xref: /aosp_15_r20/external/openscreen/util/std_util.h (revision 3f982cf4871df8771c9d4abe6e9a6f8d829b2736)

// 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>

// TODO: This header is included in the openscreen discovery public headers (dns_sd_instance.h),
// which exposes this abseil header. Need to figure out a way to hide it.
#if 0
#include "absl/algorithm/container.h"
#endif
#include "util/stringprintf.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] http://en.cppreference.com/w/cpp/string/basic_string/data
// [2] http://en.cppreference.com/w/cpp/string/basic_string/operator_at
template <typename CharT, typename Traits, typename Allocator>
CharT* data(std::basic_string<CharT, Traits, Allocator>& str) {
  return std::addressof(str[0]);
}

std::string Join(const std::vector<std::string>& strings,
                 const char* delimiter);

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 {
      ++it;
    }
  }
}

#if 0
template <typename ForwardIteratingContainer>
bool AreElementsSortedAndUnique(const ForwardIteratingContainer& c) {
  return absl::c_is_sorted(c) && (absl::c_adjacent_find(c) == c.end());
}
#endif

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) {
  so_far.push_back(std::move(new_element));
  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;
  results.reserve(size);
  return results;
}

}  // namespace openscreen

#endif  // UTIL_STD_UTIL_H_