Added a patch from Vitaly Stoyan

src/Functions/FunctionFactory.cpp

@@ -56,6 +56,15 @@ FunctionOverloadResolverImplPtr FunctionFactory::getImpl(
     return res;
 }
 
+std::vector<std::string> FunctionFactory::getAllNames() const {
+    std::vector<std::string> res;
+    res.reserve(functions.size());
+    for (const auto& func : functions) {
+        res.emplace_back(func.first);
+    }
+    return res;
+}
+
 FunctionOverloadResolverPtr FunctionFactory::get(
     const std::string & name,
     const Context & context) const

src/Functions/FunctionFactory.h

@@ -39,6 +39,8 @@ public:
             registerFunction(name, &Function::create, case_sensitiveness);
     }
 
+    std::vector<std::string> getAllNames() const;
+
     /// Throws an exception if not found.
     FunctionOverloadResolverPtr get(const std::string & name, const Context & context) const;