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#pragma once
#include "coding/reader.hpp"
/// Reader wrapper to avoid penalty on copy and polymorphic SubReader creation.
template <class ReaderT> class SubReaderWrapper
{
ReaderT * m_p;
uint64_t m_pos;
uint64_t m_size;
protected:
SubReaderWrapper(ReaderT * p, uint64_t pos, uint64_t size)
: m_p(p), m_pos(pos), m_size(size)
{
ASSERT_LESS_OR_EQUAL ( pos + size, m_p->Size(), (pos, size) );
}
public:
explicit SubReaderWrapper(ReaderT * p) : m_p(p), m_pos(0), m_size(p->Size()) {}
uint64_t Size() const { return m_size; }
void Read(uint64_t pos, void * p, size_t size) const
{
ASSERT_LESS_OR_EQUAL ( pos + size, m_size, (pos, size) );
m_p->Read(pos + m_pos, p, size);
}
SubReaderWrapper SubReader(uint64_t pos, uint64_t size) const
{
return SubReaderWrapper(m_p, pos + m_pos, size);
}
};
/// Non template reader source for regular functions with incapsulated implementation.
class ReaderSrc : public ReaderSource<SubReaderWrapper<Reader>>
{
typedef SubReaderWrapper<Reader> ReaderT;
typedef ReaderSource<ReaderT> BaseT;
public:
explicit ReaderSrc(Reader & reader) : BaseT(ReaderT(&reader)) {}
explicit ReaderSrc(Reader * reader) : BaseT(ReaderT(reader)) {}
};
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