Skip to content

Latest commit

 

History

History
229 lines (179 loc) · 11.9 KB

README.md

File metadata and controls

229 lines (179 loc) · 11.9 KB
Raw

cpp-sort logo

Latest Release Conan Package Code Coverage Pitchfork Layout

It would be nice if only one or two of the sorting methods would dominate all of the others, regardless of application or the computer being used. But in fact, each method has its own peculiar virtues. [...] Thus we find that nearly all of the algorithms deserve to be remembered, since there are some applications in which they turn out to be best. — Donald Knuth, The Art Of Computer Programming, Volume 3

cpp-sort is a generic C++14 header-only sorting library. It revolves around one main generic sorting interface and provides several small tools to pick and/or design sorting algorithms. Using its basic sorting features should be trivial enough:

#include <array>
#include <iostream>
#include <cpp-sort/sorters/smooth_sorter.h>

int main()
{
    std::array<int, 5> arr = { 5, 8, 3, 2, 9 };
    cppsort::smooth_sort(arr);

    // prints 2 3 5 8 9
    for (int val: arr) {
        std::cout << val << ' ';
    }
}

The main features & the extra features

cpp-sort provides a full set of sorting-related features. Here are the main building blocks of the library:

Here is a more complete example of what can be done with the library:

#include <algorithm>
#include <cassert>
#include <forward_list>
#include <functional>
#include <vector>
#include <cpp-sort/adapters.h>
#include <cpp-sort/sorters.h>

int main()
{
    struct wrapper { int value; };

    std::forward_list<wrapper> li = { {5}, {8}, {3}, {2}, {9} };
    std::vector<wrapper> vec = { {5}, {8}, {3}, {2}, {9} };

    // When used, this sorter will use a pattern-defeating quicksort
    // to sort random-access collections, and a mergesort otherwise
    cppsort::hybrid_adapter<
        cppsort::pdq_sorter,
        cppsort::merge_sorter
    > sorter;

    // Sort li and vec in reverse order using their value member
    sorter(li, std::greater<>{}, &wrapper::value);
    sorter(vec, std::greater<>{}, &wrapper::value);

    assert(std::equal(
        li.begin(), li.end(),
        vec.begin(), vec.end(),
        [](const auto& lhs, const auto& rhs) { return lhs.value == rhs.value; }
    ));
}

Even when the sorting functions are used without the extra features, they still provide some interesting guarantees (ideas often taken from the Ranges TS):

  • They provide both an iterator and a range interface
  • When possible, they accept a custom comparator parameter
  • Most of them accept a projection parameter
  • They correctly handle proxy iterators with iter_swap and iter_move
  • They also work when iterators don't provide post-incrementation nor post-decrementation
  • The value types of the collections to be sorted need not be default-constructible
  • The value types of the collections to be sorted need not be copyable (only movable)
  • Stateless sorters can be converted to a function pointer for each overloaded operator()
  • Sorters are function objects: they can directly be passed as "overload sets" to other functions

You can read more about all the available tools and find some tutorials about using and extending cpp-sort in the wiki.

Benchmarks

The following graph has been generated with a script found in the benchmarks directory. It shows the time needed for a sorting algorithm to sort one million shuffled std::array<int, N> of sizes 0 to 32. It compares the sorters generally used to sort small arrays:

Benchmark speed of small sorts with increasing size for std::array<int>

These results were generated with MinGW-w64 g++ 10.1 with the compiler options -std=c++2a -O3 -march=native. That benchmark is merely an example to make this introduction look good. You can find more commented benchmarks in the dedicated wiki page.

Compiler support & tooling

Ubuntu builds status Windows builds status MacOS builds status

cpp-sort requires C++14 support, and should work with the following compilers:

  • g++5.5 or more recent. It is known not to work with some older g++5 versions.
  • clang++6.0 or more recent. It should work with clang++ versions all the way back to 3.8, but the CI pipeline doesn't have test for those anymore.
  • Visual Studio 2019 version 16.8.3 or more recent, only with /permissive-. A few features are still unavailable.
  • The versions of MinGW-w64 and AppleClang equivalent to the compilers mentioned above.
  • Clang is notably tested with both libstdc++ and libc++.

The compilers listed above are the ones used by the CI pipeline, and the library is also tested with the most recent versions of those compilers on a regular basis. All the other compiler versions in-between are untested, but should also work. Feel free to open an issue if it isn't the case.

The features in the library might differ depending on the C++ version used and on the compiler extensions enabled. Those changes are documented in the wiki.

The main repository contains additional support for standard tooling such as CMake or Conan. You can read more about those in the wiki.

Thanks

I got a new car. I just need to put it together. They’re easier to steal piece by piece. — Jarod Kintz, $3.33

Even though some parts of the library are original research and some others correspond to custom and rather naive implementations of standard sorting algorithms, cpp-sort also reuses a great deal of code and ideas from open-source projects, often altered to integrate seamlessly into the library. Here is a list of the external resources used to create this library. I hope that the many different licenses are compatible. If it is not the case, please contact me (or submit an issue) and we will see what can be done about it: