there is the function : decodeURLComponent ,why not encodeURLComponent?

namespace DB
{
class FunctionFactory;
void registerFunctionProtocol(FunctionFactory & factory);
void registerFunctionDomain(FunctionFactory & factory);
void registerFunctionDomainWithoutWWW(FunctionFactory & factory);
void registerFunctionFirstSignificantSubdomain(FunctionFactory & factory);
void registerFunctionFirstSignificantSubdomainCustom(FunctionFactory & factory);
void registerFunctionTopLevelDomain(FunctionFactory & factory);
void registerFunctionPort(FunctionFactory & factory);
void registerFunctionPath(FunctionFactory & factory);
void registerFunctionPathFull(FunctionFactory & factory);
void registerFunctionQueryString(FunctionFactory & factory);
void registerFunctionFragment(FunctionFactory & factory);
void registerFunctionQueryStringAndFragment(FunctionFactory & factory);
void registerFunctionExtractURLParameter(FunctionFactory & factory);
void registerFunctionExtractURLParameters(FunctionFactory & factory);
void registerFunctionExtractURLParameterNames(FunctionFactory & factory);
void registerFunctionURLHierarchy(FunctionFactory & factory);
void registerFunctionURLPathHierarchy(FunctionFactory & factory);
void registerFunctionCutToFirstSignificantSubdomain(FunctionFactory & factory);
void registerFunctionCutToFirstSignificantSubdomainCustom(FunctionFactory & factory);
void registerFunctionCutWWW(FunctionFactory & factory);
void registerFunctionCutQueryString(FunctionFactory & factory);
void registerFunctionCutFragment(FunctionFactory & factory);
void registerFunctionCutQueryStringAndFragment(FunctionFactory & factory);
void registerFunctionCutURLParameter(FunctionFactory & factory);
void registerFunctionDecodeURLComponent(FunctionFactory & factory);
void registerFunctionNetloc(FunctionFactory & factory);
void registerFunctionsURL(FunctionFactory & factory)