boost/sort/spreadsort/string_sort.hpp
//Templated hybrid string_sort // Copyright Steven J. Ross 2001 - 2009. // Distributed under the Boost Software License, Version 1.0. // (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // See http://www.boost.org/libs/sort/ for library home page. /* Some improvements suggested by: Phil Endecott and Frank Gennari */ #ifndef BOOST_STRING_SORT_HPP #define BOOST_STRING_SORT_HPP #include <algorithm> #include <vector> #include <cstring> #include <limits> #include <boost/static_assert.hpp> #include <boost/sort/spreadsort/detail/constants.hpp> #include <boost/sort/spreadsort/detail/string_sort.hpp> namespace boost { namespace sort { namespace spreadsort { /*! \brief String sort algorithm using random access iterators, allowing character-type overloads.\n (All variants fall back to @c std::sort if the data size is too small, < @c detail::min_sort_size). \details @c string_sort is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than @c std::sort for large tests (>=100kB).\n \par Worst-case performance is <em> O(N * (lg(range)/s + s)) </em>, so @c integer_sort is asymptotically faster than pure comparison-based algorithms. @c s is @c max_splits, which defaults to 11, so its worst-case with default settings for 32-bit integers is <em> O(N * ((32/11) </em> slow radix-based iterations fast comparison-based iterations).\n\n Some performance plots of runtime vs. n and log(range) are provided:\n <a href="../../doc/graph/windows_string_sort.htm"> windows_string_sort</a>\n <a href="../../doc/graph/osx_string_sort.htm"> osx_string_sort</a> \tparam RandomAccessIter <a href="http://www.cplusplus.com/reference/iterator/RandomAccessIterator/">Random access iterator</a> \tparam Unsigned_char_type Unsigned character type used for string. \param[in] first Iterator pointer to first element. \param[in] last Iterator pointing to one beyond the end of data. \param[in] unused value with the same type as the result of the [] operator, defining the Unsigned_char_type. The actual value is unused. \pre [@c first, @c last) is a valid range. \pre @c RandomAccessIter @c value_type is mutable. \pre @c RandomAccessIter @c value_type is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable">LessThanComparable</a> \pre @c RandomAccessIter @c value_type supports the @c operator>>, which returns an integer-type right-shifted a specified number of bits. \post The elements in the range [@c first, @c last) are sorted in ascending order. \throws std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw. \warning Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. \warning Invalid arguments cause undefined behaviour. \note @c spreadsort function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming. \remark The lesser of <em> O(N*log(N)) </em> comparisons and <em> O(N*log(K/S + S)) </em>operations worst-case, where: \remark * N is @c last - @c first, \remark * K is the log of the range in bits (32 for 32-bit integers using their full range), \remark * S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). */ template <class RandomAccessIter, class Unsigned_char_type> inline void string_sort(RandomAccessIter first, RandomAccessIter last, Unsigned_char_type unused) { //Don't sort if it's too small to optimize if (last - first < detail::min_sort_size) std::sort(first, last); else detail::string_sort(first, last, unused); } /*! \brief String sort algorithm using random access iterators, wraps using default of unsigned char. (All variants fall back to @c std::sort if the data size is too small, < @c detail::min_sort_size). \details @c string_sort is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than @c std::sort for large tests (>=100kB).\n Worst-case performance is <em> O(N * (lg(range)/s + s)) </em>, so @c integer_sort is asymptotically faster than pure comparison-based algorithms. @c s is @c max_splits, which defaults to 11, so its worst-case with default settings for 32-bit integers is <em> O(N * ((32/11) </em> slow radix-based iterations fast comparison-based iterations).\n\n Some performance plots of runtime vs. n and log(range) are provided:\n <a href="../../doc/graph/windows_string_sort.htm"> windows_string_sort</a> \n <a href="../../doc/graph/osx_string_sort.htm"> osx_string_sort</a> \param[in] first Iterator pointer to first element. \param[in] last Iterator pointing to one beyond the end of data. \pre [@c first, @c last) is a valid range. \pre @c RandomAccessIter @c value_type is mutable. \pre @c RandomAccessIter @c value_type is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable">LessThanComparable</a> \pre @c RandomAccessIter @c value_type supports the @c operator>>, which returns an integer-type right-shifted a specified number of bits. \post The elements in the range [@c first, @c last) are sorted in ascending order. \throws