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Better 'is_permutation' implementation, tests

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[SVN r84389]
This commit is contained in:
Marshall Clow
2013-05-20 15:37:50 +00:00
parent a4b907197e
commit b9d89c559b
5 changed files with 414 additions and 341 deletions
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157
include/boost/algorithm/cxx11/is_permutation.hpp
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@ -24,10 +24,6 @@
namespace boost { namespace algorithm {
#if __cplusplus >= 201103L
// Use the C++11 versions of is_permutation if it is available
using std::is_permutation; // Section 25.2.12
#else
/// \cond DOXYGEN_HIDE
namespace detail {
template <typename Predicate, typename Iterator>
@ -37,18 +33,82 @@ namespace detail {
template <typename T1>
bool operator () ( const T1 &t1 ) const { return p_ ( *it_, t1 ); }
private:
Predicate &p_;
Predicate p_;
Iterator it_;
};
// Preconditions:
// 1. The sequences are the same length
// 2. Any common elements on the front have been removed (not necessary for correctness, just for performance)
template< class ForwardIterator1, class ForwardIterator2, class BinaryPredicate >
bool is_permutation_inner ( ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2,
BinaryPredicate p ) {
// for each unique value in the sequence [first1,last1), count how many times
// it occurs, and make sure it occurs the same number of times in [first2, last2)
for ( ForwardIterator1 iter = first1; iter != last1; ++iter ) {
value_predicate<BinaryPredicate, ForwardIterator1> pred ( p, iter );
/* For each value we haven't seen yet... */
if ( std::find_if ( first1, iter, pred ) == iter ) {
std::size_t dest_count = std::count_if ( first2, last2, pred );
if ( dest_count == 0 || dest_count != (std::size_t) std::count_if ( iter, last1, pred ))
return false;
}
}
return true;
}
template< class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
bool is_permutation_tag ( ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2,
BinaryPredicate p,
std::forward_iterator_tag, std::forward_iterator_tag ) {
// Skip the common prefix (if any)
while ( first1 != last1 && first2 != last2 && p ( *first1, *first2 )) {
++first1;
++first2;
}
if ( first1 != last1 && first2 != last2 )
return boost::algorithm::detail::is_permutation_inner ( first1, last1, first2, last2,
std::equal_to<typename std::iterator_traits<ForwardIterator1>::value_type> ());
return first1 == last1 && first2 == last2;
}
template <class RandomAccessIterator1, class RandomAccessIterator2, class BinaryPredicate>
bool is_permutation_tag ( RandomAccessIterator1 first1, RandomAccessIterator1 last1,
RandomAccessIterator2 first2, RandomAccessIterator2 last2,
BinaryPredicate p,
std::random_access_iterator_tag, std::random_access_iterator_tag ) {
// Cheap check
if ( std::distance ( first1, last1 ) != std::distance ( first2, last2 ))
return false;
// Skip the common prefix (if any)
while ( first1 != last1 && first2 != last2 && p ( *first1, *first2 )) {
++first1;
++first2;
}
if ( first1 != last1 && first2 != last2 )
return is_permutation_inner (first1, last1, first2, last2, p);
return first1 == last1 && first2 == last2;
}
}
/// \endcond
#if __cplusplus >= 201103L
// Use the C++11 versions of is_permutation if it is available
using std::is_permutation; // Section 25.2.12
#else
/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 first2, BinaryPredicate p )
/// \brief Tests to see if the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param first The start of the input sequence
/// \param last One past the end of the input sequence
/// \param first1 The start of the input sequence
/// \param last1 One past the end of the input sequence
/// \param first2 The start of the second sequence
/// \param p The predicate to compare elements with
///
@ -67,19 +127,7 @@ bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1,
// Create last2
ForwardIterator2 last2 = first2;
std::advance ( last2, std::distance (first1, last1));
// for each unique value in the sequence [first1,last1), count how many times
// it occurs, and make sure it occurs the same number of times in [first2, last2)
for ( ForwardIterator1 iter = first1; iter != last1; ++iter ) {
detail::value_predicate<BinaryPredicate, ForwardIterator1> pred ( p, iter );
