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/*
* 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
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