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https://github.com/timsort/cpp-TimSort
A C++ implementation of timsort
https://github.com/timsort/cpp-TimSort
algorithm c-plus-plus sort sorting
Last synced: about 1 month ago
JSON representation
A C++ implementation of timsort
- Host: GitHub
- URL: https://github.com/timsort/cpp-TimSort
- Owner: timsort
- License: mit
- Created: 2011-09-20T15:31:09.000Z (over 12 years ago)
- Default Branch: 3.x.y
- Last Pushed: 2024-01-28T20:22:16.000Z (4 months ago)
- Last Synced: 2024-04-25T15:10:26.342Z (about 1 month ago)
- Topics: algorithm, c-plus-plus, sort, sorting
- Language: C++
- Homepage:
- Size: 257 KB
- Stars: 281
- Watchers: 19
- Forks: 43
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Lists
- awesome-cpp - Timsort - A templated stable sorting function which outperforms quicksort-based algorithms including std::sort, for reversed or semi-sorted data. [MIT] (Sorting)
- awesome-code-for-gamedev - timesort/cpp-TimeSort - A C++ implementation of timsort (Coding / C++ Data Structures and Algorithms)
README
[](https://github.com/timsort/cpp-TimSort/releases/tag/v3.0.0)
[](https://conan.io/center/recipes/timsort?version=3.0.0)
[](https://github.com/vector-of-bool/pitchfork)
## TimSort
A C++ implementation of TimSort, an O(n log n) stable sorting algorithm, ported from Python's and OpenJDK's.
See also the following links for a detailed description of TimSort:
* http://svn.python.org/projects/python/trunk/Objects/listsort.txt
* http://en.wikipedia.org/wiki/Timsort
This version of the library requires at least C++20. Older versions of the library, available in different branches,
offer support for older standards though implement fewer features:
* Branch `2.x.y` is compatible with C++11, and is slightly more permissive in some reagard due to the lack of
concepts to constrain its interface (it notaby supports iterators without postfix operator++/--).
* Branch `1.x.y` is compatible with C++03.
Older versions are not actively maintained anymore. If you need extended support for those, please open specific
issues for the problems you want solved.
According to the benchmarks, `gfx::timsort` is slower than [`std::ranges::sort`][std-sort] on randomized sequences,
but faster on partially-sorted ones. It can be used as a drop-in replacement for [`std::ranges::stable_sort`][std-stable-sort],
with the difference that it can't fall back to a O(n log² n) algorithm when there isn't enough extra heap memory
available.
Merging sorted ranges efficiently is an important part of the TimSort algorithm. This library exposes `gfx::timmerge`
in the public API, a drop-in replacement for [`std::ranges::inplace_merge`][std-inplace-merge] with the difference
that it can't fall back to a O(n log n) algorithm when there isn't enough extra heap memory available. According to
the benchmarks, `gfx::timmerge` is slower than `std::ranges::inplace_merge` on heavily/randomly overlapping subranges
of simple elements, but it is faster for complex elements such as `std::string`, and on sparsely overlapping subranges.
The ibrary exposes the following functions in namespace `gfx`:
```cpp
// timsort
template <
std::random_access_iterator Iterator,
std::sentinel_for Sentinel,
typename Compare = std::ranges::less,
typename Projection = std::identity
>
requires std::sortable
auto timsort(Iterator first, Sentinel last,
Compare compare={}, Projection projection={})
-> Iterator;
template <
std::ranges::random_access_range Range,
typename Compare = std::ranges::less,
typename Projection = std::identity
>
requires std::sortable, Compare, Projection>
auto timsort(Range &range, Compare compare={}, Projection projection={})
-> std::ranges::borrowed_iterator_t;
// timmerge
template <
std::random_access_iterator Iterator,
std::sentinel_for Sentinel,
typename Compare = std::ranges::less,
typename Projection = std::identity
>
requires std::sortable
auto timmerge(Iterator first, Iterator middle, Sentinel last,
Compare compare={}, Projection projection={})
-> Iterator;
template <
std::ranges::random_access_range Range,
typename Compare = std::ranges::less,
typename Projection = std::identity
>
requires std::sortable, Compare, Projection>
auto timmerge(Range &&range, std::ranges::iterator_t middle,
Compare compare={}, Projection projection={})
-> std::ranges::borrowed_iterator_t;
```
## EXAMPLE
Example of using timsort with a defaulted comparison function and a projection function to sort a vector of strings
by length:
```cpp
#include
#include
#include
size_t len(const std::string& str) {
return str.size();
}
// Sort a vector of strings by length
std::vector collection = { /* ... */ };
gfx::timsort(collection, {}, &len);
```
## INSTALLATION & COMPATIBILITY
[](https://github.com/timsort/cpp-TimSort/actions/workflows/build-ubuntu.yml)
[](https://github.com/timsort/cpp-TimSort/actions/workflows/build-msvc.yml)
[](https://github.com/timsort/cpp-TimSort/actions/workflows/build-mingw.yml)
[](https://github.com/timsort/cpp-TimSort/actions/workflows/build-macos.yml)
The library is tested with the following compilers:
* Ubuntu: GCC 10, Clang 11
* Windows: MSVC 19.37.32826.1, MinGW-w64 GCC 12
* MacOS: GCC 10, Clang 17
The library can be installed on the system via [CMake][cmake] (at least 3.14) with the following commands:
```sh
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --install build
```
Alternatively the library is also available [Conan Center][conan-center] and can be directly installed in your local
[Conan][conan] cache with the following command:
```sh
conan install --requires=timsort/3.0.0
```
## DIAGNOSTICS & INFORMATION
The following configuration macros allow `gfx::timsort` and `gfx::timmerge` to emit diagnostics, which can be helpful
to diagnose issues:
* Defining `GFX_TIMSORT_ENABLE_ASSERT` light inserts assertions in key locations in the algorithm to avoid logic errors.