/* For each value we haven't seen yet... */
if ( std::find_if ( first1, iter, pred ) == iter ) {
std::size_t dest_count = std::count_if ( first2, last2, pred );
if ( dest_count == 0 || dest_count != (std::size_t) std::count_if ( iter, last1, pred ))
return false;
}
}
return boost::algorithm::detail::is_permutation_inner ( first1, last1, first2, last2, p );
}
return true;
@ -88,23 +136,84 @@ bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1,
/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 first2 )
/// \brief Tests to see if the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param first The start of the input sequence
/// \param last One past the end of the input sequence
/// \param first1 The start of the input sequence
/// \param last2 One past the end of the input sequence
/// \param first2 The start of the second sequence
/// \note This function is part of the C++2011 standard library.
/// We will use the standard one if it is available,
/// otherwise we have our own implementation.
template< class ForwardIterator1, class ForwardIterator2 >
bool is_permutation ( ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 first2 )
bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2 )
{
// How should I deal with the idea that ForwardIterator1::value_type
// and ForwardIterator2::value_type could be different? Define my own comparison predicate?
return boost::algorithm::is_permutation ( first, last, first2,
// Skip the common prefix (if any)
std::pair<ForwardIterator1, ForwardIterator2> eq = std::mismatch (first1, last1, first2 );
first1 = eq.first;
first2 = eq.second;
if ( first1 != last1 ) {
// Create last2
ForwardIterator2 last2 = first2;
std::advance ( last2, std::distance (first1, last1));
return boost::algorithm::detail::is_permutation_inner ( first1, last1, first2, last2,
std::equal_to<typename std::iterator_traits<ForwardIterator1>::value_type> ());
}
return true;
}
#endif
/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last,
/// ForwardIterator2 first2, ForwardIterator2 last2 )
/// \brief Tests to see if the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param first1 The start of the input sequence
/// \param last2 One past the end of the input sequence
/// \param first2 The start of the second sequence
/// \param last1 One past the end of the second sequence
/// \note This function is part of the C++2011 standard library.
/// We will use the standard one if it is available,
/// otherwise we have our own implementation.
template< class ForwardIterator1, class ForwardIterator2 >
bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2 )
{
// How should I deal with the idea that ForwardIterator1::value_type
// and ForwardIterator2::value_type could be different? Define my own comparison predicate?
return boost::algorithm::detail::is_permutation_tag (
first1, last1, first2, last2,
std::equal_to<typename std::iterator_traits<ForwardIterator1>::value_type> (),
typename std::iterator_traits<ForwardIterator1>::iterator_category (),
typename std::iterator_traits<ForwardIterator2>::iterator_category ());
}
/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last,
/// ForwardIterator2 first2, ForwardIterator2 last2,
/// BinaryPredicate p )
/// \brief Tests to see if the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param first1 The start of the input sequence
/// \param last1 One past the end of the input sequence
/// \param first2 The start of the second sequence
/// \param last2 One past the end of the second sequence
/// \param pred The predicate to compare elements with
///
/// \note This function is part of the C++2011 standard library.
/// We will use the standard one if it is available,
/// otherwise we have our own implementation.
template< class ForwardIterator1, class ForwardIterator2, class BinaryPredicate >
bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2,
BinaryPredicate pred )
{
return boost::algorithm::detail::is_permutation_tag (
first1, last1, first2, last2, pred,
typename std::iterator_traits<ForwardIterator1>::iterator_category (),
typename std::iterator_traits<ForwardIterator2>::iterator_category ());
}
/// \fn is_permutation ( const Range &r, ForwardIterator first2 )
/// \brief Tests to see if the sequence [first,last) is a permutation of the sequence starting at first2
///

