[WIP][Base] Use variadic template for Callback and Bind

base/bind.h.pump

Index: base/bind.h.pump
diff --git a/base/bind.h.pump b/base/bind.h.pump
deleted file mode 100644
index 2cdd7d5e49857eda6dc86a3d29abe6dc1247c5c9..0000000000000000000000000000000000000000
--- a/base/bind.h.pump
+++ /dev/null
@@ -1,153 +0,0 @@
-$$ This is a pump file for generating file templates.  Pump is a python
-$$ script that is part of the Google Test suite of utilities.  Description
-$$ can be found here:
-$$
-$$ http://code.google.com/p/googletest/wiki/PumpManual
-$$
-
-$$
-$$ MAX_ARITY controls the number of arguments that Bind() supports.
-$$ The amount of code, and more importantly, the number of template types
-$$ generated by pump grows at O(MAX_ARITY^2).
-$$
-$$ We tried going to 11 and found it imposed an extra 10 penalty on windows
-$$ cycle times compared to our original baseline of 6.
-$$
-$$ Currently 7 is chosen as a compromise between supporting a convenient
-$$ number of arguments and keeping compile times low.  At 7, we have 115
-$$ templates being generated by pump.
-$$
-$$ Be careful when adjusting this number.  If people find a need to bind
-$$ a larger number of arguments, consider refactoring the function to use
-$$ a param struct instead of raising the MAX_ARITY.
-$$
-$$ See http://crbug.com/98542 for more context.
-$$
-$var MAX_ARITY = 7
-
-// 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.
-
-#ifndef BASE_BIND_H_
-#define BASE_BIND_H_
-
-#include "base/bind_internal.h"
-#include "base/callback_internal.h"
-
-// -----------------------------------------------------------------------------
-// Usage documentation
-// -----------------------------------------------------------------------------
-//
-// See base/callback.h for documentation.
-//
-//
-// -----------------------------------------------------------------------------
-// Implementation notes
-// -----------------------------------------------------------------------------
-//
-// If you're reading the implementation, before proceeding further, you should
-// read the top comment of base/bind_internal.h for a definition of common
-// terms and concepts.
-//
-// RETURN TYPES
-//
-// Though Bind()'s result is meant to be stored in a Callback<> type, it
-// cannot actually return the exact type without requiring a large amount
-// of extra template specializations. The problem is that in order to
-// discern the correct specialization of Callback<>, Bind would need to
-// unwrap the function signature to determine the signature's arity, and
-// whether or not it is a method.
-//
-// Each unique combination of (arity, function_type, num_prebound) where
-// function_type is one of {function, method, const_method} would require
-// one specialization.  We eventually have to do a similar number of
-// specializations anyways in the implementation (see the Invoker<>,
-// classes).  However, it is avoidable in Bind if we return the result
-// via an indirection like we do below.
-//
-// TODO(ajwong): We might be able to avoid this now, but need to test.
-//
-// It is possible to move most of the COMPILE_ASSERT asserts into BindState<>,
-// but it feels a little nicer to have the asserts here so people do not
-// need to crack open bind_internal.h.  On the other hand, it makes Bind()
-// harder to read.
-
-namespace base {
-
-$range ARITY 0..MAX_ARITY
-$for ARITY [[
-$range ARG 1..ARITY
-
-template <typename Functor[[]]
-$if ARITY > 0 [[, ]] $for ARG , [[typename P$(ARG)]]>
-base::Callback<
-    typename internal::BindState<
-        typename internal::FunctorTraits<Functor>::RunnableType,
-        typename internal::FunctorTraits<Functor>::RunType,
-        void($for ARG , [[typename internal::CallbackParamTraits<P$(ARG)>::StorageType]])>
-            ::UnboundRunType>
-Bind(Functor functor
-$if ARITY > 0 [[, ]] $for ARG , [[const P$(ARG)& p$(ARG)]]) {
-  // Typedefs for how to store and run the functor.
-  typedef typename internal::FunctorTraits<Functor>::RunnableType RunnableType;
-  typedef typename internal::FunctorTraits<Functor>::RunType RunType;
-
-$if ARITY > 0 [[
-
-  // Use RunnableType::RunType instead of RunType above because our
-  // checks should below for bound references need to know what the actual
-  // functor is going to interpret the argument as.
-  typedef internal::FunctionTraits<typename RunnableType::RunType>
-      BoundFunctorTraits;
-
-  // Do not allow binding a non-const reference parameter. Non-const reference
-  // parameters are disallowed by the Google style guide.  Also, binding a
-  // non-const reference parameter can make for subtle bugs because the
-  // invoked function will receive a reference to the stored copy of the
-  // argument and not the original.
-  COMPILE_ASSERT(
-      !($for ARG || [[
-is_non_const_reference<typename BoundFunctorTraits::A$(ARG)Type>::value ]]),
-      do_not_bind_functions_with_nonconst_ref);
-
-]]
-
-
-$for ARG [[
-
-
-$if ARG == 1 [[
-  // For methods, we need to be careful for parameter 1.  We do not require
-  // a scoped_refptr because BindState<> itself takes care of AddRef() for
-  // methods. We also disallow binding of an array as the method's target
-  // object.
-  COMPILE_ASSERT(
-      internal::HasIsMethodTag<RunnableType>::value ||
-          !internal::NeedsScopedRefptrButGetsRawPtr<P$(ARG)>::value,
-      p$(ARG)_is_refcounted_type_and_needs_scoped_refptr);
-  COMPILE_ASSERT(!internal::HasIsMethodTag<RunnableType>::value ||
-                     !is_array<P$(ARG)>::value,
-                 first_bound_argument_to_method_cannot_be_array);
-]] $else [[
-  COMPILE_ASSERT(!internal::NeedsScopedRefptrButGetsRawPtr<P$(ARG)>::value,
-                 p$(ARG)_is_refcounted_type_and_needs_scoped_refptr);
-]]  $$ $if ARG
-
-]]  $$ $for ARG
-
-  typedef internal::BindState<RunnableType, RunType, [[]]
-void($for ARG , [[typename internal::CallbackParamTraits<P$(ARG)>::StorageType]])> [[]]
-BindState;
-
-
-  return Callback<typename BindState::UnboundRunType>(
-      new BindState(internal::MakeRunnable(functor)[[]]
-$if ARITY > 0 [[, ]] $for ARG , [[p$(ARG)]]));
-}
-
-]]  $$ for ARITY
-
-}  // namespace base
-
-#endif  // BASE_BIND_H_