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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/language/core/browser/language_usage_metrics.h"
#include <stddef.h>
#include <set>
#include <string_view>
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/string_tokenizer.h"
#include "components/language/core/browser/url_language_histogram.h"
namespace language {
// static
void LanguageUsageMetrics::RecordAcceptLanguages(
std::string_view accept_languages) {
std::vector<int> languages = ParseAcceptLanguages(accept_languages);
UMA_HISTOGRAM_COUNTS_100("LanguageUsage.AcceptLanguage.Count",
languages.size());
for (int language_code : languages) {
base::UmaHistogramSparse("LanguageUsage.AcceptLanguage", language_code);
}
if (!languages.empty()) {
base::UmaHistogramSparse("LanguageUsage.AcceptLanguage.FirstAcceptLanguage",
languages[0]);
}
}
// static
void LanguageUsageMetrics::RecordPageLanguages(
const language::UrlLanguageHistogram& language_counts) {
const float kMinLanguageFrequency = 0.05;
std::vector<language::UrlLanguageHistogram::LanguageInfo> top_languages =
language_counts.GetTopLanguages();
for (const language::UrlLanguageHistogram::LanguageInfo& language_info :
top_languages) {
if (language_info.frequency < kMinLanguageFrequency) {
continue;
}
const int language_code = ToLanguageCodeHash(language_info.language_code);
if (language_code != 0) {
base::UmaHistogramSparse("LanguageUsage.MostFrequentPageLanguages",
language_code);
}
}
}
// static
int LanguageUsageMetrics::ToLanguageCodeHash(std::string_view locale) {
std::string_view language_part =
locale.substr(0U, locale.find_first_of("-_"));
int language_code = 0;
for (size_t i = 0U; i < language_part.size(); ++i) {
// It's undefined behavior in C++ to left-shift a signed int past its sign
// bit, so only shift until the int's sign bit is reached. Note that it's
// safe to shift up to sizeof(int) times because each character is only
// added if it's between 'a' and 'z', which all have a 0 in their 7th bit.
// For example, for 4-byte ints, "zzzz" would be converted to 0x7A7A7A7A,
// which doesn't quite reach the sign bit, making it safe to insert up to 4
// characters.
if (i == sizeof(language_code))
return 0;
char ch = language_part[i];
if ('A' <= ch && ch <= 'Z')
ch += ('a' - 'A');
else if (ch < 'a' || 'z' < ch)
return 0;
language_code <<= 8;
language_code += ch;
}
return language_code;
}
// static
std::vector<int> LanguageUsageMetrics::ParseAcceptLanguages(
std::string_view accept_languages) {
std::set<int> visited_languages;
std::vector<int> languages;
base::StringViewTokenizer locales(accept_languages, ",");
while (locales.GetNext()) {
const int language_hash = ToLanguageCodeHash(locales.token_piece());
if (language_hash != 0 && visited_languages.insert(language_hash).second) {
languages.push_back(language_hash);
}
}
return languages;
}
} // namespace language
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