ClickHouse/dbms/src/IO/WriteBufferFromVector.h

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#pragma once
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#include <vector>
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#include <IO/WriteBuffer.h>
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#define WRITE_BUFFER_FROM_VECTOR_INITIAL_SIZE_IF_EMPTY 32
namespace DB
{
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/** Initialized by vector. Writes data to it. When the vector is finished, it doubles its size.
* CharType - char or unsigned char.
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*/
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template <typename VectorType = std::vector<char>>
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class WriteBufferFromVector : public WriteBuffer
{
private:
VectorType & vector;
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void nextImpl() override
{
size_t old_size = vector.size();
vector.resize(old_size * 2);
internal_buffer = Buffer(reinterpret_cast<Position>(&vector[old_size]), reinterpret_cast<Position>(vector.data() + vector.size()));
working_buffer = internal_buffer;
}
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public:
WriteBufferFromVector(VectorType & vector_)
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: WriteBuffer(reinterpret_cast<Position>(vector_.data()), 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());
}
}
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};
}