1 /*
2 * Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10 #ifndef RTC_BASE_EXPERIMENTS_STRUCT_PARAMETERS_PARSER_H_
11 #define RTC_BASE_EXPERIMENTS_STRUCT_PARAMETERS_PARSER_H_
12
13 #include <functional>
14 #include <map>
15 #include <memory>
16 #include <string>
17 #include <utility>
18 #include <vector>
19
20 #include "absl/memory/memory.h"
21 #include "absl/strings/string_view.h"
22 #include "absl/types/optional.h"
23 #include "rtc_base/experiments/field_trial_parser.h"
24 #include "rtc_base/experiments/field_trial_units.h"
25 #include "rtc_base/string_encode.h"
26
27 namespace webrtc {
28 namespace struct_parser_impl {
29 struct TypedMemberParser {
30 public:
31 bool (*parse)(const absl::string_view src, void* target);
32 void (*encode)(const void* src, std::string* target);
33 };
34
35 struct MemberParameter {
36 const char* key;
37 void* member_ptr;
38 TypedMemberParser parser;
39 };
40
41 template <typename T>
42 class TypedParser {
43 public:
44 static bool Parse(absl::string_view src, void* target);
45 static void Encode(const void* src, std::string* target);
46 };
47
48 // Instantiated in cc file to avoid duplication during compile. Add additional
49 // parsers as needed. Generally, try to use these suggested types even if the
50 // context where the value is used might require a different type. For instance,
51 // a size_t representing a packet size should use an int parameter as there's no
52 // need to support packet sizes larger than INT32_MAX.
53 extern template class TypedParser<bool>;
54 extern template class TypedParser<double>;
55 extern template class TypedParser<int>;
56 extern template class TypedParser<unsigned>;
57 extern template class TypedParser<absl::optional<double>>;
58 extern template class TypedParser<absl::optional<int>>;
59 extern template class TypedParser<absl::optional<unsigned>>;
60
61 extern template class TypedParser<DataRate>;
62 extern template class TypedParser<DataSize>;
63 extern template class TypedParser<TimeDelta>;
64 extern template class TypedParser<absl::optional<DataRate>>;
65 extern template class TypedParser<absl::optional<DataSize>>;
66 extern template class TypedParser<absl::optional<TimeDelta>>;
67
68 template <typename T>
AddMembers(MemberParameter * out,const char * key,T * member)69 void AddMembers(MemberParameter* out, const char* key, T* member) {
70 *out = MemberParameter{
71 key, member,
72 TypedMemberParser{&TypedParser<T>::Parse, &TypedParser<T>::Encode}};
73 }
74
75 template <typename T, typename... Args>
AddMembers(MemberParameter * out,const char * key,T * member,Args...args)76 void AddMembers(MemberParameter* out,
77 const char* key,
78 T* member,
79 Args... args) {
80 AddMembers(out, key, member);
81 AddMembers(++out, args...);
82 }
83 } // namespace struct_parser_impl
84
85 class StructParametersParser {
86 public:
87 template <typename T, typename... Args>
Create(const char * first_key,T * first_member,Args...args)88 static std::unique_ptr<StructParametersParser> Create(const char* first_key,
89 T* first_member,
90 Args... args) {
91 std::vector<struct_parser_impl::MemberParameter> members(
92 sizeof...(args) / 2 + 1);
93 struct_parser_impl::AddMembers(&members.front(), std::move(first_key),
94 first_member, args...);
95 return absl::WrapUnique(new StructParametersParser(std::move(members)));
96 }
97
98 void Parse(absl::string_view src);
99 std::string Encode() const;
100
101 private:
102 explicit StructParametersParser(
103 std::vector<struct_parser_impl::MemberParameter> members);
104
105 std::vector<struct_parser_impl::MemberParameter> members_;
106 };
107
108 } // namespace webrtc
109
110 #endif // RTC_BASE_EXPERIMENTS_STRUCT_PARAMETERS_PARSER_H_
111