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

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#pragma once
#include <string>
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#include <DB/IO/WriteBuffer.h>
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#define WRITE_BUFFER_FROM_STRING_INITIAL_SIZE_IF_EMPTY 32
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namespace DB
{
/** Пишет данные в строку.
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* Замечение: перед использованием полученной строки, уничтожте этот объект.
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*/
class WriteBufferFromString : public WriteBuffer
{
private:
std::string & s;
void nextImpl() override
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{
size_t old_size = s.size();
s.resize(old_size * 2);
internal_buffer = Buffer(reinterpret_cast<Position>(&s[old_size]), reinterpret_cast<Position>(&*s.end()));
working_buffer = internal_buffer;
}
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void finish()
{
s.resize(count());
}
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public:
WriteBufferFromString(std::string & s_)
: WriteBuffer(reinterpret_cast<Position>(&s_[0]), s_.size()), s(s_)
{
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if (s.empty())
{
s.resize(WRITE_BUFFER_FROM_STRING_INITIAL_SIZE_IF_EMPTY);
set(reinterpret_cast<Position>(&s[0]), s.size());
}
}
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~WriteBufferFromString() override
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{
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finish();
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}
};
}