1/*
2 * Copyright (C) 2016 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include <memory>
29#include <wtf/FastMalloc.h>
30
31namespace WTF {
32
33namespace Detail {
34
35template<typename Out, typename... In>
36class CallableWrapperBase {
37 WTF_MAKE_FAST_ALLOCATED;
38public:
39 virtual ~CallableWrapperBase() { }
40 virtual Out call(In...) = 0;
41};
42
43template<typename, typename, typename...> class CallableWrapper;
44
45template<typename CallableType, typename Out, typename... In>
46class CallableWrapper : public CallableWrapperBase<Out, In...> {
47public:
48 explicit CallableWrapper(CallableType&& callable)
49 : m_callable(WTFMove(callable)) { }
50 CallableWrapper(const CallableWrapper&) = delete;
51 CallableWrapper& operator=(const CallableWrapper&) = delete;
52 Out call(In... in) final { return m_callable(std::forward<In>(in)...); }
53private:
54 CallableType m_callable;
55};
56
57} // namespace Detail
58
59template<typename> class Function;
60
61template <typename Out, typename... In>
62class Function<Out(In...)> {
63 WTF_MAKE_FAST_ALLOCATED;
64public:
65 Function() = default;
66 Function(std::nullptr_t) { }
67
68 template<typename CallableType, class = typename std::enable_if<!(std::is_pointer<CallableType>::value && std::is_function<typename std::remove_pointer<CallableType>::type>::value) && std::is_rvalue_reference<CallableType&&>::value>::type>
69 Function(CallableType&& callable)
70 : m_callableWrapper(std::make_unique<Detail::CallableWrapper<CallableType, Out, In...>>(WTFMove(callable))) { }
71
72 template<typename FunctionType, class = typename std::enable_if<std::is_pointer<FunctionType>::value && std::is_function<typename std::remove_pointer<FunctionType>::type>::value>::type>
73 Function(FunctionType f)
74 : m_callableWrapper(std::make_unique<Detail::CallableWrapper<FunctionType, Out, In...>>(WTFMove(f))) { }
75
76 Out operator()(In... in) const
77 {
78 ASSERT(m_callableWrapper);
79 return m_callableWrapper->call(std::forward<In>(in)...);
80 }
81
82 explicit operator bool() const { return !!m_callableWrapper; }
83
84 template<typename CallableType, class = typename std::enable_if<!(std::is_pointer<CallableType>::value && std::is_function<typename std::remove_pointer<CallableType>::type>::value) && std::is_rvalue_reference<CallableType&&>::value>::type>
85 Function& operator=(CallableType&& callable)
86 {
87 m_callableWrapper = std::make_unique<Detail::CallableWrapper<CallableType, Out, In...>>(WTFMove(callable));
88 return *this;
89 }
90
91 template<typename FunctionType, class = typename std::enable_if<std::is_pointer<FunctionType>::value && std::is_function<typename std::remove_pointer<FunctionType>::type>::value>::type>
92 Function& operator=(FunctionType f)
93 {
94 m_callableWrapper = std::make_unique<Detail::CallableWrapper<FunctionType, Out, In...>>(WTFMove(f));
95 return *this;
96 }
97
98 Function& operator=(std::nullptr_t)
99 {
100 m_callableWrapper = nullptr;
101 return *this;
102 }
103
104private:
105 std::unique_ptr<Detail::CallableWrapperBase<Out, In...>> m_callableWrapper;
106};
107
108} // namespace WTF
109
110using WTF::Function;
111