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#ifndef UTIL_SORTED_UNIFORM__
#define UTIL_SORTED_UNIFORM__
#include <algorithm>
#include <cstddef>
#include <assert.h>
#include <inttypes.h>
namespace util {
inline std::size_t Pivot(uint64_t off, uint64_t range, std::size_t width) {
std::size_t ret = static_cast<std::size_t>(static_cast<float>(off) / static_cast<float>(range) * static_cast<float>(width));
// Cap for floating point rounding
return (ret < width) ? ret : width - 1;
}
/*inline std::size_t Pivot(uint32_t off, uint32_t range, std::size_t width) {
return static_cast<std::size_t>(static_cast<uint64_t>(off) * static_cast<uint64_t>(width) / static_cast<uint64_t>(range));
}
inline std::size_t Pivot(uint16_t off, uint16_t range, std::size_t width) {
return static_cast<std::size_t>(static_cast<std::size_t>(off) * width / static_cast<std::size_t>(range));
}
inline std::size_t Pivot(unsigned char off, unsigned char range, std::size_t width) {
return static_cast<std::size_t>(static_cast<std::size_t>(off) * width / static_cast<std::size_t>(range));
}*/
template <class Iterator, class Key> bool SortedUniformFind(Iterator begin, Iterator end, const Key key, Iterator &out) {
if (begin == end) return false;
Key below(begin->GetKey());
if (key <= below) {
if (key == below) { out = begin; return true; }
return false;
}
// Make the range [begin, end].
--end;
Key above(end->GetKey());
if (key >= above) {
if (key == above) { out = end; return true; }
return false;
}
// Search the range [begin + 1, end - 1] knowing that *begin == below, *end == above.
while (end - begin > 1) {
Iterator pivot(begin + (1 + Pivot(key - below, above - below, static_cast<std::size_t>(end - begin - 1))));
Key mid(pivot->GetKey());
if (mid < key) {
begin = pivot;
below = mid;
} else if (mid > key) {
end = pivot;
above = mid;
} else {
out = pivot;
return true;
}
}
return false;
}
// To use this template, you need to define a Pivot function to match Key.
template <class PackingT> class SortedUniformMap {
public:
typedef PackingT Packing;
typedef typename Packing::ConstIterator ConstIterator;
typedef typename Packing::MutableIterator MutableIterator;
public:
// Offer consistent API with probing hash.
static std::size_t Size(std::size_t entries, float /*ignore*/ = 0.0) {
return sizeof(uint64_t) + entries * Packing::kBytes;
}
SortedUniformMap()
#ifdef DEBUG
: initialized_(false), loaded_(false)
#endif
{}
SortedUniformMap(void *start, std::size_t /*allocated*/) :
begin_(Packing::FromVoid(reinterpret_cast<uint64_t*>(start) + 1)),
end_(begin_), size_ptr_(reinterpret_cast<uint64_t*>(start))
#ifdef DEBUG
, initialized_(true), loaded_(false)
#endif
{}
void LoadedBinary() {
#ifdef DEBUG
assert(initialized_);
assert(!loaded_);
loaded_ = true;
#endif
// Restore the size.
end_ = begin_ + *size_ptr_;
}
// Caller responsible for not exceeding specified size. Do not call after FinishedInserting.
template <class T> void Insert(const T &t) {
#ifdef DEBUG
assert(initialized_);
assert(!loaded_);
#endif
*end_ = t;
++end_;
}
void FinishedInserting() {
#ifdef DEBUG
assert(initialized_);
assert(!loaded_);
loaded_ = true;
#endif
std::sort(begin_, end_);
*size_ptr_ = (end_ - begin_);
}
// Don't use this to change the key.
template <class Key> bool UnsafeMutableFind(const Key key, MutableIterator &out) {
#ifdef DEBUG
assert(initialized_);
assert(loaded_);
#endif
return SortedUniformFind<MutableIterator, Key>(begin_, end_, key, out);
}
// Do not call before FinishedInserting.
template <class Key> bool Find(const Key key, ConstIterator &out) const {
#ifdef DEBUG
assert(initialized_);
assert(loaded_);
#endif
return SortedUniformFind<ConstIterator, Key>(ConstIterator(begin_), ConstIterator(end_), key, out);
}
ConstIterator begin() const { return begin_; }
ConstIterator end() const { return end_; }
private:
typename Packing::MutableIterator begin_, end_;
uint64_t *size_ptr_;
#ifdef DEBUG
bool initialized_;
bool loaded_;
#endif
};
} // namespace util
#endif // UTIL_SORTED_UNIFORM__
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