallbackType>::iterator it = callbacks_.begin();
+    bool updated = false;
+    while (it != callbacks_.end()) {
+      if ((*it).is_null()) {
+        updated = true;
+        it = callbacks_.erase(it);
+      } else {
+        ++it;
+      }
+
+      if (updated && !removal_callback_.is_null())
+        removal_callback_.Run();
+    }
+  }
+
+ private:
+  std::list<CallbackType> callbacks_;
+  int active_iterator_count_;
+  Closure removal_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallbackListBase);
+};
+
+}  // namespace internal
+
+template <typename Sig> class CallbackList;
+
+
+$range ARITY 0..MAX_ARITY
+$for ARITY [[
+$range ARG 1..ARITY
+
+$if ARITY == 0 [[
+template <>
+class CallbackList<void(void)>
+    : public internal::CallbackListBase<Callback<void(void)> > {
+]] $else [[
+template <$for ARG , [[typename A$(ARG)]]>
+class CallbackList<void($for ARG , [[A$(ARG)]])>
+    : public internal::CallbackListBase<Callback<void($for ARG , [[A$(ARG)]])> > {
+]]
+
+ public:
+$if ARITY == 0 [[
+
+  typedef Callback<void(void)> CallbackType;
+]] $else [[
+
+  typedef Callback<void($for ARG , [[A$(ARG)]])> CallbackType;
+]]
+
+
+  CallbackList() {}
+
+  void Notify($for ARG ,
+              [[typename internal::CallbackParamTraits<A$(ARG)>::ForwardType a$(ARG)]]) {
+$if ARITY == 0 [[
+
+    internal::CallbackListBase<CallbackType>::Iterator it =
+        this->GetIterator();
+]] $else [[
+
+    typename internal::CallbackListBase<CallbackType>::Iterator it =
+        this->GetIterator();
+]]
+
+    CallbackType* cb;
+    while ((cb = it.GetNext()) != NULL) {
+      cb->Run($for ARG , [[a$(ARG)]]);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackList);
+};
+
+
+]]  $$ for ARITY
+}  // namespace base
+
+#endif  // BASE_CALLBACK_LIST_H_