lhamot / rah

c++ range library "single-file"

rah

rah is range, header-only, "single-file" C++14/17 library.

What is a range library?

A range is anything that can be iterated. Typically in C++ something is a range if we can call begin(range) and end(range) on it.

A range library allows to create ranges and algorithms using them.

Why a new range library?

Yes there are some great range libraries in C++, like range-v3 and boost::range.

rah is not as complete as those libraries, but the goal of rah is to be "single file" and easy to integrate, read and understand. rah was designed with code simplicity as top priority.

What is inside rah

• Namespace rah contains a subset of usual algorithms present in <algorithm>, but useable in a range fashion
• More algorithms will be added soon

// Usual code with STL
std::cout << std::count(range.begin(), range.end(), 2);
// Using range algorithm
std::cout << rah::count(range, 2);

• rah::view contains functions to create ranges, actually doing work only when iterated (lazy), saving some memory and simplifying the code, especially when wanting to chain algorithms.

// Usual code with STL
std::vector<int> ints;
ints.resize(10);
std::iota(range.begin(), range.end(), 0);
std::vector<int> even;
std::copy_if(ints.begin(), ints.end(), std::back_inserter(even), [](int a) {return a % 2 == 0;});
std::vector<int> values;
std::transform(even.begin(), even.end(), std::back_inserter(values), [](int a) {return a * 2;});
for(int i: values)
    std::cout << i << std::endl;
// Using range algorithms
auto values = 
    rah::view::transform(
        rah::view::filter(
            rah::view::iota(0, 10), 
            [](int a) {return a % 2 == 0;})
        [](int a) {return a * 2;});
for(int i: values) // The job in done here, without memory allocation
    std::cout << i << std::endl;

• Most of views have a pipeable version, making theme easier to write and read.

// Using pipeable range algorithms
auto values = rah::view::iota(0, 10)
    | rah::view::filter([](int a) {return a % 2 == 0;}) 
    | rah::view::transform([](int a) {return a * 2;});
for(int i: values) // The job in done here, without memory allocation
    std::cout << i << std::endl;

License

rah is licensed under the Boost Software License

Documentation

You can find the doc here

Supported Compilers

• On Windows
  • Visual Studio 2015 (stdcpp14)
  • Visual Studio 2017 (stdcpp14 and stdcpp17)
  • clang 7 (-std=c++14 and -std=c++17)
• On Linux
  • clang 4 and 5 (-std=c++14 and -std=c++17)
  • gcc 7,8 and 9 (-std=c++14 and -std=c++17)

Continuous integration

Linux

Windows

How to use?

• Just include the rah.hpp file in your project
• range version of STL algorithms are in the rah namespace
• Views are in rah::view namespace
• Read the doc

The future of rah

• Wrap more std algorithms
• Add more ranges