ClickHouse/dbms/src/Functions/FunctionFactory.cpp

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#include <Functions/FunctionFactory.h>
#include <Interpreters/Context.h>
#include <Common/Exception.h>
#include <Poco/String.h>
namespace DB
{
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namespace ErrorCodes
{
extern const int UNKNOWN_FUNCTION;
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extern const int LOGICAL_ERROR;
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}
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void FunctionFactory::registerFunction(const
std::string & name,
Creator creator,
CaseSensitiveness case_sensitiveness)
{
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if (!functions.emplace(name, creator).second)
throw Exception("FunctionFactory: the function name '" + name + "' is not unique",
ErrorCodes::LOGICAL_ERROR);
if (case_sensitiveness == CaseInsensitive
&& !case_insensitive_functions.emplace(Poco::toLower(name), creator).second)
throw Exception("FunctionFactory: the case insensitive function name '" + name + "' is not unique",
ErrorCodes::LOGICAL_ERROR);
}
FunctionPtr FunctionFactory::get(
const std::string & name,
const Context & context) const
{
auto res = tryGet(name, context);
if (!res)
throw Exception("Unknown function " + name, ErrorCodes::UNKNOWN_FUNCTION);
return res;
}
FunctionPtr FunctionFactory::tryGet(
const std::string & name,
const Context & context) const
{
auto it = functions.find(name);
if (functions.end() != it)
return it->second(context);
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it = case_insensitive_functions.find(Poco::toLower(name));
if (case_insensitive_functions.end() != it)
return it->second(context);
return {};
}
}