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#ifndef UTIL_KEY_VALUE_PACKING__
#define UTIL_KEY_VALUE_PACKING__
/* Why such a general interface? I'm planning on doing bit-level packing. */
#include <algorithm>
#include <cstddef>
#include <cstring>
#include <inttypes.h>
namespace util {
template <class Key, class Value> struct Entry {
Key key;
Value value;
const Key &GetKey() const { return key; }
const Value &GetValue() const { return value; }
void Set(const Key &key_in, const Value &value_in) {
SetKey(key_in);
SetValue(value_in);
}
void SetKey(const Key &key_in) { key = key_in; }
void SetValue(const Value &value_in) { value = value_in; }
bool operator<(const Entry<Key, Value> &other) const { return GetKey() < other.GetKey(); }
};
// And now for a brief interlude to specialize std::swap.
} // namespace util
namespace std {
template <class Key, class Value> void swap(util::Entry<Key, Value> &first, util::Entry<Key, Value> &second) {
swap(first.key, second.key);
swap(first.value, second.value);
}
}// namespace std
namespace util {
template <class KeyT, class ValueT> class AlignedPacking {
public:
typedef KeyT Key;
typedef ValueT Value;
public:
static const std::size_t kBytes = sizeof(Entry<Key, Value>);
static const std::size_t kBits = kBytes * 8;
typedef Entry<Key, Value> * MutableIterator;
typedef const Entry<Key, Value> * ConstIterator;
typedef const Entry<Key, Value> & ConstReference;
static MutableIterator FromVoid(void *start) {
return reinterpret_cast<MutableIterator>(start);
}
static Entry<Key, Value> Make(const Key &key, const Value &value) {
Entry<Key, Value> ret;
ret.Set(key, value);
return ret;
}
};
template <class KeyT, class ValueT> class ByteAlignedPacking {
public:
typedef KeyT Key;
typedef ValueT Value;
private:
#pragma pack(push)
#pragma pack(1)
struct RawEntry {
Key key;
Value value;
const Key &GetKey() const { return key; }
const Value &GetValue() const { return value; }
void Set(const Key &key_in, const Value &value_in) {
SetKey(key_in);
SetValue(value_in);
}
void SetKey(const Key &key_in) { key = key_in; }
void SetValue(const Value &value_in) { value = value_in; }
bool operator<(const RawEntry &other) const { return GetKey() < other.GetKey(); }
};
#pragma pack(pop)
friend void std::swap<>(RawEntry&, RawEntry&);
public:
typedef RawEntry *MutableIterator;
typedef const RawEntry *ConstIterator;
typedef RawEntry &ConstReference;
static const std::size_t kBytes = sizeof(RawEntry);
static const std::size_t kBits = kBytes * 8;
static MutableIterator FromVoid(void *start) {
return MutableIterator(reinterpret_cast<RawEntry*>(start));
}
static RawEntry Make(const Key &key, const Value &value) {
RawEntry ret;
ret.Set(key, value);
return ret;
}
};
} // namespace util
namespace std {
template <class Key, class Value> void swap(
typename util::ByteAlignedPacking<Key, Value>::RawEntry &first,
typename util::ByteAlignedPacking<Key, Value>::RawEntry &second) {
swap(first.key, second.key);
swap(first.value, second.value);
}
}// namespace std
#endif // UTIL_KEY_VALUE_PACKING__
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