* Defining `GFX_TIMSORT_ENABLE_AUDIT` inserts assertions that verify pre- and postconditions. These verifications can
slow the algorithm down significantly. Enable the audits only while testing or debugging. Enabling audits automatically
enables lighter assertions too.
* Defining `GFX_TIMSORT_ENABLE_LOG` inserts logs in key locations, which allow to follow more closely the flow of the
algorithm.
**cpp-TimSort** follows semantic versioning and provides the following macros to retrieve the current major, minor
and patch versions:
```cpp
GFX_TIMSORT_VERSION_MAJOR
GFX_TIMSORT_VERSION_MINOR
GFX_TIMSORT_VERSION_PATCH
```
## TESTS
The tests are written with Catch2 and can be compiled with CMake and run through CTest.
When using the project's main `CMakeLists.txt`, the CMake option `BUILD_TESTING` is `ON` by default unless the
project is included as a subdirectory. The following CMake options are available to change the way the tests are
built with CMake:
* `GFX_TIMSORT_USE_VALGRIND`: if `ON`, the tests will be run through Valgrind (`OFF` by default)
* `GFX_TIMSORT_SANITIZE`: this variable takes a comma-separated list of sanitizers options to run the tests (empty by default)
## BENCHMARKS
Benchmarks are available in the `benchmarks` subdirectory, and can be constructed directly by passing the option
`-DBUILD_BENCHMARKS=ON` to CMake during the configuration step.
Example bench_sort output (timing scale: sec.):
c++ -v
Apple LLVM version 7.0.0 (clang-700.0.72)
Target: x86_64-apple-darwin14.5.0
Thread model: posix
c++ -I. -Wall -Wextra -g -DNDEBUG -O2 -std=c++11 example/bench.cpp -o .bin/bench
./.bin/bench
RANDOMIZED SEQUENCE
[int]
size 100000
std::sort 0.695253
std::stable_sort 0.868916
timsort 1.255825
[std::string]
size 100000
std::sort 3.438217
std::stable_sort 4.122629
timsort 5.791845
REVERSED SEQUENCE
[int]
size 100000
std::sort 0.045461
std::stable_sort 0.575431
timsort 0.019139
[std::string]
size 100000
std::sort 0.586707
std::stable_sort 2.715778
timsort 0.345099
SORTED SEQUENCE
[int]
size 100000
std::sort 0.021876
std::stable_sort 0.087993
timsort 0.008042
[std::string]
size 100000
std::sort 0.402458
std::stable_sort 2.436326
timsort 0.298639
Example bench_merge output (timing scale: milliseconds; omitted detailed results for different
middle iterator positions, reformatted to improve readability):
c++ -v
Using built-in specs.
...
Target: x86_64-pc-linux-gnu
...
gcc version 10.2.0 (GCC)
c++ -I ../include -Wall -Wextra -g -DNDEBUG -O2 -std=c++11 bench_merge.cpp -o bench_merge
./bench_merge
size 100000
element type\algorithm: std::inplace_merge timmerge
RANDOMIZED SEQUENCE
[int] approx. average 33.404430 37.047990
[std::string] approx. average 324.964249 210.297207
REVERSED SEQUENCE
[int] approx. average 11.441404 4.017482
[std::string] approx. average 305.649503 114.773898
SORTED SEQUENCE
[int] approx. average 4.291098 0.105571
[std::string] approx. average 158.238114 0.273858
Detailed bench_merge results for different middle iterator positions can be found at
https://github.com/timsort/cpp-TimSort/wiki/Benchmark-results
[cmake]: https://cmake.org/
[conan]: https://conan.io/
[conan-center]: https://conan.io/center
[std-inplace-merge]: https://en.cppreference.com/w/cpp/algorithm/ranges/inplace_merge
[std-sort]: https://en.cppreference.com/w/cpp/algorithm/ranges/sort
[std-stable-sort]: https://en.cppreference.com/w/cpp/algorithm/ranges/stable_sort