2012-12-18 20:06:36 +00:00
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#pragma once
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2017-01-14 09:00:19 +00:00
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#include <string>
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#include <memory>
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#include <unordered_map>
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2017-07-10 04:34:14 +00:00
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#include <ext/singleton.h>
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2017-08-14 04:23:38 +00:00
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2017-06-10 09:04:31 +00:00
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#include <Common/Exception.h>
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2017-08-14 04:23:38 +00:00
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#include <Core/Types.h>
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2012-12-18 20:06:36 +00:00
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namespace DB
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{
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class Context;
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2017-01-14 09:00:19 +00:00
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class IFunction;
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using FunctionPtr = std::shared_ptr<IFunction>;
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2012-12-18 20:06:36 +00:00
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2016-07-09 23:37:29 +00:00
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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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2012-12-18 20:06:36 +00:00
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*/
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2017-07-10 04:34:14 +00:00
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class FunctionFactory : public ext::singleton<FunctionFactory>
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2012-12-18 20:06:36 +00:00
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{
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2017-04-01 07:20:54 +00:00
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friend class StorageSystemFunctions;
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2015-04-24 15:49:30 +00:00
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2014-08-22 00:57:20 +00:00
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private:
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2017-06-10 09:04:31 +00:00
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using Creator = FunctionPtr(*)(const Context & context); /// Not std::function, for lower object size and less indirection.
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2017-08-14 04:23:38 +00:00
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using Functions = std::unordered_map<String, Creator>;
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2014-08-22 00:57:20 +00:00
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2017-08-14 04:23:38 +00:00
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Functions functions;
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Functions case_insensitive_functions;
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2014-08-22 00:57:20 +00:00
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2017-08-14 04:23:38 +00:00
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/// For compatibility with SQL, it's possible to specify that certain function name is case insensitive.
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enum CaseSensitiveness
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{
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CaseSensitive,
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CaseInsensitive
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};
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public:
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FunctionPtr get(const String & name, const Context & context) const; /// Throws an exception if not found.
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FunctionPtr tryGet(const String & name, const Context & context) const; /// Returns nullptr if not found.
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2014-08-22 00:57:20 +00:00
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2017-04-01 07:20:54 +00:00
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/// No locking, you must register all functions before usage of get, tryGet.
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2017-08-14 04:23:38 +00:00
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void registerFunction(const String & name, Creator creator, CaseSensitiveness case_sensitiveness = CaseSensitive);
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2017-06-10 09:04:31 +00:00
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2017-08-14 04:23:38 +00:00
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template <typename Function>
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void registerFunction()
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{
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registerFunction(String(Function::name), &Function::create);
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2017-04-01 07:20:54 +00:00
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}
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2012-12-18 20:06:36 +00:00
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};
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}
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