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/* Sorting objects for which copies cost more than swaps. -*- C++ -*-
Copyright (C) 2001-2010 Roberto Bagnara <bagnara@cs.unipr.it>
Copyright (C) 2010-2011 BUGSENG srl (http://bugseng.com)
This file is part of the Parma Polyhedra Library (PPL).
The PPL is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
The PPL is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1307, USA.
For the most up-to-date information see the Parma Polyhedra Library
site: http://www.cs.unipr.it/ppl/ . */
#ifndef PPL_swapping_sort_icc
#define PPL_swapping_sort_icc 1
#include <vector>
#include <algorithm>
namespace {
template <typename RA_Container, typename Compare>
struct Indirect_Sort_Compare {
typedef typename RA_Container::size_type size_type;
Indirect_Sort_Compare(const RA_Container& cont,
size_type base = 0,
Compare comp = Compare())
: container(cont), base_index(base), compare(comp) {
}
bool operator()(size_type i, size_type j) const {
return compare(container[base_index + i], container[base_index + j]);
}
const RA_Container& container;
const size_type base_index;
const Compare compare;
}; // struct Indirect_Sort_Compare
template <typename RA_Container>
struct Indirect_Unique_Compare {
typedef typename RA_Container::size_type size_type;
Indirect_Unique_Compare(const RA_Container& cont, size_type base = 0)
: container(cont), base_index(base) {
}
bool operator()(size_type i, size_type j) const {
return container[base_index + i] == container[base_index + j];
}
const RA_Container& container;
const size_type base_index;
}; // struct Indirect_Unique_Compare
template <typename RA_Container>
struct Indirect_Swapper {
typedef typename RA_Container::size_type size_type;
Indirect_Swapper(RA_Container& cont, size_type base = 0)
: container(cont), base_index(base) {
}
void operator()(size_type i, size_type j) const {
std::swap(container[base_index + i], container[base_index + j]);
}
RA_Container& container;
const size_type base_index;
}; // struct Indirect_Swapper
template <typename RA_Container1, typename RA_Container2>
struct Indirect_Swapper2 {
typedef typename RA_Container1::size_type size_type;
Indirect_Swapper2(RA_Container1& cont1, RA_Container2& cont2)
: container1(cont1), container2(cont2) {
}
void operator()(size_type i, size_type j) const {
std::swap(container1[i], container1[j]);
std::swap(container2[i], container2[j]);
}
RA_Container1& container1;
RA_Container2& container2;
}; // struct Indirect_Swapper2
template <typename Sort_Comparer, typename Unique_Comparer, typename Swapper>
typename Sort_Comparer::size_type
indirect_sort_and_unique(typename Sort_Comparer::size_type num_elems,
Sort_Comparer sort_cmp,
Unique_Comparer unique_cmp,
Swapper indirect_swap) {
typedef typename Sort_Comparer::size_type index_type;
// `iv' is a vector of indices for the portion of rows to be sorted.
PPL_ASSERT(num_elems >= 2);
std::vector<index_type> iv;
iv.reserve(num_elems);
for (index_type i = 0, i_end = num_elems; i != i_end; ++i)
iv.push_back(i);
typedef typename std::vector<index_type>::iterator Iter;
const Iter iv_begin = iv.begin();
Iter iv_end = iv.end();
// Sort `iv' by comparing the rows indexed by its elements.
std::sort(iv_begin, iv_end, sort_cmp);
// Swap the indexed rows according to `iv':
// for each index `i', the element that should be placed in
// position dst = i is the one placed in position src = iv[i].
for (index_type i = num_elems; i-- > 0; ) {
if (i != iv[i]) {
index_type dst = i;
index_type src = iv[i];
do {
indirect_swap(src, dst);
iv[dst] = dst;
dst = src;
src = iv[dst];
} while (i != src);
iv[dst] = dst;
}
}
// Restore `iv' indices to 0 .. num_elems-1 for the call to unique.
for (index_type i = num_elems; i-- > 0; )
iv[i] = i;
// Unique `iv' by comparing the rows indexed by its elements.
iv_end = std::unique(iv_begin, iv_end, unique_cmp);
const index_type num_sorted = iv_end - iv_begin;
const index_type num_duplicates = num_elems - num_sorted;
if (num_duplicates == 0)
return 0;
// There were duplicates: swap the rows according to `iv'.
index_type dst = 0;
while (dst < num_sorted && dst == iv[dst])
++dst;
if (dst == num_sorted)
return num_duplicates;
do {
const index_type src = iv[dst];
indirect_swap(src, dst);
++dst;
}
while (dst < num_sorted);
return num_duplicates;
}
} // namespace
#endif // !defined(PPL_swapping_sort_icc)
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