std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw. \warning Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. \warning Invalid arguments cause undefined behaviour. \note @c spreadsort function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming. \remark The lesser of <em> O(N*log(N)) </em> comparisons and <em> O(N*log(K/S + S)) </em>operations worst-case, where: \remark * N is @c last - @c first, \remark * K is the log of the range in bits (32 for 32-bit integers using their full range), \remark * S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). */ template <class RandomAccessIter> inline void string_sort(RandomAccessIter first, RandomAccessIter last) { unsigned char unused = '\0'; string_sort(first, last, unused); } /*! \brief String sort algorithm using random access iterators, allowing character-type overloads. (All variants fall back to @c std::sort if the data size is too small, < detail::min_sort_size). \details @c integer_sort is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than @c std::sort for large tests (>=100kB).\n Worst-case performance is <em> O(N * (lg(range)/s + s)) </em>, so @c integer_sort is asymptotically faster than pure comparison-based algorithms. @c s is @c max_splits, which defaults to 11, so its worst-case with default settings for 32-bit integers is <em> O(N * ((32/11) </em> slow radix-based iterations fast comparison-based iterations).\n\n Some performance plots of runtime vs. n and log(range) are provided:\n <a href="../../doc/graph/windows_integer_sort.htm"> windows_integer_sort</a> \n <a href="../../doc/graph/osx_integer_sort.htm"> osx_integer_sort</a> \tparam RandomAccessIter <a href="http://www.cplusplus.com/reference/iterator/RandomAccessIterator/">Random access iterator</a> \tparam Comp Functor type to use for comparison. \tparam Unsigned_char_type Unsigned character type used for string. \param[in] first Iterator pointer to first element. \param[in] last Iterator pointing to one beyond the end of data. \param[in] comp A binary functor that returns whether the first element passed to it should go before the second in order. \param[in] unused value with the same type as the result of the [] operator, defining the Unsigned_char_type. The actual value is unused. \pre [@c first, @c last) is a valid range. \pre @c RandomAccessIter @c value_type is mutable. \pre @c RandomAccessIter @c value_type is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable">LessThanComparable</a> \pre @c RandomAccessIter @c value_type supports the @c operator>>, which returns an integer-type right-shifted a specified number of bits. \post The elements in the range [@c first, @c last) are sorted in ascending order. \return @c void. \throws std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw. \warning Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. \warning Invalid arguments cause undefined behaviour. \note @c spreadsort function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming. \remark The lesser of <em> O(N*log(N)) </em> comparisons and <em> O(N*log(K/S + S)) </em>operations worst-case, where: \remark * N is @c last - @c first, \remark * K is the log of the range in bits (32 for 32-bit integers using their full range), \remark * S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). */ template <class RandomAccessIter, class Compare, class Unsigned_char_type> inline void reverse_string_sort(RandomAccessIter first, RandomAccessIter last, Compare comp, Unsigned_char_type unused) { //Don't sort if it's too small to optimize. if (last - first < detail::min_sort_size) std::sort(first, last, comp); else detail::reverse_string_sort(first, last, unused); } /*! \brief String sort algorithm using random access iterators, wraps using default of @c unsigned char. (All variants fall back to @c std::sort if the data size is too small, < @c detail::min_sort_size). \details @c integer_sort is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than @c std::sort for large tests (>=100kB).\n Worst-case performance is <em> O(N * (lg(range)/s + s)) </em>, so @c integer_sort is asymptotically faster than pure comparison-based algorithms. @c s is @c max_splits, which defaults to 11, so its worst-case with default settings for 32-bit integers is <em> O(N * ((32/11) </em> slow radix-based iterations fast comparison-based iterations).