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329 lines
15 KiB
C++
329 lines
15 KiB
C++
#pragma once
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#include <Functions/IFunction.h>
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/// This file contains developer interface for functions.
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/// In order to implement a new function you can choose one of two options:
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/// * Implement interface for IFunction (old function interface, which is planned to be removed sometimes)
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/// * Implement three interfaces for IExecutableFunctionImpl, IFunctionBaseImpl and IFunctionOverloadResolverImpl
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/// Generally saying, IFunction represents a union of tree new interfaces. However, it can't be used for all cases.
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/// Examples:
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/// * Function properties may depend on arguments type (e.g. toUInt32(UInt8) is globally monotonic, toUInt32(UInt64) - only on intervals)
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/// * In implementation of lambda functions DataTypeFunction needs an functional object with known arguments and return type
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/// * Function CAST prepares specific implementation based on argument types
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///
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/// Interfaces for IFunction, IExecutableFunctionImpl, IFunctionBaseImpl and IFunctionOverloadResolverImpl are pure.
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/// Default implementations are in adaptors classes (IFunctionAdaptors.h), which are implement user interfaces via developer ones.
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/// Interfaces IExecutableFunctionImpl, IFunctionBaseImpl and IFunctionOverloadResolverImpl are implemented via IFunction
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/// in DefaultExecutable, DefaultFunction and DefaultOverloadResolver classes (IFunctionAdaptors.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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extern const int NOT_IMPLEMENTED;
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}
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/// Cache for functions result if it was executed on low cardinality column.
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class ExecutableFunctionLowCardinalityResultCache;
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using ExecutableFunctionLowCardinalityResultCachePtr = std::shared_ptr<ExecutableFunctionLowCardinalityResultCache>;
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class IExecutableFunctionImpl
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{
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public:
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virtual ~IExecutableFunctionImpl() = default;
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virtual String getName() const = 0;
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virtual void execute(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) = 0;
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virtual void executeDryRun(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count)
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{
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execute(block, arguments, result, input_rows_count);
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}
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/** Default implementation in presence of Nullable arguments or NULL constants as arguments is the following:
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* if some of arguments are NULL constants then return NULL constant,
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* if some of arguments are Nullable, then execute function as usual for block,
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* where Nullable columns are substituted with nested columns (they have arbitrary values in rows corresponding to NULL value)
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* and wrap result in Nullable column where NULLs are in all rows where any of arguments are NULL.
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*/
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virtual bool useDefaultImplementationForNulls() const { return true; }
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/** If the function have non-zero number of arguments,
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* and if all arguments are constant, that we could automatically provide default implementation:
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* arguments are converted to ordinary columns with single value, then function is executed as usual,
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* and then the result is converted to constant column.
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*/
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virtual bool useDefaultImplementationForConstants() const { return false; }
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/** If function arguments has single low cardinality column and all other arguments are constants, call function on nested column.
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* Otherwise, convert all low cardinality columns to ordinary columns.
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* Returns ColumnLowCardinality if at least one argument is ColumnLowCardinality.
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*/
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virtual bool useDefaultImplementationForLowCardinalityColumns() const { return true; }
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/** Some arguments could remain constant during this implementation.
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*/
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virtual ColumnNumbers getArgumentsThatAreAlwaysConstant() const { return {}; }
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/** True if function can be called on default arguments (include Nullable's) and won't throw.
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* Counterexample: modulo(0, 0)
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*/
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virtual bool canBeExecutedOnDefaultArguments() const { return true; }
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};
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using ExecutableFunctionImplPtr = std::unique_ptr<IExecutableFunctionImpl>;
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/// This class generally has the same methods as in IFunctionBase.
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/// See comments for IFunctionBase in IFunction.h
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/// The main purpose is to implement `prepare` which returns IExecutableFunctionImpl, not IExecutableFunction
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/// Inheritance is not used for better readability.
