1 // Copyright 2016 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_CLONE_EQUALS_UTIL_H_
6 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_CLONE_EQUALS_UTIL_H_
7 
8 #include <type_traits>
9 #include <unordered_map>
10 #include <vector>
11 
12 #include "base/optional.h"
13 #include "mojo/public/cpp/bindings/lib/template_util.h"
14 
15 namespace mojo {
16 namespace internal {
17 
18 template <typename T>
19 struct HasCloneMethod {
20   template <typename U>
21   static char Test(decltype(&U::Clone));
22   template <typename U>
23   static int Test(...);
24   static const bool value = sizeof(Test<T>(0)) == sizeof(char);
25 
26  private:
27   EnsureTypeIsComplete<T> check_t_;
28 };
29 
30 template <typename T, bool has_clone_method = HasCloneMethod<T>::value>
31 struct CloneTraits;
32 
33 template <typename T>
34 T Clone(const T& input);
35 
36 template <typename T>
37 struct CloneTraits<T, true> {
38   static T Clone(const T& input) { return input.Clone(); }
39 };
40 
41 template <typename T>
42 struct CloneTraits<T, false> {
43   static T Clone(const T& input) { return input; }
44 };
45 
46 template <typename T>
47 struct CloneTraits<base::Optional<T>, false> {
48   static base::Optional<T> Clone(const base::Optional<T>& input) {
49     if (!input)
50       return base::nullopt;
51 
52     return base::Optional<T>(internal::Clone(*input));
53   }
54 };
55 
56 template <typename T>
57 struct CloneTraits<std::vector<T>, false> {
58   static std::vector<T> Clone(const std::vector<T>& input) {
59     std::vector<T> result;
60     result.reserve(input.size());
61     for (const auto& element : input)
62       result.push_back(internal::Clone(element));
63 
64     return result;
65   }
66 };
67 
68 template <typename K, typename V>
69 struct CloneTraits<std::unordered_map<K, V>, false> {
70   static std::unordered_map<K, V> Clone(const std::unordered_map<K, V>& input) {
71     std::unordered_map<K, V> result;
72     for (const auto& element : input) {
73       result.insert(std::make_pair(internal::Clone(element.first),
74                                    internal::Clone(element.second)));
75     }
76     return result;
77   }
78 };
79 
80 template <typename T>
81 T Clone(const T& input) {
82   return CloneTraits<T>::Clone(input);
83 };
84 
85 template <typename T>
86 struct HasEqualsMethod {
87   template <typename U>
88   static char Test(decltype(&U::Equals));
89   template <typename U>
90   static int Test(...);
91   static const bool value = sizeof(Test<T>(0)) == sizeof(char);
92 
93  private:
94   EnsureTypeIsComplete<T> check_t_;
95 };
96 
97 template <typename T, bool has_equals_method = HasEqualsMethod<T>::value>
98 struct EqualsTraits;
99 
100 template <typename T>
101 bool Equals(const T& a, const T& b);
102 
103 template <typename T>
104 struct EqualsTraits<T, true> {
105   static bool Equals(const T& a, const T& b) { return a.Equals(b); }
106 };
107 
108 template <typename T>
109 struct EqualsTraits<T, false> {
110   static bool Equals(const T& a, const T& b) { return a == b; }
111 };
112 
113 template <typename T>
114 struct EqualsTraits<base::Optional<T>, false> {
115   static bool Equals(const base::Optional<T>& a, const base::Optional<T>& b) {
116     if (!a && !b)
117       return true;
118     if (!a || !b)
119       return false;
120 
121     return internal::Equals(*a, *b);
122   }
123 };
124 
125 template <typename T>
126 struct EqualsTraits<std::vector<T>, false> {
127   static bool Equals(const std::vector<T>& a, const std::vector<T>& b) {
128     if (a.size() != b.size())
129       return false;
130     for (size_t i = 0; i < a.size(); ++i) {
131       if (!internal::Equals(a[i], b[i]))
132         return false;
133     }
134     return true;
135   }
136 };
137 
138 template <typename K, typename V>
139 struct EqualsTraits<std::unordered_map<K, V>, false> {
140   static bool Equals(const std::unordered_map<K, V>& a,
141                      const std::unordered_map<K, V>& b) {
142     if (a.size() != b.size())
143       return false;
144     for (const auto& element : a) {
145       auto iter = b.find(element.first);
146       if (iter == b.end() || !internal::Equals(element.second, iter->second))
147         return false;
148     }
149     return true;
150   }
151 };
152 
153 template <typename T>
154 bool Equals(const T& a, const T& b) {
155   return EqualsTraits<T>::Equals(a, b);
156 }
157 
158 }  // namespace internal
159 }  // namespace mojo
160 
161 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_CLONE_EQUALS_UTIL_H_
162