\n\n Some performance plots of runtime vs. n and log(range) are provided:\n <a href="../../doc/graph/windows_integer_sort.htm"> windows_integer_sort</a> \n <a href="../../doc/graph/osx_integer_sort.htm"> osx_integer_sort</a> \param[in] first Iterator pointer to first element. \param[in] last Iterator pointing to one beyond the end of data. \param[in] comp A binary functor that returns whether the first element passed to it should go before the second in order. \pre [@c first, @c last) is a valid range. \pre @c RandomAccessIter @c value_type is mutable. \pre @c RandomAccessIter @c value_type is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable">LessThanComparable</a> \pre @c RandomAccessIter @c value_type supports the @c operator>>, which returns an integer-type right-shifted a specified number of bits. \post The elements in the range [@c first, @c last) are sorted in ascending order. \return @c void. \throws std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw. \warning Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. \warning Invalid arguments cause undefined behaviour. \note @c spreadsort function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming. \remark The lesser of <em> O(N*log(N)) </em> comparisons and <em> O(N*log(K/S + S)) </em>operations worst-case, where: \remark * N is @c last - @c first, \remark * K is the log of the range in bits (32 for 32-bit integers using their full range), \remark * S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). */ template <class RandomAccessIter, class Compare> inline void reverse_string_sort(RandomAccessIter first, RandomAccessIter last, Compare comp) { unsigned char unused = '\0'; reverse_string_sort(first, last, comp, unused); } /*! \brief String sort algorithm using random access iterators, wraps using default of @c unsigned char. (All variants fall back to @c std::sort if the data size is too small, < @c detail::min_sort_size). \details @c integer_sort is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than @c std::sort for large tests (>=100kB).\n Worst-case performance is <em> O(N * (lg(range)/s + s)) </em>, so @c integer_sort is asymptotically faster than pure comparison-based algorithms. @c s is @c max_splits, which defaults to 11, so its worst-case with default settings for 32-bit integers is <em> O(N * ((32/11) </em> slow radix-based iterations fast comparison-based iterations).\n\n Some performance plots of runtime vs. n and log(range) are provided:\n <a href="../../doc/graph/windows_integer_sort.htm"> windows_integer_sort</a> \n <a href="../../doc/graph/osx_integer_sort.htm"> osx_integer_sort</a> \param[in] first Iterator pointer to first element. \param[in] last Iterator pointing to one beyond the end of data. \param[in] getchar Bracket functor equivalent to @c operator[], taking a number corresponding to the character offset. \param[in] length Functor to get the length of the string in characters. \pre [@c first, @c last) is a valid range. \pre @c RandomAccessIter @c value_type is mutable. \pre @c RandomAccessIter @c value_type is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable">LessThanComparable</a> \pre @c RandomAccessIter @c value_type supports the @c operator>>, which returns an integer-type right-shifted a specified number of bits. \post The elements in the range [@c first, @c last) are sorted in ascending order. \return @c void. \throws std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw. \warning Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. \warning Invalid arguments cause undefined behaviour. \note @c spreadsort function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming. \remark The lesser of <em> O(N*log(N)) </em> comparisons and <em> O(N*log(K/S + S)) </em>operations worst-case, where: \remark * N is @c last - @c first, \remark * K is the log of the range in bits (32 for 32-bit integers using their full range), \remark * S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). */ template <class RandomAccessIter, class Get_char, class Get_length> inline void string_sort(RandomAccessIter first, RandomAccessIter last, Get_char getchar, Get_length length) { //Don't sort if it's too small to optimize if (last - first < detail::min_sort_size) std::sort(first, last); else { //skipping past empties, which allows us to get the character type //.empty() is not used so as not to require a user declaration of it while (!length(*first)) { if (++first == last) return; } detail::string_sort(first, last, getchar, length, getchar((*first), 0)); } } /*! \brief String sort algorithm using random access iterators, wraps using default of @c unsigned char. (All variants fall back to @c std::sort if the data size is too small, < @c detail::min_sort_size). \details @c integer_sort is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than @c std::sort for large tests (>=100kB).\n Worst-case performance is <em> O(N * (lg(range)/s + s)) </em>, so @c integer_sort is asymptotically faster than pure comparison-based algorithms. @c s is @c max_splits, which defaults to 11, so its worst-case with default settings for 32-bit integers is <em> O(N * ((32/11) </em> slow radix-based iterations fast comparison-based iterations).