c++ 函数式编程-管道流水线

c++ 管道式函数式编程

// C
#ifndef _GLIBCXX_NO_ASSERT
#include <cassert>
#endif
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#if __cplusplus >= 201103L
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
// #include <cstdalign>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>
#endif
// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#if __cplusplus >= 201103L
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <type_traits>
#include <typeindex>
#include <unordered_map>
#include <unordered_set>
#endif
using namespace std;

template <typename T, class F>
auto operator|(T&& param, F&& f) -> decltype(std::forward<F>(f)(std::forward<T>(param))) {
    return (std::forward<F>(f)(std::forward<T>(param)));
}

template <class F, typename Tuple, size_t... I>
auto process(F&& f, Tuple&& tu, index_sequence<I...> rr) {
    return std::forward<F>(f)(get<I>(std::forward<Tuple>(tu))...);
}

template <typename Tuple, class F>
auto operator|(Tuple&& tu, F&& f) -> decltype(process(forward<F>(f), forward<Tuple>(tu), make_index_sequence<tuple_size<typename remove_reference<Tuple>::type>::value>())) {
    return process(forward<F>(f), forward<Tuple>(tu), make_index_sequence<tuple_size<typename remove_reference<Tuple>::type>::value>());
}

auto sorter = [](auto&& nums) -> decltype(auto) {
    sort(nums.begin(), nums.end());
    return (nums);
};

auto uniquer = [](auto&& nums) -> decltype(auto) {
    nums.erase(unique(nums.begin(), nums.end()), nums.end());
    return (nums);
};

auto printer = [](auto&& nums) {
    for (auto v : nums) {
        cout << v << " ";
    }
    cout << endl;
};

string generate_data(string filename, int low, int high, int times) {
    ofstream os(filename);
    os.clear();
    random_device rd;
    mt19937 mt(rd());
    uniform_int_distribution<int> u(low, high);
    for (int i = 0; i < times; i++) {
        os << u(mt) << endl;
    }
    return filename;
}

vector<int> read_data(string filename) {
    ifstream is(filename);
    int num;
    vector<int> vec;
    while (!is.eof()) {
        is >> num;
        vec.push_back(num);
    }
    return vec;
}

unordered_map<int, int> statis_times(vector<int>&& nums) {
    unordered_map<int, int> mp;
    for (auto v : nums) {
        mp[v]++;
    }
    return mp;
}

vector<pair<int, int>> value_key_reverse(unordered_map<int, int>&& mp) {
    vector<pair<int, int>> vec;
    for (auto& kv : mp) {
        vec.push_back({kv.second, kv.first});
    }
    return vec;
}

auto sort_greater = [](vector<pair<int, int>>&& nums) {
    sort(nums.begin(), nums.end(), greater<>{});
    return make_tuple(nums, 20);
};

void top_print(vector<pair<int, int>> data, int top) {
    for (int i = 0; i < top && i < data.size(); i++) {
        cout << data[i].second << "\t" << data[i].first << endl;
    }
}

int main() {
    // // 单参函数式编程
    vector<int>{2, 1, 3, 5, 2} | sorter | uniquer | printer;
    // 读文件， 统计每个数出现次数，并打印前10
    cout << "管道 \n";
    make_tuple("./radom.txt", 0, 10, 100) | generate_data | read_data | statis_times | value_key_reverse | sort_greater | top_print;
}
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