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80 lines
2.6 KiB
C++
80 lines
2.6 KiB
C++
#pragma once
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#include <Functions/IFunctionAdaptors.h>
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#include <Common/IFactoryWithAliases.h>
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#include <functional>
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#include <memory>
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#include <string>
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#include <unordered_map>
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namespace DB
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{
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class Context;
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/** Creates function by name.
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* Function could use for initialization (take ownership of shared_ptr, for example)
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* some dictionaries from Context.
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*/
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class FunctionFactory : private boost::noncopyable, public IFactoryWithAliases<std::function<FunctionOverloadResolverImplPtr(const Context &)>>
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{
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public:
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static FunctionFactory & instance();
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template <typename Function>
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void registerFunction(CaseSensitiveness case_sensitiveness = CaseSensitive)
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{
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registerFunction<Function>(Function::name, case_sensitiveness);
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}
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template <typename Function>
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void registerFunction(const std::string & name, CaseSensitiveness case_sensitiveness = CaseSensitive)
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{
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if constexpr (std::is_base_of<IFunction, Function>::value)
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registerFunction(name, &createDefaultFunction<Function>, case_sensitiveness);
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else
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registerFunction(name, &Function::create, case_sensitiveness);
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}
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/// Throws an exception if not found.
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FunctionOverloadResolverPtr get(const std::string & name, const Context & context) const;
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/// Returns nullptr if not found.
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FunctionOverloadResolverPtr tryGet(const std::string & name, const Context & context) const;
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/// The same methods to get developer interface implementation.
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FunctionOverloadResolverImplPtr getImpl(const std::string & name, const Context & context) const;
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FunctionOverloadResolverImplPtr tryGetImpl(const std::string & name, const Context & context) const;
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private:
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using Functions = std::unordered_map<std::string, Creator>;
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Functions functions;
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Functions case_insensitive_functions;
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template <typename Function>
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static FunctionOverloadResolverImplPtr createDefaultFunction(const Context & context)
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{
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return std::make_unique<DefaultOverloadResolver>(Function::create(context));
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}
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const Functions & getCreatorMap() const override { return functions; }
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const Functions & getCaseInsensitiveCreatorMap() const override { return case_insensitive_functions; }
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String getFactoryName() const override { return "FunctionFactory"; }
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/// Register a function by its name.
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/// No locking, you must register all functions before usage of get.
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void registerFunction(
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const std::string & name,
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Creator creator,
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CaseSensitiveness case_sensitiveness = CaseSensitive);
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};
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}
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