[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_