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74 lines
2.3 KiB
C++
74 lines
2.3 KiB
C++
#include <Functions/IFunctionImpl.h>
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#include <Functions/FunctionFactory.h>
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#include <Functions/FunctionHelpers.h>
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#include <DataTypes/DataTypeEnum.h>
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#include <DataTypes/DataTypesNumber.h>
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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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}
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/// Returns number of fields in Enum data type of passed value.
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class FunctionGetSizeOfEnumType : public IFunction
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{
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public:
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static constexpr auto name = "getSizeOfEnumType";
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static FunctionPtr create(const Context &)
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{
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return std::make_shared<FunctionGetSizeOfEnumType>();
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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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bool useDefaultImplementationForNulls() const override { return false; }
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size_t getNumberOfArguments() const override
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{
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return 1;
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}
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DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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{
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WhichDataType which(arguments[0]);
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if (which.isEnum8())
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return std::make_shared<DataTypeUInt8>();
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else if (which.isEnum16())
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return std::make_shared<DataTypeUInt16>();
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throw Exception("The argument for function " + getName() + " must be Enum", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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}
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void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) override
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{
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block.getByPosition(result).column = getResultIfAlwaysReturnsConstantAndHasArguments(block, arguments)->cloneResized(input_rows_count);
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}
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ColumnPtr getResultIfAlwaysReturnsConstantAndHasArguments(const Block & block, const ColumnNumbers & arguments) const override
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{
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if (auto type8 = checkAndGetDataType<DataTypeEnum8>(block.getByPosition(arguments[0]).type.get()))
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return DataTypeUInt8().createColumnConst(1, type8->getValues().size());
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else if (auto type16 = checkAndGetDataType<DataTypeEnum16>(block.getByPosition(arguments[0]).type.get()))
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return DataTypeUInt16().createColumnConst(1, type16->getValues().size());
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else
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throw Exception("The argument for function " + getName() + " must be Enum", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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}
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};
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void registerFunctionGetSizeOfEnumType(FunctionFactory & factory)
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{
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factory.registerFunction<FunctionGetSizeOfEnumType>();
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}
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}
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