tdlight/tdutils/td/utils/algorithm.h

189 lines
3.7 KiB
C++

//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2021
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
#include "td/utils/common.h"
#include <functional>
#include <type_traits>
#include <utility>
namespace td {
namespace detail {
template <typename V>
struct transform_helper {
template <class Func>
auto transform(const V &v, const Func &f) {
vector<decltype(f(*v.begin()))> result;
result.reserve(v.size());
for (auto &x : v) {
result.push_back(f(x));
}
return result;
}
template <class Func>
auto transform(V &&v, const Func &f) {
vector<decltype(f(std::move(*v.begin())))> result;
result.reserve(v.size());
for (auto &x : v) {
result.push_back(f(std::move(x)));
}
return result;
}
};
} // namespace detail
template <class V, class Func>
auto transform(V &&v, const Func &f) {
return detail::transform_helper<std::decay_t<V>>().transform(std::forward<V>(v), f);
}
template <class V, class Func>
bool remove_if(V &v, const Func &f) {
size_t i = 0;
while (i != v.size() && !f(v[i])) {
i++;
}
if (i == v.size()) {
return false;
}
size_t j = i;
while (++i != v.size()) {
if (!f(v[i])) {
v[j++] = std::move(v[i]);
}
}
v.erase(v.begin() + j, v.end());
return true;
}
template <class V, class T>
bool remove(V &v, const T &value) {
size_t i = 0;
while (i != v.size() && v[i] != value) {
i++;
}
if (i == v.size()) {
return false;
}
size_t j = i;
while (++i != v.size()) {
if (v[i] != value) {
v[j++] = std::move(v[i]);
}
}
v.erase(v.begin() + j, v.end());
return true;
}
template <class V>
void unique(V &v) {
if (v.empty()) {
return;
}
// use ADL to find std::sort
// caller will need to #include <algorithm>
sort(v.begin(), v.end(), std::less<void>());
size_t j = 1;
for (size_t i = 1; i < v.size(); i++) {
if (v[i] != v[i - 1]) {
if (i != j) {
v[j] = std::move(v[i]);
}
j++;
}
}
v.resize(j);
}
template <class V, class T>
bool contains(const V &v, const T &value) {
for (auto &x : v) {
if (x == value) {
return true;
}
}
return false;
}
template <class T>
void reset_to_empty(T &value) {
using std::swap;
std::decay_t<T> tmp;
swap(tmp, value);
}
template <class T>
void append(vector<T> &destination, const vector<T> &source) {
destination.insert(destination.end(), source.begin(), source.end());
}
template <class T>
void append(vector<T> &destination, vector<T> &&source) {
if (destination.empty()) {
destination.swap(source);
return;
}
destination.reserve(destination.size() + source.size());
for (auto &elem : source) {
destination.push_back(std::move(elem));
}
reset_to_empty(source);
}
template <class T>
void combine(vector<T> &destination, const vector<T> &source) {
append(destination, source);
}
template <class T>
void combine(vector<T> &destination, vector<T> &&source) {
if (destination.size() < source.size()) {
destination.swap(source);
}
if (source.empty()) {
return;
}
destination.reserve(destination.size() + source.size());
for (auto &elem : source) {
destination.push_back(std::move(elem));
}
reset_to_empty(source);
}
namespace detail {
template <typename T>
struct reversion_wrapper {
T &iterable;
};
template <typename T>
auto begin(reversion_wrapper<T> w) {
return w.iterable.rbegin();
}
template <typename T>
auto end(reversion_wrapper<T> w) {
return w.iterable.rend();
}
} // namespace detail
template <typename T>
detail::reversion_wrapper<T> reversed(T &iterable) {
return {iterable};
}
} // namespace td