130
include/boost/algorithm/cxx14/is_permutation.hpp
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@ -1,130 +0,0 @@
/*
Copyright (c) Marshall Clow 2013
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)
*/
/// \file equal.hpp
/// \brief Determines if one
/// \author Marshall Clow
#ifndef BOOST_ALGORITHM_IS_PERMUTATION_HPP
#define BOOST_ALGORITHM_IS_PERMUTATION_HPP
#include <algorithm>
#include <functional> // for std::equal_to
namespace boost { namespace algorithm {
namespace detail {
template <class T1, class T2>
struct is_perm_eq : public std::binary_function<T1, T2, bool> {
bool operator () ( const T1& v1, const T2& v2 ) const { return v1 == v2 ;}
};
template <class RandomAccessIterator1, class RandomAccessIterator2, class BinaryPredicate>
bool is_permutation ( RandomAccessIterator1 first1, RandomAccessIterator1 last1,
RandomAccessIterator2 first2, RandomAccessIterator2 last2, BinaryPredicate pred,
std::random_access_iterator_tag, std::random_access_iterator_tag )
{
// Random-access iterators let is check the sizes in constant time
if ( std::distance ( first1, last1 ) != std::distance ( first2, last2 ))
return false;
// If we know that the sequences are the same size, the original version is fine
return std::is_permutation ( first1, last1, first2, pred );
}
template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
bool is_permutation (
ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2,
BinaryPredicate pred,
std::forward_iterator_tag, std::forward_iterator_tag )
{
// Look for common prefix
for (; first1 != last1 && first2 != last2; ++first1, ++first2)
if (!pred(*first1, *first2))
goto not_done;
// We've reached the end of one of the sequences without a mismatch.
return first1 == last1 && first2 == last2;
not_done:
// Check and make sure that we have the same # of elements left
typedef typename std::iterator_traits<ForwardIterator1>::difference_type diff1_t;
diff1_t len1 = _VSTD::distance(first1, last1);
typedef typename std::iterator_traits<ForwardIterator2>::difference_type diff2_t;
diff2_t len2 = _VSTD::distance(first2, last2);
if (len1 != len2)
return false;
// For each element in [f1, l1) see if there are the
// same number of equal elements in [f2, l2)
for ( ForwardIterator1 i = first1; i != last1; ++i )
{
// Have we already counted this value?
ForwardIterator1 j;
for ( j = first1; j != i; ++j )
if (pred(*j, *i))
break;
if ( j == i ) // didn't find it...
{
// Count number of *i in [f2, l2)
diff1_t c2 = 0;
for ( ForwardIterator2 iter2 = first2; iter2 != last2; ++iter2 )
if (pred(*i, *iter2))
++c2;
if (c2 == 0)
return false;
// Count number of *i in [i, l1)
diff1_t c1 = 0;
for (_ForwardIterator1 iter1 = i; iter1 != last1; ++iter1 )
if (pred(*i, *iter1))
++c1;
if (c1 != c2)
return false;
}
}
return true;
}
}
template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
bool is_permutation (
ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2,
BinaryPredicate pred )
{
return boost::algorithm::detail::is_permutation (
first1, last1, first2, last2, pred,
typename std::iterator_traits<ForwardIterator1>::iterator_category (),
typename std::iterator_traits<ForwardIterator2>::iterator_category ());
}
template<class ForwardIterator1, class ForwardIterator2>
bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2 )
{
typedef typename iterator_traits<_ForwardIterator1>::value_type value1_t;
typedef typename iterator_traits<_ForwardIterator2>::value_type value2_t;
return boost::algorithm::detail::is_permutation (
first1, last1, first2, last2,
boost::algorithm::detail::is_perm_eq<
typename std::iterator_traits<InputIterator1>::value_type,
typename std::iterator_traits<InputIterator2>::value_type> (),
typename std::iterator_traits<ForwardIterator1>::iterator_category (),
typename std::iterator_traits<ForwardIterator2>::iterator_category ());
}
// There are already range-based versions of these.
}} // namespace boost and algorithm
#endif // BOOST_ALGORITHM_IS_PERMUTATION_HPP