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class IFunctionBaseImpl
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{
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public:
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virtual ~IFunctionBaseImpl() = default;
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virtual String getName() const = 0;
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virtual const DataTypes & getArgumentTypes() const = 0;
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virtual const DataTypePtr & getReturnType() const = 0;
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virtual ExecutableFunctionImplPtr prepare(const Block & sample_block, const ColumnNumbers & arguments, size_t result) const = 0;
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#if USE_EMBEDDED_COMPILER
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virtual bool isCompilable() const { return false; }
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virtual llvm::Value * compile(llvm::IRBuilderBase & /*builder*/, ValuePlaceholders /*values*/) const
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{
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throw Exception(getName() + " is not JIT-compilable", ErrorCodes::NOT_IMPLEMENTED);
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}
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#endif
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virtual bool isStateful() const { return false; }
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virtual bool isSuitableForConstantFolding() const { return true; }
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virtual ColumnPtr getResultIfAlwaysReturnsConstantAndHasArguments(const Block & /*block*/, const ColumnNumbers & /*arguments*/) const { return nullptr; }
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virtual bool isInjective(const Block & /*sample_block*/) { return false; }
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virtual bool isDeterministic() const { return true; }
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virtual bool isDeterministicInScopeOfQuery() const { return true; }
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virtual bool hasInformationAboutMonotonicity() const { return false; }
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using Monotonicity = IFunctionBase::Monotonicity;
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virtual Monotonicity getMonotonicityForRange(const IDataType & /*type*/, const Field & /*left*/, const Field & /*right*/) const
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{
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throw Exception("Function " + getName() + " has no information about its monotonicity.", ErrorCodes::NOT_IMPLEMENTED);
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}
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};
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using FunctionBaseImplPtr = std::unique_ptr<IFunctionBaseImpl>;
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class IFunctionOverloadResolverImpl
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{
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public:
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virtual ~IFunctionOverloadResolverImpl() = default;
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virtual String getName() const = 0;
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virtual FunctionBaseImplPtr build(const ColumnsWithTypeAndName & arguments, const DataTypePtr & return_type) const = 0;
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virtual DataTypePtr getReturnType(const DataTypes & /*arguments*/) const
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{
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throw Exception("getReturnType is not implemented for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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/// This function will be called in default implementation. You can overload it or the previous one.
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virtual DataTypePtr getReturnType(const ColumnsWithTypeAndName & arguments) const
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{
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DataTypes data_types(arguments.size());
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for (size_t i = 0; i < arguments.size(); ++i)
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data_types[i] = arguments[i].type;
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return getReturnType(data_types);
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}
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/// For non-variadic functions, return number of arguments; otherwise return zero (that should be ignored).
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virtual size_t getNumberOfArguments() const = 0;
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/// Properties from IFunctionOverloadResolver. See comments in IFunction.h
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virtual bool isDeterministic() const { return true; }
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virtual bool isDeterministicInScopeOfQuery() const { return true; }
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virtual bool isStateful() const { return false; }
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virtual bool isVariadic() const { return false; }
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/// Will be called if isVariadic returns true. You need to check if function can have specified number of arguments.
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virtual void checkNumberOfArgumentsIfVariadic(size_t /*number_of_arguments*/) const
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{
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throw Exception("checkNumberOfArgumentsIfVariadic is not implemented for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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virtual void getLambdaArgumentTypes(DataTypes & /*arguments*/) const
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{
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throw Exception("Function " + getName() + " can't have lambda-expressions as arguments", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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}
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virtual ColumnNumbers getArgumentsThatAreAlwaysConstant() const { return {}; }
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virtual ColumnNumbers getArgumentsThatDontImplyNullableReturnType(size_t /*number_of_arguments*/) const { return {}; }
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/** If useDefaultImplementationForNulls() is true, than change arguments for getReturnType() and build():
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* if some of arguments are Nullable(Nothing) then don't call getReturnType(), call build() with return_type = Nullable(Nothing),
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* if some of arguments are Nullable, then:
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* - Nullable types are substituted with nested types for getReturnType() function
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* - wrap getReturnType() result in Nullable type and pass to build
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*
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* Otherwise build returns build(arguments, getReturnType(arguments));
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*/
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virtual bool useDefaultImplementationForNulls() const { return true; }
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/** If useDefaultImplementationForNulls() is true, than change arguments for getReturnType() and build().
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* If function arguments has low cardinality types, convert them to ordinary types.
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* getReturnType returns ColumnLowCardinality if at least one argument type is ColumnLowCardinality.
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*/
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virtual bool useDefaultImplementationForLowCardinalityColumns() const { return true; }
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/// If it isn't, will convert all ColumnLowCardinality arguments to full columns.
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virtual bool canBeExecutedOnLowCardinalityDictionary() const { return true; }
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};
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using FunctionOverloadResolverImplPtr = std::unique_ptr<IFunctionOverloadResolverImpl>;
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/// Previous function interface.
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class IFunction : public std::enable_shared_from_this<IFunction>
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{
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public:
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virtual ~IFunction() = default;
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virtual String getName() const = 0;
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virtual void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) = 0;
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virtual void executeImplDryRun(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count)
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{
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executeImpl(block, arguments, result, input_rows_count);
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}
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/** Default implementation in presence of Nullable arguments or NULL constants as arguments is the following:
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* if some of arguments are NULL constants then return NULL constant,
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* if some of arguments are Nullable, then execute function as usual for block,
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* where Nullable columns are substituted with nested columns (they have arbitrary values in rows corresponding to NULL value)
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* and wrap result in Nullable column where NULLs are in all rows where any of arguments are NULL.