\n\n Some performance plots of runtime vs. n and log(range) are provided:\n <a href="../../doc/graph/windows_integer_sort.htm"> windows_integer_sort</a> \n <a href="../../doc/graph/osx_integer_sort.htm"> osx_integer_sort</a> \param[in] first Iterator pointer to first element. \param[in] last Iterator pointing to one beyond the end of data. \param[in] getchar Bracket functor equivalent to @c operator[], taking a number corresponding to the character offset. \param[in] length Functor to get the length of the string in characters. \param[in] comp A binary functor that returns whether the first element passed to it should go before the second in order. \pre [@c first, @c last) is a valid range. \pre @c RandomAccessIter @c value_type is mutable. \pre @c RandomAccessIter @c value_type is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable">LessThanComparable</a> \post The elements in the range [@c first, @c last) are sorted in ascending order. \return @c void. \throws std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw. \warning Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. \warning Invalid arguments cause undefined behaviour. \note @c spreadsort function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming. \remark The lesser of <em> O(N*log(N)) </em> comparisons and <em> O(N*log(K/S + S)) </em>operations worst-case, where: \remark * N is @c last - @c first, \remark * K is the log of the range in bits (32 for 32-bit integers using their full range), \remark * S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). */ template <class RandomAccessIter, class Get_char, class Get_length, class Compare> inline void string_sort(RandomAccessIter first, RandomAccessIter last, Get_char getchar, Get_length length, Compare comp) { //Don't sort if it's too small to optimize if (last - first < detail::min_sort_size) std::sort(first, last, comp); else { //skipping past empties, which allows us to get the character type //.empty() is not used so as not to require a user declaration of it while (!length(*first)) { if (++first == last) return; } detail::string_sort(first, last, getchar, length, comp, getchar((*first), 0)); } } /*! \brief Reverse String sort algorithm using random access iterators. (All variants fall back to @c std::sort if the data size is too small, < @c detail::min_sort_size). \details @c integer_sort is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than @c std::sort for large tests (>=100kB).\n Worst-case performance is <em> O(N * (lg(range)/s + s)) </em>, so @c integer_sort is asymptotically faster than pure comparison-based algorithms. @c s is @c max_splits, which defaults to 11, so its worst-case with default settings for 32-bit integers is <em> O(N * ((32/11) </em> slow radix-based iterations fast comparison-based iterations).\n\n Some performance plots of runtime vs. n and log(range) are provided:\n <a href="../../doc/graph/windows_integer_sort.htm"> windows_integer_sort</a> \n <a href="../../doc/graph/osx_integer_sort.htm"> osx_integer_sort</a> \param[in] first Iterator pointer to first element. \param[in] last Iterator pointing to one beyond the end of data. \param[in] getchar Bracket functor equivalent to @c operator[], taking a number corresponding to the character offset. \param[in] length Functor to get the length of the string in characters. \param[in] comp A binary functor that returns whether the first element passed to it should go before the second in order. \pre [@c first, @c last) is a valid range. \pre @c RandomAccessIter @c value_type is mutable. \pre @c RandomAccessIter @c value_type is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable">LessThanComparable</a> \post The elements in the range [@c first, @c last) are sorted in ascending order. \return @c void. \throws std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw. \warning Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. \warning Invalid arguments cause undefined behaviour. \note @c spreadsort function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming. \remark The lesser of <em> O(N*log(N)) </em> comparisons and <em> O(N*log(K/S + S)) </em>operations worst-case, where: \remark * N is @c last - @c first, \remark * K is the log of the range in bits (32 for 32-bit integers using their full range), \remark * S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). */ template <class RandomAccessIter, class Get_char, class Get_length, class Compare> inline void reverse_string_sort(RandomAccessIter first, RandomAccessIter last, Get_char getchar, Get_length length, Compare comp) { //Don't sort if it's too small to optimize if (last - first < detail::min_sort_size) std::sort(first, last, comp); else { //skipping past empties, which allows us to get the character type //.empty() is not used so as not to require a user declaration of it while (!length(*(--last))) { //If there is just one non-empty at the beginning, this is sorted if (first == last) return; } //making last just after the end of the non-empty part of the array detail::reverse_string_sort(first, last + 1, getchar, length, comp, getchar((*last), 0)); } } } } } #endif