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#include "set.h"
#include <unordered_map>
#include <unordered_set>
#include <utility>
namespace erebos {
using std::pair;
using std::unordered_map;
using std::unordered_set;
using std::move;
SetBase::SetBase():
p(make_shared<Priv>())
{
}
SetBase::SetBase(const vector<Ref> & refs)
{
vector<Stored<SetItem>> items;
for (const auto & r : refs)
items.push_back(Stored<SetItem>::load(r));
p = shared_ptr<Priv>(new Priv {
.items = move(items),
});
}
SetBase::SetBase(shared_ptr<const Priv> p_):
p(move(p_))
{
}
shared_ptr<const SetBase::Priv> SetBase::add(Storage & st, const vector<Ref> & refs) const
{
auto item = st.store(SetItem {
.prev = p->items,
.item = refs,
});
return shared_ptr<const Priv>(new Priv {
.items = { move(item) },
});
}
static void gatherSetItems(unordered_set<Digest> & seenSet, unordered_set<Digest> & seenElem,
vector<Ref> & res, const Stored<SetItem> & item)
{
if (!seenElem.insert(item.ref().digest()).second)
return;
for (const auto & r : item->item)
if (seenSet.insert(r.digest()).second)
res.push_back(r);
for (const auto & p : item->prev)
gatherSetItems(seenSet, seenElem, res, p);
}
vector<vector<Ref>> SetBase::toList() const
{
/* Splits the graph starting from all set item refs into connected
* components (partitions), each such partition makes one set item,
* merged together in the templated SetView constructor. */
// Gather all item references
vector<Ref> items;
{
unordered_set<Digest> seenSet, seenElem;
for (const auto & i : p->items)
gatherSetItems(seenSet, seenElem, items, i);
}
unordered_map<Digest, unsigned> partMap; // maps item ref to partition number
vector<unsigned> partMerge; // maps partitions to resulting one after partition merge
// Use (cached) root set for assigning partition numbers
for (const auto & item : items) {
const auto roots = item.roots();
unsigned part = partMerge.size();
// If any root has partition number already, pick the smallest one
for (const auto & rdgst : roots) {
auto it = partMap.find(rdgst);
if (it != partMap.end() && it->second < part)
part = it->second;
}
// Update partition number for the roots and if this item
// merges some partitions, also update the merge info
for (const auto & rdgst : roots) {
auto it = partMap.find(rdgst);
if (it == partMap.end()) {
partMap.emplace(rdgst, part);
} else if (it->second != part) {
partMerge[it->second] = part;
it->second = part;
}
}
// If no existing partition has been touched, mark a new one
if (part == partMerge.size())
partMerge.push_back(part);
// And store resulting partition number
partMap.emplace(item.digest(), part);
}
// Get all the refs for each partition
vector<vector<Ref>> res(partMerge.size());
for (const auto & item : items) {
unsigned part = partMap[item.digest()];
for (unsigned p = partMerge[part]; p != part; p = partMerge[p])
part = p;
res[part].push_back(item);
}
// Remove empty elements (merged partitions) from result list
res.erase(std::remove(res.begin(), res.end(), vector<Ref>()), res.end());
return res;
}
vector<Digest> SetBase::digests() const
{
vector<Digest> res;
res.reserve(p->items.size());
for (const auto & i : p->items)
res.push_back(i.ref().digest());
return res;
}
SetItem SetItem::load(const Ref & ref)
{
if (auto rec = ref->asRecord()) {
vector<Stored<SetItem>> prev;
for (auto p : rec->items("PREV"))
if (const auto & x = p.as<SetItem>())
prev.push_back(*x);
vector<Ref> item;
for (auto i : rec->items("item"))
if (const auto & x = i.asRef())
item.push_back(*x);
return SetItem {
.prev = std::move(prev),
.item = std::move(item),
};
}
return SetItem {
.prev = {},
.item = {},
};
}
Ref SetItem::store(const Storage & st) const
{
vector<Record::Item> items;
for (const auto & p : prev)
items.emplace_back("PREV", p.ref());
for (const auto & r : item)
items.emplace_back("item", r);
return st.storeObject(Record(std::move(items)));
}
}
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