Merge pull request #173 from Morwenn/develop

Release 1.8.1

CMakeLists.txt

@@ -5,7 +5,7 @@ cmake_minimum_required(VERSION 3.8.0)
 
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 
-project(cpp-sort VERSION 1.8.0 LANGUAGES CXX)
+project(cpp-sort VERSION 1.8.1 LANGUAGES CXX)
 
 include(CMakePackageConfigHelpers)
 include(GNUInstallDirs)

README.md

@@ -1,5 +1,5 @@
-[![Latest Release](https://img.shields.io/badge/release-cpp--sort%2F1.8.0-blue.svg)](https://github.com/Morwenn/cpp-sort/releases)
-[![Conan Package](https://img.shields.io/badge/conan-1.8.0-blue.svg)](https://bintray.com/conan/conan-center/cpp-sort%3A_)
+[![Latest Release](https://img.shields.io/badge/release-cpp--sort%2F1.8.1-blue.svg)](https://github.com/Morwenn/cpp-sort/releases/tag/1.8.1)
+[![Conan Package](https://img.shields.io/badge/conan-1.8.1-blue.svg)](https://conan.io/center/cpp-sort?version=1.8.1)
 [![Build Status](https://travis-ci.org/Morwenn/cpp-sort.svg?branch=master)](https://travis-ci.org/Morwenn/cpp-sort)
 [![License](https://img.shields.io/:license-mit-blue.svg)](https://doge.mit-license.org)
 [![Code Coverage](https://codecov.io/gh/Morwenn/cpp-sort/branch/master/graph/badge.svg)](https://codecov.io/gh/Morwenn/cpp-sort)

conanfile.py

@@ -8,7 +8,7 @@
 
 class CppSortConan(ConanFile):
     name = "cpp-sort"
-    version = "1.8.0"
+    version = "1.8.1"
     description = "Additional sorting algorithms & related tools"
     topics = "conan", "cpp-sort", "sorting", "algorithms"
     url = "https://github.com/Morwenn/cpp-sort"

docs/Sorters.md

@@ -228,11 +228,12 @@ Implements a flavour of [QuickMergeSort](https://arxiv.org/abs/1307.3033).
 | Best        | Average     | Worst       | Memory      | Stable      | Iterators     |
 | ----------- | ----------- | ----------- | ----------- | ----------- | ------------- |
 | n           | n log n     | n log n     | log n       | No          | Random-access |
-| n           | n log n     | n log n     | log² n      | No          | Forward       |
+| n           | n log n     | n log n     | log² n      | No          | Bidirectional |
+| n           | n log² n    | n log² n    | log² n      | No          | Forward       |
 
 QuickMergeSort is an algorithm that performs a quicksort-like partition and tries to use mergesort on the bigger partition, using the smaller one as a swap buffer used for the merge operation when possible. The flavour of QuickMergeSort used by `quick_merge_sorter` actually uses an equivalent of [`std::nth_element`](https://en.cppreference.com/w/cpp/algorithm/nth_element) to partition the collection in 1/3-2/3 parts in order to maximize the size of the partition (2 thirds of the space) that can be merge-sorted using the other partition as a swap buffer.
 
-The log n memory is due to top-down mergesort stack recursion in the random-access version, while the memory of the forward version use is dominated by the mutually recursive [introselect](https://en.wikipedia.org/wiki/Introselect) algorithm which is used to implement an `nth_element` equivalent for forward iterators.
+The change in time complexity for forward iterators is due to the partitioning algorithm being O(n log n) instead of O(n). The log n memory is due to top-down mergesort stack recursion in the random-access version, while the memory of the forward version use is dominated by the mutually recursive [introselect](https://en.wikipedia.org/wiki/Introselect) algorithm which is used to implement an `nth_element` equivalent for forward iterators.
 
 This sorter can't throw `std::bad_alloc`.
 
@@ -248,13 +249,14 @@ Implements a [quicksort](https://en.wikipedia.org/wiki/Quicksort).
 
 | Best        | Average     | Worst       | Memory      | Stable      | Iterators     |
 | ----------- | ----------- | ----------- | ----------- | ----------- | ------------- |
-| n           | n log n     | n log n     | log² n      | No          | Forward       |
+| n           | n log n     | n log n     | log² n      | No          | Bidirectional |
+| n           | n log² n    | n log² n    | log² n      | No          | Forward       |
 
 Despite the name, this sorter actually implements some flavour of introsort: if quicksort performs more than 2*log(n) steps, it falls back to a [median-of-medians](https://en.wikipedia.org/wiki/Median_of_medians) pivot selection instead of the usual median-of-9 one. The median-of-medians selection being mutually recursive with an introselect algorithm explains the use of log²n stack memory.
 
 This sorter can't throw `std::bad_alloc`.
 
-*Changed in version 1.2.0:* `quick_sorter` used to run in O(n²), but a fallback to median-of-medians pivot selection was introduced to make it run in O(n log n), the tradeoff being the log²n space used by stack recursion (as opposed to the previous log n one).
+*Changed in version 1.2.0:* `quick_sorter` used to run in O(n²), but a fallback to median-of-medians pivot selection was introduced to make it run in O(n log n) or O(n log² n) depending of the iterator category, the tradeoff being the log² n space used by stack recursion (as opposed to the previous log n one).
 
