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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UTIL_STD_UTIL_H_
#define UTIL_STD_UTIL_H_
#include <algorithm>
#include <map>
#include <string>
#include <utility>
#include <vector>
#include "absl/algorithm/container.h"
namespace openscreen {
template <typename T, size_t N>
constexpr size_t countof(T (&array)[N]) {
return N;
// std::basic_string::data() has no mutable overload prior to C++17 [1].
// Hence this overload is provided.
// Note: str[0] is safe even for empty strings, as they are guaranteed to be
// null-terminated [2].
// [1]
// [2]
template <typename CharT, typename Traits, typename Allocator>
CharT* data(std::basic_string<CharT, Traits, Allocator>& str) {
return std::addressof(str[0]);
template <typename Key, typename Value>
void RemoveValueFromMap(std::map<Key, Value*>* map, Value* value) {
for (auto it = map->begin(); it != map->end();) {
if (it->second == value) {
it = map->erase(it);
} else {
template <typename ForwardIteratingContainer>
bool AreElementsSortedAndUnique(const ForwardIteratingContainer& c) {
return absl::c_is_sorted(c) && (absl::c_adjacent_find(c) == c.end());
template <typename RandomAccessContainer>
void SortAndDedupeElements(RandomAccessContainer* c) {
std::sort(c->begin(), c->end());
const auto new_end = std::unique(c->begin(), c->end());
c->erase(new_end, c->end());
// Append the provided elements together into a single vector. This can be
// useful when creating a vector of variadic templates in the ctor.
// This is the base case for the recursion
template <typename T>
std::vector<T>&& Append(std::vector<T>&& so_far) {
return std::move(so_far);
// This is the recursive call. Depending on the number of remaining elements, it
// either calls into itself or into the above base case.
template <typename T, typename TFirst, typename... TOthers>
std::vector<T>&& Append(std::vector<T>&& so_far,
TFirst&& new_element,
TOthers&&... new_elements) {
return Append(std::move(so_far), std::move(new_elements)...);
// Creates an empty vector with |size| elements reserved. Intended to be used as
// GetEmptyVectorOfSize<T>(sizeof...(variadic_input))
template <typename T>
std::vector<T> GetVectorWithCapacity(size_t size) {
std::vector<T> results;
return results;
} // namespace openscreen
#endif // UTIL_STD_UTIL_H_