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#pragma once
#include "flat_row_eggs.h"
#include "util_basics.h"
#include <util/generic/deque.h>
#include <util/generic/vector.h>
#include <util/generic/ptr.h>
#include <numeric>
namespace NKikimr {
namespace NTable {
class TScreen : public TAtomicRefCount<TScreen> {
public:
struct THole {
explicit THole(bool all)
: Begin(all ? 0 : Max<TRowId>())
{
}
THole(TRowId begin, TRowId end)
: Begin(begin)
, End(end)
{
}
explicit operator bool() const
{
return Begin < End;
}
bool operator==(const THole &hole) const
{
return Begin == hole.Begin && End == hole.End;
}
bool Has(TRowId rowId) const
{
return Begin <= rowId && rowId < End;
}
THole Cut(THole hole) const
{
auto begin = Max(Begin, hole.Begin);
auto end = Min(End, hole.End);
return begin > end ? THole(false) : THole(begin, end);
}
TRowId Begin = 0;
TRowId End = Max<TRowId>();
};
struct TCook {
TDeque<THole> Unwrap() noexcept
{
Pass(Max<TRowId>()); /* will flush current hole */
return std::exchange(Holes, TDeque<THole>{ });
}
void Pass(TRowId ref) noexcept
{
Y_VERIFY(Tail <= ref, "Got page ref from the past");
if (Open != Max<TRowId>() && Tail != ref) {
auto begin = std::exchange(Open, Max<TRowId>());
Holes.emplace_back(begin, Tail);
}
Open = Min(Open, ref);
Tail = ref + 1;
}
private:
TRowId Open = Max<TRowId>();
TRowId Tail = 0;
TDeque<THole> Holes;
};
template<typename TVec>
static TRowId Sum(const TVec &vec) noexcept
{
return
std::accumulate(vec.begin(), vec.end(), TRowId(0),
[](TRowId rows, const THole &hole) {
return rows + (hole.End - hole.Begin);
});
}
using TVec = TVector<THole>;
TScreen(TVec holes) : Holes(std::move(holes)) { }
static THole Iter(const TIntrusiveConstPtr<TScreen> &ref, size_t &on, TRowId rowId, int dir)
{
on = ref ? ref->Lookup(rowId, dir) : Max<size_t>();
return ref ? ref->Hole(on) : THole(true);
}
static THole Next(const TIntrusiveConstPtr<TScreen> &ref, size_t &on, int dir)
{
return ref ? ref->Hole(on += dir) : THole(false);
}
static bool Intersects(const TScreen *scr, THole hole)
{
return bool(hole.Cut(scr ? scr->Bounds() : THole(false)));
}
size_t Size() const noexcept
{
return Holes.size();
}
TVec::const_iterator begin() const
{
return Holes.begin();
}
TVec::const_iterator end() const
{
return Holes.end();
}
bool Cmp(const TScreen &screen) const noexcept
{
return
screen.Size() == Size()
&& std::equal(begin(), end(), screen.begin());
}
size_t Lookup(TRowId rowId, int dir) const noexcept
{
Y_VERIFY(dir == +1, "Only forward direction supported");
auto less = [](TRowId rowId, const THole &hole) {
return rowId < hole.End;
};
auto it = std::upper_bound(Holes.begin(), Holes.end(), rowId, less);
return it == Holes.end() ? Max<size_t>() : (it - Holes.begin());
}
THole Hole(size_t on) const noexcept
{
return on < Holes.size() ? Holes[on] : THole(false);
}
THole Bounds() const noexcept
{
return
THole(
Holes ? Holes[0].Begin : Max<TRowId>(),
Holes ? Holes.back().End : Max<TRowId>() );
}
void Validate() const noexcept
{
TRowId last = 0;
for (const auto &hole : Holes) {
Y_VERIFY(std::exchange(last, hole.End) <= hole.Begin,
"Screen not sorted or has intersections");
}
}
static TIntrusiveConstPtr<TScreen> Cut(TIntrusiveConstPtr<TScreen> scr, THole hole) noexcept
{
if (hole == THole(true)) {
return scr;
} else if (scr == nullptr || !hole) {
return hole ? new TScreen({ hole }) : new TScreen({});
}
auto first = scr->Lookup(hole.Begin, +1);
if (hole.Cut(scr->Hole(first))) {
auto last = scr->Lookup(hole.End, +1);
last = Min(last, scr->Size() - 1);
if (hole.End <= scr->Hole(last).Begin) {
last = Max(first, last - 1);
}
TVec sub(last - first + 1, THole(false));
std::copy(
scr->begin() + first, scr->begin() + last + 1, sub.begin());
sub.front() = hole.Cut(sub.front());
sub.back() = hole.Cut(sub.back());
if (!sub.front() || !sub.back()) {
Y_FAIL("Produced trival edges on screen cutting");
}
return new TScreen(std::move(sub));
} else {
return new TScreen({ /* opaque screen */});
}
}
static TIntrusiveConstPtr<TScreen> Join(TIntrusiveConstPtr<TScreen> one, TIntrusiveConstPtr<TScreen> two)
{
if (one == nullptr || one->Size() == 0) {
return two;
} else if (two == nullptr || two->Size() == 0) {
return one;
} else if (one->Bounds().Cut(two->Bounds())) {
Y_FAIL("Cannot join two intersecting screens");
} else if (one->Bounds().End > two->Bounds().Begin) {
std::swap(one, two);
}
size_t glide = (one->Bounds().End == two->Bounds().Begin ? 1 : 0);
TVec sub(one->Size() + two->Size() - glide, THole(false));
std::copy(one->begin(), one->end(), sub.begin());
if (glide) {
sub[one->Size() - 1].End = two->begin()->End;
}
std::copy(
two->begin() + glide, two->end(), sub.begin() + one->Size());
if (sub.size() != 1 || !(sub[0] == THole(true))) {
return new TScreen(std::move(sub));
} else {
return nullptr; /* transparent screen */
}
}
private:
const TVector<THole> Holes;
};
}
}
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