ClickHouse/dbms/include/DB/IO/WriteBufferFromVector.h

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2011-10-16 01:57:10 +00:00
#pragma once
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#include <vector>
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#include <DB/IO/WriteBuffer.h>
#define WRITE_BUFFER_FROM_VECTOR_INITIAL_SIZE_IF_EMPTY 32
namespace DB
{
/** Инициализируется вектором. Пишет данные в него. Когда вектор закончится - увеличивает его размер в два раза.
* CharType - char или unsigned char.
*/
template <typename CharType>
class WriteBufferFromVector : public WriteBuffer
{
private:
typedef std::vector<CharType> VectorType;
VectorType & vector;
void nextImpl()
{
size_t old_size = vector.size();
vector.resize(old_size * 2);
internal_buffer = Buffer(reinterpret_cast<Position>(&vector[old_size]), reinterpret_cast<Position>(&*vector.end()));
working_buffer = internal_buffer;
}
public:
WriteBufferFromVector(VectorType & vector_)
: WriteBuffer(reinterpret_cast<Position>(&vector_[0]), vector_.size()), vector(vector_)
{
if (vector.empty())
{
vector.resize(WRITE_BUFFER_FROM_VECTOR_INITIAL_SIZE_IF_EMPTY);
set(reinterpret_cast<Position>(&vector[0]), vector.size());
}
}
};
}