ClickHouse/dbms/src/Columns/ColumnFunction.h

#pragma once

#include <Core/NamesAndTypes.h>
#include <Core/ColumnsWithTypeAndName.h>
#include <Columns/IColumn.h>

class IFunctionBase;
using FunctionBasePtr = std::shared_ptr<IFunctionBase>;


namespace DB
{


/** A column containing a lambda expression.
  * Behaves like a constant-column. Contains an expression, but not input or output data.
  */
class ColumnFunction final : public COWPtrHelper<IColumn, ColumnFunction>
{
private:
    friend class COWPtrHelper<IColumn, ColumnFunction>;

    ColumnFunction(size_t size, FunctionBasePtr function, const ColumnsWithTypeAndName & columns_to_capture);

public:
    const char * getFamilyName() const override { return "Function"; }

    MutableColumnPtr cloneResized(size_t size) const override;

    size_t size() const override { return size_; }

    ColumnPtr cut(size_t start, size_t length) const override;
    ColumnPtr replicate(const Offsets & offsets) const override;
    ColumnPtr filter(const Filter & filt, ssize_t result_size_hint) const override;
    ColumnPtr permute(const Permutation & perm, UInt64 limit) const override;
    ColumnPtr index(const IColumn & indexes, size_t limit) const override;
    void insertDefault() override;
    void popBack(size_t n) override;
    std::vector<MutableColumnPtr> scatter(IColumn::ColumnIndex num_columns,
                                          const IColumn::Selector & selector) const override;

    void getExtremes(Field &, Field &) const override {}

    size_t byteSize() const override;
    size_t allocatedBytes() const override;

    void appendArguments(const ColumnsWithTypeAndName & columns);
    ColumnWithTypeAndName reduce() const;

    Field operator[](size_t) const override
    {
        throw Exception("Cannot get value from " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    void get(size_t, Field &) const override
    {
        throw Exception("Cannot get value from " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    StringRef getDataAt(size_t) const override
    {
        throw Exception("Cannot get value from " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    void insert(const Field &) override
    {
        throw Exception("Cannot get insert into " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    void insertRangeFrom(const IColumn &, size_t, size_t) override
    {
        throw Exception("Cannot insert into " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    void insertData(const char *, size_t) override
    {
        throw Exception("Cannot insert into " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    StringRef serializeValueIntoArena(size_t, Arena &, char const *&) const override
    {
        throw Exception("Cannot serialize from " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    const char * deserializeAndInsertFromArena(const char *) override
    {
        throw Exception("Cannot deserialize to " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    void updateHashWithValue(size_t, SipHash &) const override
    {
        throw Exception("updateHashWithValue is not implemented for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    int compareAt(size_t, size_t, const IColumn &, int) const override
    {
        throw Exception("compareAt is not implemented for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    void getPermutation(bool, size_t, int, Permutation &) const override
    {
        throw Exception("getPermutation is not implemented for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

    void gather(ColumnGathererStream &) override
    {
        throw Exception("Method gather is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
    }

private:
    size_t size_;
    FunctionBasePtr function;
    ColumnsWithTypeAndName captured_columns;

    void appendArgument(const ColumnWithTypeAndName & column);
};

}