Introduce OnceClosure and BindOnce

base/bind_unittest.cc

 // Copyright (c) 2012 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/bind.h"
 
 #include <memory>
 #include <utility>
 #include <vector>
 
@@ skipping 1051 matching lines @@
 
   int x = 1;
   base::Callback<void(int)> cb =
       Bind([](int* x, int i) { *x *= i; }, Unretained(&x));
   cb.Run(6);
   EXPECT_EQ(6, x);
   cb.Run(7);
   EXPECT_EQ(42, x);
 }
 
+TEST_F(BindTest, OneShotCallback) {
+  using internal::RepeatingClosure;
+  using internal::OneShotClosure;
+  using internal::BindOneShot;
+  using internal::BindRepeating;
+  using internal::OneShotCallback;
+
+  // Check if Callback variants have declarations of conversions as expected.
+  // Copy constructor and assignment of RepeatingCallback.
+  EXPECT_TRUE((std::is_constructible<

[dcheng, 2016/08/26 07:37:56]

Maybe these should be static_assert? Not sure if we have a convention for that,
but it makes more sense to do these at compile time anyway.

[tzik, 2016/08/30 11:31:40]

Done.

+      RepeatingClosure, const RepeatingClosure&>::value));
+  EXPECT_TRUE((is_assignable<
+      RepeatingClosure, const RepeatingClosure&>::value));
+
+  // Move constructor and assignment of RepeatingCallback.
+  EXPECT_TRUE((std::is_constructible<
+      RepeatingClosure, RepeatingClosure&&>::value));
+  EXPECT_TRUE((is_assignable<
+      RepeatingClosure, RepeatingClosure&&>::value));
+
+  // Conversions from OneShotCallback to RepeatingCallback.
+  EXPECT_FALSE((std::is_constructible<
+      RepeatingClosure, const OneShotClosure&>::value));
+  EXPECT_FALSE((is_assignable<
+      RepeatingClosure, const OneShotClosure&>::value));
+
+  // Destructive conversions from OneShotCallback to RepeatingCallback.
+  EXPECT_FALSE((std::is_constructible<
+      RepeatingClosure, OneShotClosure&&>::value));
+  EXPECT_FALSE((is_assignable<
+      RepeatingClosure, OneShotClosure&&>::value));
+
+  // Copy constructor and assignment of OneShotCallback.
+  EXPECT_FALSE((std::is_constructible<
+      OneShotClosure, const OneShotClosure&>::value));
+  EXPECT_FALSE((is_assignable<
+      OneShotClosure, const OneShotClosure&>::value));
+
+  // Move constructor and assignment of OneShotCallback.
+  EXPECT_TRUE((std::is_constructible<
+      OneShotClosure, OneShotClosure&&>::value));
+  EXPECT_TRUE((is_assignable<
+      OneShotClosure, OneShotClosure&&>::value));
+
+  // Conversions from RepeatingCallback to OneShotCallback.
+  EXPECT_TRUE((std::is_constructible<
+      OneShotClosure, const RepeatingClosure&>::value));
+  EXPECT_TRUE((is_assignable<
+      OneShotClosure, const RepeatingClosure&>::value));
+
+  // Destructive conversions from RepeatingCallback to OneShotCallback.
+  EXPECT_TRUE((std::is_constructible<
+      OneShotClosure, RepeatingClosure&&>::value));
+  EXPECT_TRUE((is_assignable<
+      OneShotClosure, RepeatingClosure&&>::value));
+
+  OneShotClosure cb = BindOneShot(&VoidPolymorphic<>::Run);
+  std::move(cb).Run();
+
+  // RepeatingCallback should be convertible to OneShotCallback.
+  OneShotClosure cb2 = BindRepeating(&VoidPolymorphic<>::Run);
+  std::move(cb2).Run();
+
+  RepeatingClosure cb3 = BindRepeating(&VoidPolymorphic<>::Run);
+  cb = cb3;
+  std::move(cb).Run();
+
+  cb = std::move(cb2);
+
+  OneShotCallback<void(int)> cb4 = BindOneShot(
+      &VoidPolymorphic<std::unique_ptr<int>, int>::Run, MakeUnique<int>(0));
+  BindOneShot(std::move(cb4), 1).Run();
+}
+
 // Callback construction and assignment tests.
 //   - Construction from an InvokerStorageHolder should not cause ref/deref.
 //   - Assignment from other callback should only cause one ref
 //
 // TODO(ajwong): Is there actually a way to test this?
 
 #if defined(OS_WIN)
 int __fastcall FastCallFunc(int n) {
   return n;
 }
@@ skipping 16 matching lines @@
 
 // Test null callbacks cause a DCHECK.
 TEST(BindDeathTest, NullCallback) {
   base::Callback<void(int)> null_cb;
   ASSERT_TRUE(null_cb.is_null());
   EXPECT_DCHECK_DEATH(base::Bind(null_cb, 42));
 }
 
 }  // namespace
 }  // namespace base