From 48008cdc6e96796718d09fd41734bfa56745f9fe Mon Sep 17 00:00:00 2001
From: "Daniel J. Hofmann" <daniel@trvx.org>
Date: Wed, 17 Feb 2016 15:10:49 -0800
Subject: [PATCH] Enforce parameter and grammar type to catch subtle bugs

---
 include/server/api/parameters_parser.hpp |  1 +
 src/server/api/parameters_parser.cpp     | 16 ++++++++++------
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/server/api/parameters_parser.hpp b/include/server/api/parameters_parser.hpp
index 548f48aab..dc990edd4 100644
--- a/include/server/api/parameters_parser.hpp
+++ b/include/server/api/parameters_parser.hpp
@@ -21,6 +21,7 @@ namespace api
 namespace detail
 {
 template <typename T> using is_parameter_t = std::is_base_of<engine::api::BaseParameters, T>;
+template <typename T> using is_grammar_t = std::is_base_of<BaseParametersGrammar, T>;
 } // ns detail
 
 // Starts parsing and iter and modifies it until iter == end or parsing failed
diff --git a/src/server/api/parameters_parser.cpp b/src/server/api/parameters_parser.cpp
index c636659f7..435e34fc8 100644
--- a/src/server/api/parameters_parser.cpp
+++ b/src/server/api/parameters_parser.cpp
@@ -18,7 +18,10 @@ namespace api
 namespace detail
 {
 
-template <typename ParameterT, typename GrammarT>
+template <typename ParameterT,
+          typename GrammarT,
+          typename std::enable_if<detail::is_parameter_t<ParameterT>::value, int>::type = 0,
+          typename std::enable_if<detail::is_grammar_t<ParameterT>::value, int>::type = 0>
 boost::optional<ParameterT> parseParameters(std::string::iterator &iter, std::string::iterator end)
 {
     GrammarT grammar;
@@ -54,18 +57,19 @@ boost::optional<engine::api::NearestParameters> parseParameters(std::string::ite
                                                                                              end);
 }
 
-//template <>
-//boost::optional<engine::api::TripParameters> parseParameters(std::string::iterator &iter,
+// template <>
+// boost::optional<engine::api::TripParameters> parseParameters(std::string::iterator &iter,
 //                                                             std::string::iterator end)
 //{
 //    return detail::parseParameters<engine::api::TripParameters, TripParametersGrammar>(iter, end);
 //}
 //
-//template <>
-//boost::optional<engine::api::MatchParameters> parseParameters(std::string::iterator &iter,
+// template <>
+// boost::optional<engine::api::MatchParameters> parseParameters(std::string::iterator &iter,
 //                                                              std::string::iterator end)
 //{
-//    return detail::parseParameters<engine::api::MatchParameters, MatchParametersGrammar>(iter, end);
+//    return detail::parseParameters<engine::api::MatchParameters, MatchParametersGrammar>(iter,
+//    end);
 //}
 
 } // ns api