2021-05-17 07:30:42 +00:00
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#include <Functions/IFunction.h>
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2020-04-12 01:24:00 +00:00
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#include <Functions/FunctionFactory.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <Columns/ColumnsNumber.h>
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namespace DB
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{
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2020-09-07 18:00:37 +00:00
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namespace
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{
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2020-04-12 01:24:00 +00:00
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/// Returns 1 if and only if the argument is constant expression.
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2020-04-12 01:26:11 +00:00
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/// This function exists for development, debugging and demonstration purposes.
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2020-04-12 01:24:00 +00:00
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class FunctionIsConstant : public IFunction
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{
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public:
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static constexpr auto name = "isConstant";
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2021-06-01 12:20:52 +00:00
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static FunctionPtr create(ContextPtr)
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2020-04-12 01:24:00 +00:00
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{
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return std::make_shared<FunctionIsConstant>();
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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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2022-05-12 15:15:31 +00:00
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bool useDefaultImplementationForNothing() const override { return false; }
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2022-07-13 17:56:34 +00:00
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bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }
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2021-06-22 16:21:23 +00:00
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bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
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2021-04-29 14:48:26 +00:00
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2020-04-12 01:24:00 +00:00
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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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return std::make_shared<DataTypeUInt8>();
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}
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2020-11-17 13:24:45 +00:00
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ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
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2020-04-12 01:24:00 +00:00
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{
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2020-10-19 13:42:14 +00:00
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const auto & elem = arguments[0];
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return ColumnUInt8::create(input_rows_count, isColumnConst(*elem.column));
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2020-04-12 01:24:00 +00:00
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}
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};
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2020-09-07 18:00:37 +00:00
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}
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2020-04-12 01:24:00 +00:00
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2022-07-04 07:01:39 +00:00
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REGISTER_FUNCTION(IsConstant)
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2020-04-12 01:24:00 +00:00
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{
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factory.registerFunction<FunctionIsConstant>();
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}
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}
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