qtlinq — LINQ for Qt (Header‑Only, C++17)

A header-only LINQ-style query library for Qt, designed for QList<T>, providing a clean, fluent, expressive C#-style querying API in modern C++17.

✨ Features

• Header-only, single include
• Qt-friendly (QList<T>)
• C++17 compatible
• LINQ-like fluent API
• Stable ordering for all operations
• Automatic multi-strategy distinct()
• Polymorphic filtering (ofType<T>())
• Range-based iteration
• Optional-safe first element APIs
• QtTest unit tests
• Benchmark suite with huge datasets

🚀 Quick Example

#include <qtlinq/qtlinq.h>

QList<int> xs{1,2,3,4,5,6};

auto result =
    qlinq::from(xs)
        .where([](int x){ return x % 2 == 0; })
        .select([](int x){ return x * 10; })
        .toList();
// → { 20, 40, 60 }

📚 API Summary

Querying

• where(pred)
• select(func)
• selectMany(func)
• take(n)
• skip(n)
• reverse()
• distinct()

Ordering

• orderBy(key)
• orderByDescending(key)

First elements

• first()
• first(pred)
• firstOrDefault()
• firstOrDefault(pred)

Aggregation

• any(pred)
• all(pred)
• count() / count(value)
• min() / max()
• min(selector) / max(selector)
• minBy(selector) / maxBy(selector)
• sum(selector)
• aggregate(seed, func)

Polymorphic type filtering

• ofType<U>()

🛠 Installation (CMake)

target_include_directories(your_target PRIVATE path/to/qtlinq/include)

🤝 Contributing

Pull requests and issues are welcome.
Open an issue before large changes.

📄 License

Project uses GPLv3 License.