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*/
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virtual bool useDefaultImplementationForNulls() const { return true; }
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/** If the function have non-zero number of arguments,
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* and if all arguments are constant, that we could automatically provide default implementation:
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* arguments are converted to ordinary columns with single value, then function is executed as usual,
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* and then the result is converted to constant column.
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*/
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virtual bool useDefaultImplementationForConstants() const { return false; }
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/** If function arguments has single low cardinality column and all other arguments are constants, call function on nested column.
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* Otherwise, convert all low cardinality columns to ordinary columns.
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* Returns ColumnLowCardinality if at least one argument is ColumnLowCardinality.
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*/
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virtual bool useDefaultImplementationForLowCardinalityColumns() const { return true; }
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/// If it isn't, will convert all ColumnLowCardinality arguments to full columns.
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virtual bool canBeExecutedOnLowCardinalityDictionary() const { return true; }
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/** Some arguments could remain constant during this implementation.
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*/
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virtual ColumnNumbers getArgumentsThatAreAlwaysConstant() const { return {}; }
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/** True if function can be called on default arguments (include Nullable's) and won't throw.
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* Counterexample: modulo(0, 0)
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*/
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virtual bool canBeExecutedOnDefaultArguments() const { return true; }
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#if USE_EMBEDDED_COMPILER
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virtual bool isCompilable() const
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{
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throw Exception("isCompilable without explicit types is not implemented for IFunction", ErrorCodes::NOT_IMPLEMENTED);
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}
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virtual llvm::Value * compile(llvm::IRBuilderBase & /*builder*/, ValuePlaceholders /*values*/) const
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{
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throw Exception("compile without explicit types is not implemented for IFunction", ErrorCodes::NOT_IMPLEMENTED);
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}
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#endif
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/// Properties from IFunctionBase (see IFunction.h)
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virtual bool isSuitableForConstantFolding() const { return true; }
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virtual ColumnPtr getResultIfAlwaysReturnsConstantAndHasArguments(const Block & /*block*/, const ColumnNumbers & /*arguments*/) const { return nullptr; }
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virtual bool isInjective(const Block & /*sample_block*/) { return false; }
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virtual bool isDeterministic() const { return true; }
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virtual bool isDeterministicInScopeOfQuery() const { return true; }
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virtual bool isStateful() const { return false; }
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virtual bool hasInformationAboutMonotonicity() const { return false; }
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using Monotonicity = IFunctionBase::Monotonicity;
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virtual Monotonicity getMonotonicityForRange(const IDataType & /*type*/, const Field & /*left*/, const Field & /*right*/) const
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{
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throw Exception("Function " + getName() + " has no information about its monotonicity.", ErrorCodes::NOT_IMPLEMENTED);
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}
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/// For non-variadic functions, return number of arguments; otherwise return zero (that should be ignored).
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virtual size_t getNumberOfArguments() const = 0;
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virtual DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const
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{
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throw Exception("getReturnType is not implemented for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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/// Get the result type by argument type. If the function does not apply to these arguments, throw an exception.
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virtual DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const
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{
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DataTypes data_types(arguments.size());
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for (size_t i = 0; i < arguments.size(); ++i)
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data_types[i] = arguments[i].type;
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return getReturnTypeImpl(data_types);
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}
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virtual bool isVariadic() const { return false; }
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virtual void checkNumberOfArgumentsIfVariadic(size_t /*number_of_arguments*/) const
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{
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throw Exception("checkNumberOfArgumentsIfVariadic is not implemented for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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virtual void getLambdaArgumentTypes(DataTypes & /*arguments*/) const
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{
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throw Exception("Function " + getName() + " can't have lambda-expressions as arguments", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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}
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virtual ColumnNumbers getArgumentsThatDontImplyNullableReturnType(size_t /*number_of_arguments*/) const { return {}; }
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#if USE_EMBEDDED_COMPILER
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bool isCompilable(const DataTypes & arguments) const;
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llvm::Value * compile(llvm::IRBuilderBase &, const DataTypes & arguments, ValuePlaceholders values) const;
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#endif
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protected:
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#if USE_EMBEDDED_COMPILER
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virtual bool isCompilableImpl(const DataTypes &) const { return false; }
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virtual llvm::Value * compileImpl(llvm::IRBuilderBase &, const DataTypes &, ValuePlaceholders) const
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{
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throw Exception(getName() + " is not JIT-compilable", ErrorCodes::NOT_IMPLEMENTED);
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}
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#endif
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};
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using FunctionPtr = std::shared_ptr<IFunction>;
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}
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