3
test/equal_test.cpp
View File

@ -91,6 +91,9 @@ void test_equal ()
BOOST_CHECK (!ba::equal ( input_iterator<int *>(num), input_iterator<int *>(num + sz),
input_iterator<int *>(num), input_iterator<int *>(num + sz),
never_eq<int> ));
BOOST_CHECK ( ba::equal ( input_iterator<int *>(num), input_iterator<int *>(num + sz),
random_access_iterator<int *>(num), random_access_iterator<int *>(num + sz),
eq<int> ));
// different sequences are different
BOOST_CHECK (!ba::equal ( input_iterator<int *>(num + 1), input_iterator<int *>(num + sz),

87
test/is_permutation_test1.cpp
View File

@ -19,10 +19,95 @@
#include <vector>
#include <list>
#include "iterator_test.hpp"
template <typename T>
bool eq ( const T& a, const T& b ) { return a == b; }
template <typename T>
bool never_eq ( const T&, const T& ) { return false; }
namespace ba = boost::algorithm;
// namespace ba = boost;
void test_sequence1 () {
int num[] = { 1, 1, 2, 3, 5 };
const int sz = sizeof (num)/sizeof(num[0]);
// Empty sequences
BOOST_CHECK (
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num),
forward_iterator<int *>(num)));
BOOST_CHECK (
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num),
forward_iterator<int *>(num), forward_iterator<int *>(num)));
BOOST_CHECK (
ba::is_permutation (
random_access_iterator<int *>(num), random_access_iterator<int *>(num),
random_access_iterator<int *>(num), random_access_iterator<int *>(num)));
BOOST_CHECK (
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num),
forward_iterator<int *>(num),
never_eq<int> )); // Since the sequences are empty, the pred is never called
// Empty vs. non-empty
BOOST_CHECK ( !
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num),
forward_iterator<int *>(num), forward_iterator<int *>(num + 1)));
BOOST_CHECK ( !
ba::is_permutation (
forward_iterator<int *>(num + 1), forward_iterator<int *>(num + 2),
forward_iterator<int *>(num), forward_iterator<int *>(num)));
BOOST_CHECK ( !
ba::is_permutation (
random_access_iterator<int *>(num + 1), random_access_iterator<int *>(num + 2),
random_access_iterator<int *>(num), random_access_iterator<int *>(num)));
BOOST_CHECK ( !
ba::is_permutation (
random_access_iterator<int *>(num), random_access_iterator<int *>(num),
random_access_iterator<int *>(num + 1), random_access_iterator<int *>(num + 2)));
// Something should be a permutation of itself
BOOST_CHECK (
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num + sz),
forward_iterator<int *>(num)));
BOOST_CHECK (
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num + sz),
forward_iterator<int *>(num), eq<int> ));
BOOST_CHECK (
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num + sz),
forward_iterator<int *>(num), forward_iterator<int *>(num + sz )));
BOOST_CHECK (
ba::is_permutation (
forward_iterator<int *>(num), forward_iterator<int *>(num + sz),
forward_iterator<int *>(num), forward_iterator<int *>(num + sz ),
eq<int> ));
BOOST_CHECK (
ba::is_permutation (
random_access_iterator<int *>(num), random_access_iterator<int *>(num + sz),
random_access_iterator<int *>(num), random_access_iterator<int *>(num + sz)));
BOOST_CHECK (
ba::is_permutation (
random_access_iterator<int *>(num), random_access_iterator<int *>(num + sz),
random_access_iterator<int *>(num), random_access_iterator<int *>(num + sz),
eq<int> ));
BOOST_CHECK (
ba::is_permutation (
random_access_iterator<int *>(num), random_access_iterator<int *>(num + sz),
forward_iterator<int *>(num), forward_iterator<int *>(num + sz),
eq<int> ));
std::vector<int> v, v1;
v.clear ();

8
test/mismatch_test.cpp
View File

@ -24,7 +24,7 @@ bool never_eq ( const T&, const T& ) { return false; }
namespace ba = boost::algorithm;
template <typename Iter1, typename Iter2>
bool iter_eq ( std::pair<Iter1, Iter1> pr, Iter1 first, Iter2 second ) {
bool iter_eq ( std::pair<Iter1, Iter2> pr, Iter1 first, Iter2 second ) {
return pr.first == first && pr.second == second;
}
@ -141,6 +141,12 @@ void test_mismatch ()
never_eq<int> ),
input_iterator<int *>(num), input_iterator<int *>(num)));
BOOST_CHECK ( iter_eq (
ba::mismatch ( input_iterator<int *>(num), input_iterator<int *>(num + sz),
random_access_iterator<int *>(num), random_access_iterator<int *>(num + sz),
never_eq<int> ),
input_iterator<int *>(num), random_access_iterator<int *>(num)));
// different sequences are different
BOOST_CHECK ( iter_eq (
ba::mismatch ( input_iterator<int *>(num + 1), input_iterator<int *>(num + sz),