istream_helper_util usage samples

istream_helper_util.t.cpp

//Source code by Fabio Galuppo
//C++ MasterClass - https://www.linkedin.com/company/cppmasterclass - https://cppmasterclass.com.br/
//Fabio Galuppo - http://member.acm.org/~fabiogaluppo - [email protected]
//March 2025

//g++ -O3 -std=c++20 istream_helper_util.t.cpp -o a.exe

#include "istream_helper_util.h"

#include <algorithm>
#include <fstream>
#include <functional>
#include <iostream>
#include <iterator>
#include <numeric>
#include <ranges>
#include <sstream>
#include <string>
#include <vector>
#include <utility>

/*
void example_1()
{
    std::cout << __FUNCTION__ << '\n';
    while (auto opt = istream_helper::Util::next(std::cin, std::identity{}))
        std::cout << '\t' << *opt << '\n';
}

void example_2()
{
    std::cout << __FUNCTION__ << '\n';
    while (auto opt = istream_helper::Util::next(std::cin))
        std::cout << '\t' << *opt << '\n';
}
*/

void example_3()
{
    std::cout << __FUNCTION__ << '\n';
    std::ifstream ifs("numbers.txt");
    while (auto opt = istream_helper::Util::next(ifs))
        std::cout << '\t' << *opt << '\n';
}

void example_4()
{
    std::cout << __FUNCTION__ << '\n';
    auto to_ints = [](const std::string& line) {
        std::istringstream iss{ line };
        std::ranges::istream_view<int> isv{ iss };
        std::vector<int> temp;
        std::ranges::copy(isv, std::back_inserter(temp));
        return temp;
    };
    std::ifstream ifs("numbers.txt");
    while (auto opt = istream_helper::Util::next(ifs, to_ints))
    {
        std::vector<int>& xs = *opt;
        std::cout << '\t';
        for (int x : xs) std::cout << x << ' ';
        std::cout << '\n';
    }
}

void example_5()
{
    std::cout << __FUNCTION__ << '\n';
    auto to_pair = [](const std::string& line) {
        std::istringstream iss{ line };
        std::ranges::istream_view<int> isv{ iss };
        std::vector<int> temp; std::ranges::copy(isv, std::back_inserter(temp));
        return std::make_pair(line, temp);;
    };
    std::ifstream ifs("numbers.txt");
    while (auto opt = istream_helper::Util::next(ifs, to_pair))
    {
        auto& xs = *opt;
        std::cout << "sum_all(" << xs.first << ") = "
                  << std::accumulate(xs.second.begin(), xs.second.end(), 0) << '\n';
    }
}

void example_6()
{
    std::cout << __FUNCTION__ << '\n';
    auto to_ints = [](const std::string& line) {
        std::istringstream iss{ line };
        std::ranges::istream_view<int> isv{ iss };
        std::vector<int> temp;
        std::ranges::copy(isv, std::back_inserter(temp));
        return temp;
    };
    std::ifstream ifs1("numbers.txt"), ifs2("numbers.txt");
    std::optional<std::string> opt1; std::optional<std::vector<int>> opt2;
    for (opt1 = istream_helper::Util::next(ifs1), opt2 = istream_helper::Util::next(ifs2, to_ints);
         opt1 && opt2;
         opt1 = istream_helper::Util::next(ifs1), opt2 = istream_helper::Util::next(ifs2, to_ints))
    {
        std::string& s = *opt1;
        std::vector<int>& xs = *opt2;
        std::cout << '\t' << s << " - ";
        for (int x : std::ranges::reverse_view(xs)) 
            std::cout << x << ' ';
        std::cout << '\n';
    }
}

void example_7()
{
    std::cout << __FUNCTION__ << '\n';
    auto to_ints = [](const std::string& line) {
        std::istringstream iss{ line };
        std::ranges::istream_view<int> isv{ iss };
        std::vector<int> temp;
        std::ranges::copy(isv, std::back_inserter(temp));
        return temp;
    };
    std::ifstream ifs("numbers.txt");
    std::vector<std::vector<int>> xss;
    istream_helper::Util::drain(ifs, to_ints, std::back_inserter(xss));
    for (const auto& xs : xss)
    {
        std::cout << '\t';
        for (int x : xs) std::cout << x << ' ';
        std::cout << '\n';
    }
}

void example_8()
{
    std::cout << __FUNCTION__ << '\n';
    std::ifstream ifs("numbers.txt");
    std::vector<std::string> xs;
    istream_helper::Util::drain(ifs, std::back_inserter(xs));
    for (const auto& s : xs)
        std::cout << '\t' << s << '\n';
}

void example_9()
{
    std::cout << __FUNCTION__ << '\n';
    std::ifstream ifs("numbers.txt");
    auto xs = istream_helper::Util::drain(ifs);
    for (const auto& s : xs)
        std::cout << '\t' << s << '\n';
}

void example_10()
{
    std::cout << __FUNCTION__ << '\n';
    auto xs = istream_helper::Util::drain(std::cin);
    for (const auto& s : xs)
        std::cout << '\t' << s << '\n';
}

int main()
{
    void(*fs[])(void) = {
        example_3, example_4, example_5, example_6, 
        example_7, example_8, example_9, example_10, 
    };
    for (auto f : fs)
        f();
    return 0;
}