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80 lines
2.7 KiB
C++
80 lines
2.7 KiB
C++
#pragma once
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#include <DB/Columns/IColumn.h>
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namespace DB
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{
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/** Базовый класс для столбцов-констант, содержащих значение, не входящее в Field.
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* Не является полноценым столбцом и используется особым образом.
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*/
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class IColumnDummy : public IColumn
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{
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public:
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IColumnDummy(size_t s_) : s(s_) {}
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virtual ColumnPtr cloneDummy(size_t s_) const = 0;
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ColumnPtr cloneResized(size_t s_) const override { return cloneDummy(s_); }
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bool isConst() const override { return true; }
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size_t size() const override { return s; }
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void insertDefault() override { ++s; }
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size_t byteSize() const override { return 0; }
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int compareAt(size_t n, size_t m, const IColumn & rhs_, int nan_direction_hint) const override { return 0; }
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Field operator[](size_t n) const override { throw Exception("Cannot get value from " + getName(), ErrorCodes::NOT_IMPLEMENTED); }
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void get(size_t n, Field & res) const override { throw Exception("Cannot get value from " + getName(), ErrorCodes::NOT_IMPLEMENTED); };
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void insert(const Field & x) override { throw Exception("Cannot insert element into " + getName(), ErrorCodes::NOT_IMPLEMENTED); }
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StringRef getDataAt(size_t n) const override { throw Exception("Method getDataAt is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED); }
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void insertData(const char * pos, size_t length) override { throw Exception("Method insertData is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED); }
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void getExtremes(Field & min, Field & max) const override
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{
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throw Exception("Method getExtremes is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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ColumnPtr cut(size_t start, size_t length) const override
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{
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return cloneDummy(length);
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}
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ColumnPtr filter(const Filter & filt) const override
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{
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size_t new_size = 0;
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for (Filter::const_iterator it = filt.begin(); it != filt.end(); ++it)
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if (*it)
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++new_size;
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return cloneDummy(new_size);
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}
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ColumnPtr permute(const Permutation & perm, size_t limit) const override
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{
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if (s != perm.size())
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throw Exception("Size of permutation doesn't match size of column.", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);
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return cloneDummy(limit ? std::min(s, limit) : s);
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}
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void getPermutation(bool reverse, size_t limit, Permutation & res) const override
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{
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res.resize(s);
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for (size_t i = 0; i < s; ++i)
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res[i] = i;
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}
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ColumnPtr replicate(const Offsets_t & offsets) const override
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{
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if (s != offsets.size())
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throw Exception("Size of offsets doesn't match size of column.", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);
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return cloneDummy(s == 0 ? 0 : offsets.back());
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}
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private:
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size_t s;
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};
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}
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