 ### `selection_sorter`
 

include/cpp-sort/adapters/indirect_adapter.h

@@ -26,6 +26,7 @@
 #include "../detail/iterator_traits.h"
 #include "../detail/memory.h"
 #include "../detail/scope_exit.h"
+#include "../detail/type_traits.h"
 
 namespace cppsort
 {

include/cpp-sort/detail/introselect.h

@@ -250,7 +250,7 @@ namespace detail
             iter_sort3(first, it1, it2, compare, projection);
             iter_sort3(it3, middle, it4, compare, projection);
             iter_sort3(it5, it6, last_1, compare, projection);
-            auto median_it = iter_sort3(it1, middle, it4, std::move(compare), std::move(projection));
+            auto median_it = iter_sort3(it1, middle, it6, std::move(compare), std::move(projection));
             return std::make_pair(median_it, last_1);
         } else {
             auto last_1 = last_it(first, last, size);

include/cpp-sort/detail/poplar_sort.h

@@ -133,7 +133,9 @@ namespace detail
         if (size < 2) return;
 
         std::vector<poplar<RandomAccessIterator>> poplars;
-        poplars.reserve(log2(size));
+        // Harvey & Zatloukal, The Post-Order Heap:
+        // [...] the number of trees, k, is at most floor(lg(n + 1)) + 1
+        poplars.reserve(log2(size + 1) + 1);
 
         //
         // Size of the biggest poplar in the array, which always is a number

include/cpp-sort/detail/recmerge_bidirectional.h

@@ -26,7 +26,6 @@
 #include "iterator_traits.h"
 #include "lower_bound.h"
 #include "rotate.h"
-#include "type_traits.h"
 #include "upper_bound.h"
 
 namespace cppsort

include/cpp-sort/detail/timsort.h

@@ -189,7 +189,7 @@ namespace detail
             CPPSORT_ASSERT(n >= 0);
 
             difference_type r = 0;
-            while (n >= min_merge) {
+            while (n >= 2 * min_merge) {
                 r |= (n & 1);
                 n >>= 1;
             }

include/cpp-sort/detail/vergesort.h

@@ -54,6 +54,7 @@ namespace detail
 
         // Pair of iterators to iterate through the collection
         auto next = is_sorted_until(first, last, compare, projection);
+        if (next == last) return;
         auto current = std::prev(next);
 
         while (true) {

include/cpp-sort/sorters/quick_merge_sorter.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018 Morwenn
+ * Copyright (c) 2018-2020 Morwenn
  * SPDX-License-Identifier: MIT
  */
 #ifndef CPPSORT_SORTERS_QUICK_MERGE_SORTER_H_
@@ -82,7 +82,7 @@ namespace cppsort
             ////////////////////////////////////////////////////////////
             // Sorter traits
 
-            using iterator_category = std::random_access_iterator_tag;
+            using iterator_category = std::forward_iterator_tag;
             using is_always_stable = std::false_type;
         };
     }

include/cpp-sort/version.h

@@ -9,6 +9,6 @@
 
 #define CPPSORT_VERSION_MAJOR 1
 #define CPPSORT_VERSION_MINOR 8
-#define CPPSORT_VERSION_PATCH 0
+#define CPPSORT_VERSION_PATCH 1
 
 #endif // CPPSORT_VERSION_H_

testsuite/CMakeLists.txt

@@ -19,7 +19,7 @@ else()
     message(STATUS "Catch2 not found")
     download_project(PROJ Catch2
                      GIT_REPOSITORY https://github.com/catchorg/Catch2
-                     GIT_TAG master
+                     GIT_TAG v2.13.2
                      UPDATE_DISCONNECTED 1
     )
     add_subdirectory(${Catch2_SOURCE_DIR} ${Catch2_BINARY_DIR})

tools/release-checklist.md

@@ -0,0 +1,36 @@
+List of actions to perform when releasing a new cpp-sort version.
+
+### During the development
+
+The following things need be done prior to the release if they didn't happen during the main
+development phase:
+- [ ] Update the documentation.
+- [ ] Update the releases notes.
+- [ ] Keep track of the things that will be changed in 2.0.0.
+
+### Before the release
+
+- [ ] Check that all issues linked to the milestone are closed.
+- [ ] Check `NOTICE.txt` and `README.md` conformance for stolen code.
+- [ ] Make sure that tests pass and examples build.
+- [ ] Regenerate the benchmarks.
+- [ ] Replace occurences of the version number:
+  - [ ] CMakeLists.txt
+  - [ ] conanfile.py
+  - [ ] README.md
+  - [ ] version.h
+- [ ] Find a name for the new version.
+- [ ] Open a merge request, let the CI do its job.
+- [ ] Merge `develop` into `master`.
+- [ ] Publish the release, don't forget to target `master`.
+
+### After the release
+
+- [ ] Add the Zenodo badge to the release notes.
+- [ ] Close the new version's milestone.
+- [ ] Push the new version to Bincrafters.
+- [ ] Add the new version to Conan Center Index.
+- [ ] Brag about it where relevant.
+- [ ] Merge master into 2.0.0-develop branch.
+- [ ] Fix merge issues.
+- [ ] Improve as needed with C++17 and C++20 features.