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#pragma once
#include <Processors/ISource.h>
namespace DB
{
/** A stream of blocks from which you can read the next block from an explicitly provided list.
* Also see SourceFromSingleChunk.
*/
class BlocksListSource : public ISource
{
public:
/// Acquires the ownership of the block list.
explicit BlocksListSource(BlocksList && list_)
: ISource(list_.empty() ? Block() : list_.front().cloneEmpty())
, list(std::move(list_)), it(list.begin()), end(list.end()) {}
/// Uses a list of blocks lying somewhere else.
BlocksListSource(BlocksList::iterator & begin_, BlocksList::iterator & end_)
: ISource(begin_ == end_ ? Block() : begin_->cloneEmpty())
, it(begin_), end(end_) {}
String getName() const override { return "BlocksListSource"; }
protected:
Chunk generate() override
{
if (it == end)
return {};
Block res = *it;
++it;
size_t num_rows = res.rows();
return Chunk(res.getColumns(), num_rows);
}
private:
BlocksList list;
BlocksList::iterator it;
const BlocksList::iterator end;
};
}
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