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/*
* Copyright (c) 2015-2017, Intel Corporation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef PARTITIONED_SET_H
#define PARTITIONED_SET_H
#include "container.h"
#include "noncopyable.h"
#include "flat_containers.h"
#include "ue2common.h"
#include <algorithm>
#include <vector>
#include <boost/dynamic_bitset.hpp>
namespace ue2 {
static constexpr size_t INVALID_SUBSET = ~(size_t)0;
/**
* partition_set represents a partitioning of a set of integers [0, n) into
* disjoint non-empty subsets.
*
* The subsets themselves are also indexed by integers.
*
* The underlying integer type for the set members is parameterized.
*/
template<typename T>
class partitioned_set : noncopyable {
public:
class subset {
public:
typedef typename std::vector<T>::const_iterator const_iterator;
size_t size() const {
assert(members.size());
return members.size();
}
const_iterator begin() const {
return members.begin();
}
const_iterator end() const {
return members.end();
}
private:
std::vector<T> members; /**< sorted members of the subset */
friend class partitioned_set;
};
/** returns the number of subsets in the partition */
size_t size() const { return subsets.size(); }
/** returns the subset with the given index */
const subset &operator[](size_t subset_index) const {
assert(subset_index < size());
return subsets[subset_index];
}
/**
* Splits the subset with the given subset_index based on whether its
* members are also members of the splitter set.
*
* The smaller of the intersection and difference is placed into a new
* subset, the index of which is returned. The larger part remains with the
* subset index.
*
* If the set was not split (due to there being no overlap with splitter or
* being a complete subset), INVALID_SUBSET is returned.
*/
size_t split(size_t subset_index, const flat_set<T> &splitter) {
assert(!splitter.empty());
if (splitter.empty()) {
return INVALID_SUBSET;
}
subset &orig = subsets[subset_index];
assert(orig.size());
split_temp_diff.clear();
split_temp_inter.clear();
auto sp_it = splitter.begin();
auto sp_e = splitter.end();
/* subset members are always in sorted order. */
assert(std::is_sorted(orig.members.begin(), orig.members.end()));
if (orig.members.back() < *sp_it) {
/* first splitter is greater than all our members */
return INVALID_SUBSET;
}
if (orig.members.front() > *splitter.rbegin()) {
/* last splitter is less than all our members */
return INVALID_SUBSET;
}
for (auto it = orig.members.begin(); it != orig.members.end(); ++it) {
const auto &member = *it;
assert(member < member_to_subset.size());
sp_it = std::lower_bound(sp_it, sp_e, member);
if (sp_it == sp_e) {
split_temp_diff.insert(split_temp_diff.end(), it,
orig.members.end());
break;
}
if (*sp_it > member) {
split_temp_diff.push_back(member);
} else {
split_temp_inter.push_back(member);
}
}
assert(split_temp_diff.size() + split_temp_inter.size() == orig.size());
if (split_temp_inter.empty()) {
assert(split_temp_diff == orig.members);
return INVALID_SUBSET;
}
if (split_temp_diff.empty()) {
assert(split_temp_inter == orig.members);
return INVALID_SUBSET;
}
assert(MIN(split_temp_inter[0], split_temp_diff[0]) == orig.members[0]);
/* work out which is the bigger half */
std::vector<T> *big;
std::vector<T> *small;
if (split_temp_diff.size() > split_temp_inter.size()) {
big = &split_temp_diff;
small = &split_temp_inter;
} else {
big = &split_temp_inter;
small = &split_temp_diff;
}
/* larger subset replaces the input subset */
std::vector<T> temp_i;
insert(&temp_i, temp_i.end(), *big);
orig.members.swap(temp_i);
/* smaller subset is placed in the new subset */
size_t new_index = subsets.size();
subsets.push_back(subset());
insert(&subsets.back().members, subsets.back().members.end(), *small);
for (const auto &e : *small) {
member_to_subset[e] = new_index;
}
return new_index;
}
/**
* Returns all subsets which have a member in keys.
*/
void find_overlapping(const flat_set<T> &keys,
std::vector<size_t> *containing) const {
boost::dynamic_bitset<> seen(subsets.size()); // all zero by default.
for (const auto &key : keys) {
assert(key < member_to_subset.size());
size_t sub = member_to_subset[key];
assert(sub < subsets.size());
seen.set(sub);
}
for (size_t i = seen.find_first(); i != seen.npos;
i = seen.find_next(i)) {
containing->push_back(i);
}
}
/**
* Creates a partitioned set containing elements [0, state_to_subset.size() )
*
* The initial subset that an element belongs to is given by the
* corresponding entry in state_to_subset. The subsets should be identified
* by a dense range of indices starting from 0.
*/
explicit partitioned_set(const std::vector<size_t> &state_to_subset) {
assert(!state_to_subset.empty());
subsets.reserve(state_to_subset.size());
member_to_subset.resize(state_to_subset.size());
split_temp_inter.reserve(state_to_subset.size());
split_temp_diff.reserve(state_to_subset.size());
size_t subset_count = 0;
for (const auto &sub : state_to_subset) {
assert(sub != INVALID_SUBSET);
ENSURE_AT_LEAST(&subset_count, sub + 1);
}
assert(subset_count <= state_to_subset.size());
subsets.resize(subset_count);
for (size_t i = 0; i < state_to_subset.size(); i++) {
/* ensure that our underlying type is big enough to hold all our
* set members */
assert(i == (size_t)(T)i);
size_t sub = state_to_subset[i];
assert(sub < subsets.size());
member_to_subset[i] = sub;
subsets[sub].members.push_back(i);
}
/* none of the subsets should be empty */
assert(std::all_of(subsets.begin(), subsets.end(),
[](const subset &sub){ return sub.size() > 0; }));
}
private:
std::vector<size_t> member_to_subset;
std::vector<subset> subsets;
std::vector<T> split_temp_inter; /**< used internally by split to hold the
* intersection. */
std::vector<T> split_temp_diff; /**< used internally by split to hold the
* set difference. */
};
} // namespace
#endif
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