| /* |
| * Copyright (c) 2020 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #include "api/field_trials.h" |
| |
| #include <memory> |
| #include <string> |
| #include <utility> |
| |
| #include "absl/base/nullability.h" |
| #include "absl/memory/memory.h" |
| #include "absl/strings/string_view.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/containers/flat_map.h" |
| |
| namespace webrtc { |
| namespace { |
| |
| absl::string_view NextKeyOrValue(absl::string_view& s) { |
| absl::string_view::size_type separator_pos = s.find('/'); |
| if (separator_pos == absl::string_view::npos) { |
| // Missing separator '/' after field trial key or value. |
| return ""; |
| } |
| absl::string_view result = s.substr(0, separator_pos); |
| s.remove_prefix(separator_pos + 1); |
| return result; |
| } |
| |
| bool Parse(absl::string_view s, |
| flat_map<std::string, std::string>& key_value_map) { |
| while (!s.empty()) { |
| absl::string_view key = NextKeyOrValue(s); |
| absl::string_view value = NextKeyOrValue(s); |
| if (key.empty() || value.empty()) { |
| return false; |
| } |
| |
| auto it = key_value_map.emplace(key, value).first; |
| if (it->second != value) { |
| // Duplicate trials with different values is not fine. |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| } // namespace |
| |
| absl_nullable std::unique_ptr<FieldTrials> FieldTrials::Create( |
| absl::string_view s) { |
| flat_map<std::string, std::string> key_value_map; |
| if (!Parse(s, key_value_map)) { |
| return nullptr; |
| } |
| // Using `new` to access a private constructor. |
| return absl::WrapUnique(new FieldTrials(std::move(key_value_map))); |
| } |
| |
| FieldTrials::FieldTrials(absl::string_view s) { |
| RTC_CHECK(Parse(s, key_value_map_)); |
| } |
| |
| void FieldTrials::Merge(const FieldTrials& other) { |
| for (const auto& [trial, group] : other.key_value_map_) { |
| key_value_map_.insert_or_assign(trial, group); |
| } |
| } |
| |
| void FieldTrials::Set(absl::string_view trial, absl::string_view group) { |
| RTC_CHECK(!trial.empty()); |
| RTC_CHECK_EQ(trial.find('/'), absl::string_view::npos); |
| RTC_CHECK_EQ(group.find('/'), absl::string_view::npos); |
| if (group.empty()) { |
| key_value_map_.erase(trial); |
| } else { |
| key_value_map_.insert_or_assign(trial, group); |
| } |
| } |
| |
| std::string FieldTrials::GetValue(absl::string_view key) const { |
| auto it = key_value_map_.find(key); |
| if (it != key_value_map_.end()) { |
| return it->second; |
| } |
| |
| return ""; |
| } |
| |
| } // namespace webrtc |