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#pragma once
#include "coding/reader.hpp"
#include "base/assert.hpp"
#include "base/exception.hpp"
#include "std/iterator_facade.hpp"
#include <type_traits>
// Disk-driven vector.
template <typename T, class TReader, typename TSize = uint32_t>
class DDVector
{
public:
typedef T value_type;
typedef TSize size_type;
typedef std::make_signed_t<size_type> difference_type;
typedef TReader ReaderType;
DECLARE_EXCEPTION(OpenException, RootException);
DDVector() : m_Size(0) {}
explicit DDVector(TReader const & reader) : m_reader(reader)
{
InitSize();
}
void Init(TReader const & reader)
{
m_reader = reader;
InitSize();
}
size_type size() const
{
return m_Size;
}
T const operator [] (size_type i) const
{
return ReadPrimitiveFromPos<T>(m_reader, static_cast<uint64_t>(i) * sizeof(T));
}
class const_iterator : public iterator_facade<
const_iterator,
value_type const,
random_access_traversal_tag>
{
public:
const_iterator() : m_pReader(NULL), m_I(0), m_bValueRead(false)
{
}
#ifdef DEBUG
const_iterator(ReaderType const * pReader, size_type i, size_type size)
: m_pReader(pReader), m_I(i), m_bValueRead(false), m_Size(size)
{
ASSERT(static_cast<difference_type>(m_Size) >= 0, ());
}
#else
const_iterator(ReaderType const * pReader, size_type i)
: m_pReader(pReader), m_I(i), m_bValueRead(false)
{
}
#endif
T const & dereference() const
{
ASSERT_LESS(m_I, m_Size, (m_bValueRead));
if (!m_bValueRead)
{
m_Value = ReadPrimitiveFromPos<T>(*m_pReader, static_cast<uint64_t>(m_I) * sizeof(T));
m_bValueRead = true;
}
return m_Value;
}
void advance(difference_type n)
{
ASSERT_LESS_OR_EQUAL(m_I, m_Size, (m_bValueRead));
m_I += n;
ASSERT_LESS_OR_EQUAL(m_I, m_Size, (m_bValueRead));
m_bValueRead = false;
}
difference_type distance_to(const_iterator const & it) const
{
ASSERT_LESS_OR_EQUAL(m_I, m_Size, (m_bValueRead));
ASSERT_LESS_OR_EQUAL(it.m_I, it.m_Size, (it.m_bValueRead));
ASSERT_EQUAL(m_Size, it.m_Size, (m_I, it.m_I, m_bValueRead, it.m_bValueRead));
ASSERT(m_pReader == it.m_pReader, (m_I, m_Size, it.m_I, it.m_Size));
return (static_cast<difference_type>(it.m_I) -
static_cast<difference_type>(m_I));
}
void increment()
{
++m_I;
m_bValueRead = false;
ASSERT_LESS_OR_EQUAL(m_I, m_Size, (m_bValueRead));
}
void decrement()
{
--m_I;
m_bValueRead = false;
ASSERT_LESS_OR_EQUAL(m_I, m_Size, (m_bValueRead));
}
bool equal(const_iterator const & it) const
{
ASSERT_LESS_OR_EQUAL(m_I, m_Size, (m_bValueRead));
ASSERT_LESS_OR_EQUAL(it.m_I, it.m_Size, (it.m_bValueRead));
ASSERT_EQUAL(m_Size, it.m_Size, (m_I, it.m_I, m_bValueRead, it.m_bValueRead));
ASSERT(m_pReader == it.m_pReader, (m_I, m_Size, it.m_I, it.m_Size));
return m_I == it.m_I;
}
private:
ReaderType const * m_pReader;
size_type m_I;
mutable T m_Value;
mutable bool m_bValueRead;
#ifdef DEBUG
size_type m_Size;
#endif
};
const_iterator begin() const
{
#ifdef DEBUG
return const_iterator(&m_reader, 0, m_Size);
#else
return const_iterator(&m_reader, 0);
#endif
}
const_iterator end() const
{
#ifdef DEBUG
return const_iterator(&m_reader, m_Size, m_Size);
#else
return const_iterator(&m_reader, m_Size);
#endif
}
void Read(size_type i, T & result) const
{
ASSERT_LESS(i, m_Size, ());
ReadFromPos(m_reader, i * sizeof(T), &result, sizeof(T));
}
void Read(size_type i, T * result, size_t count)
{
ASSERT_LESS(i + count, m_Size, (i, count));
ReadFromPos(m_reader, i * sizeof(T), result, count * sizeof(T));
}
private:
void InitSize()
{
uint64_t const sz = m_reader.Size();
if ((sz % sizeof(T)) != 0)
MYTHROW(OpenException, ("Element size", sizeof(T), "does not divide total size", sz));
m_Size = static_cast<size_type>(sz / sizeof(T));
}
// TODO: Refactor me to use Reader by pointer.
ReaderType m_reader;
size_type m_Size;
};
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