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153 lines
5.0 KiB
C++
153 lines
5.0 KiB
C++
#include <Functions/IFunction.h>
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#include <Functions/FunctionFactory.h>
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#include <Functions/FunctionHelpers.h>
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#include <DataTypes/IDataType.h>
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#include <DataTypes/DataTypeTuple.h>
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#include <DataTypes/DataTypeArray.h>
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#include <Columns/ColumnTuple.h>
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#include <Columns/ColumnArray.h>
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#include <Columns/ColumnString.h>
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#include <Columns/ColumnsNumber.h>
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#include <Common/assert_cast.h>
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#include <memory>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int ILLEGAL_TYPE_OF_ARGUMENT;
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extern const int ILLEGAL_INDEX;
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}
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namespace
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{
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/** Extract element of tuple by constant index or name. The operation is essentially free.
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* Also the function looks through Arrays: you can get Array of tuple elements from Array of Tuples.
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*/
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class FunctionTupleElement : public IFunction
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{
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public:
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static constexpr auto name = "tupleElement";
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static FunctionPtr create(ContextPtr)
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{
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return std::make_shared<FunctionTupleElement>();
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}
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String getName() const override
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{
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return name;
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}
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size_t getNumberOfArguments() const override
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{
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return 2;
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}
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bool useDefaultImplementationForConstants() const override
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{
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return true;
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}
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ColumnNumbers getArgumentsThatAreAlwaysConstant() const override
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{
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return {1};
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}
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bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
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DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
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{
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size_t count_arrays = 0;
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const IDataType * tuple_col = arguments[0].type.get();
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while (const DataTypeArray * array = checkAndGetDataType<DataTypeArray>(tuple_col))
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{
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tuple_col = array->getNestedType().get();
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++count_arrays;
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}
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const DataTypeTuple * tuple = checkAndGetDataType<DataTypeTuple>(tuple_col);
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if (!tuple)
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throw Exception("First argument for function " + getName() + " must be tuple or array of tuple.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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size_t index = getElementNum(arguments[1].column, *tuple);
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DataTypePtr out_return_type = tuple->getElements()[index];
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for (; count_arrays; --count_arrays)
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out_return_type = std::make_shared<DataTypeArray>(out_return_type);
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return out_return_type;
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}
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ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t /*input_rows_count*/) const override
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{
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Columns array_offsets;
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const auto & first_arg = arguments[0];
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const IDataType * tuple_type = first_arg.type.get();
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const IColumn * tuple_col = first_arg.column.get();
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while (const DataTypeArray * array_type = checkAndGetDataType<DataTypeArray>(tuple_type))
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{
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const ColumnArray * array_col = assert_cast<const ColumnArray *>(tuple_col);
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tuple_type = array_type->getNestedType().get();
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tuple_col = &array_col->getData();
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array_offsets.push_back(array_col->getOffsetsPtr());
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}
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const DataTypeTuple * tuple_type_concrete = checkAndGetDataType<DataTypeTuple>(tuple_type);
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const ColumnTuple * tuple_col_concrete = checkAndGetColumn<ColumnTuple>(tuple_col);
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if (!tuple_type_concrete || !tuple_col_concrete)
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throw Exception("First argument for function " + getName() + " must be tuple or array of tuple.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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size_t index = getElementNum(arguments[1].column, *tuple_type_concrete);
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ColumnPtr res = tuple_col_concrete->getColumns()[index];
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/// Wrap into Arrays
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for (auto it = array_offsets.rbegin(); it != array_offsets.rend(); ++it)
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res = ColumnArray::create(res, *it);
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return res;
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}
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private:
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size_t getElementNum(const ColumnPtr & index_column, const DataTypeTuple & tuple) const
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{
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if (
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checkAndGetColumnConst<ColumnUInt8>(index_column.get())
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|| checkAndGetColumnConst<ColumnUInt16>(index_column.get())
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|| checkAndGetColumnConst<ColumnUInt32>(index_column.get())
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|| checkAndGetColumnConst<ColumnUInt64>(index_column.get())
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)
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{
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size_t index = index_column->getUInt(0);
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if (index == 0)
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throw Exception("Indices in tuples are 1-based.", ErrorCodes::ILLEGAL_INDEX);
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if (index > tuple.getElements().size())
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throw Exception("Index for tuple element is out of range.", ErrorCodes::ILLEGAL_INDEX);
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return index - 1;
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}
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else if (const auto * name_col = checkAndGetColumnConst<ColumnString>(index_column.get()))
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{
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return tuple.getPositionByName(name_col->getValue<String>());
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}
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else
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throw Exception("Second argument to " + getName() + " must be a constant UInt or String", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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}
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};
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}
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void registerFunctionTupleElement(FunctionFactory & factory)
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{
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factory.registerFunction<FunctionTupleElement>();
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}
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}
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