Lin-Q

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A simple, header-only, easy-to-use, and high-performance LINQ-like query library for C++ 🚀

This library provides a powerful set of query operations for collections, inspired by .NET's Language Integrated Query (LINQ)

✨ Features

• 📑 Header-only: Just include LinQ.hpp to get started
• ⌛ Deferred Execution: Operations like Where and Select are deferred until the results are actually needed
• 🎩 Powerful API:
  • Filtering: Where
  • Projection: Select
  • Sorting: OrderBy, OrderByDescending, ThenBy
  • Aggregation: Sum, Count, Average, Min, Max
  • Element: First, FirstOrDefault, Last, LastOrDefault, ElementAt
  • Quantifiers: Any, All
  • Set: Distinct, Union, Intersect, Except
  • Conversion: ToVector, ToMap, ToUnorderedMap, ToArray, ToCArray
  • ...

🛠️ Building the Project

Using xmake

xmake
xmake run example

Using CMake

mkdir build
cd build
cmake ..
cmake --build .
# Run the executable
./Release/example.exe

🚀 Usage Example

#include "LinQ.hpp"
#include <iostream>
#include <string>
#include <vector>

int main() {
  // Test with an integer array
  int intArray[] = {1, 2, 3, 4, 5};
  auto intQuery = LinQ::From(intArray)
                    .Select([](int x) { return x * x; });

  for (auto x : intQuery) {
    std::cout << x << " "; // Output: 1 4 9 16 25
  }
  std::cout << std::endl;

  // Test with a vector of strings
  std::vector<std::string> stringVector = {"apple", "banana", "cherry", "date", "fig"};
  auto stringQuery = LinQ::From(stringVector)
                          .Where([](const std::string& s) { return s.length() > 4; })
                          .Select([](const std::string& s) {
                            std::string upperString = s;
                            std::transform(upperString.begin(), upperString.end(), upperString.begin(), ::toupper);
                            return upperString;
                          })
                          .OrderByDescending([](const std::string& s) { return s; });

  for (const auto& s : stringQuery) {
    std::cout << s << " "; // Output: CHERRY BANANA APPLE
  }
  std::cout << std::endl;

  // Test ToMap with a single argument
  struct Person {
    int id;
    std::string name;
  };
  std::vector<Person> people = {{1, "ELDment"}, {2, "Ambr0se"}, {3, "利世"}};

  auto personMap = LinQ::From(people).ToMap([](const Person& p) { return p.id; });

  for (const auto& pair : personMap) {
    std::cout << "[" << pair.first << ": " << pair.second.name << "] "; // Output: [1: ELDment] [2: Ambr0se] [3: 利世]
  }
  std::cout << std::endl;

  return 0;
}

🤝 Contributing

Contributions, issues, and feature requests are welcome!