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#pragma once
#include <Interpreters/Context_fwd.h>
#include <Common/register_objects.h>
#include <Common/IFactoryWithAliases.h>
#include <Common/FunctionDocumentation.h>
#include <Functions/IFunction.h>
#include <Functions/IFunctionAdaptors.h>
#include <functional>
#include <memory>
#include <string>
#include <unordered_map>
namespace DB
{
using FunctionCreator = std::function<FunctionOverloadResolverPtr(ContextPtr)>;
using FunctionFactoryData = std::pair<FunctionCreator, FunctionDocumentation>;
/** Creates function by name.
* The provided Context is guaranteed to outlive the created function. Functions may use it for
* things like settings, current database, permission checks, etc.
*/
class FunctionFactory : private boost::noncopyable, public IFactoryWithAliases<FunctionFactoryData>
{
public:
static FunctionFactory & instance();
template <typename Function>
void registerFunction(FunctionDocumentation doc = {}, CaseSensitiveness case_sensitiveness = CaseSensitive)
{
registerFunction<Function>(Function::name, std::move(doc), case_sensitiveness);
}
template <typename Function>
void registerFunction(const std::string & name, FunctionDocumentation doc = {}, CaseSensitiveness case_sensitiveness = CaseSensitive)
{
if constexpr (std::is_base_of_v<IFunction, Function>)
registerFunction(name, &adaptFunctionToOverloadResolver<Function>, std::move(doc), case_sensitiveness);
else
registerFunction(name, &Function::create, std::move(doc), case_sensitiveness);
}
/// This function is used by YQL - innovative transactional DBMS that depends on ClickHouse by source code.
std::vector<std::string> getAllNames() const;
bool has(const std::string & name) const;
/// Throws an exception if not found.
FunctionOverloadResolverPtr get(const std::string & name, ContextPtr context) const;
/// Returns nullptr if not found.
FunctionOverloadResolverPtr tryGet(const std::string & name, ContextPtr context) const;
/// The same methods to get developer interface implementation.
FunctionOverloadResolverPtr getImpl(const std::string & name, ContextPtr context) const;
FunctionOverloadResolverPtr tryGetImpl(const std::string & name, ContextPtr context) const;
/// Register a function by its name.
/// No locking, you must register all functions before usage of get.
void registerFunction(
const std::string & name,
FunctionCreator creator,
FunctionDocumentation doc = {},
CaseSensitiveness case_sensitiveness = CaseSensitive);
FunctionDocumentation getDocumentation(const std::string & name) const;
private:
using Functions = std::unordered_map<std::string, Value>;
Functions functions;
Functions case_insensitive_functions;
template <typename Function>
static FunctionOverloadResolverPtr adaptFunctionToOverloadResolver(ContextPtr context)
{
return std::make_unique<FunctionToOverloadResolverAdaptor>(Function::create(context));
}
const Functions & getMap() const override { return functions; }
const Functions & getCaseInsensitiveMap() const override { return case_insensitive_functions; }
String getFactoryName() const override { return "FunctionFactory"; }
};
const String & getFunctionCanonicalNameIfAny(const String & name);
}
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