Adds generate_hints=true for dropping hints in response, resolves #1789.

Adds an `generate_hints=false` option which lets us skip generating and
emitting hints for Waypoints. This can be used to decrease the response
size when the user does not need hints anyway.

We should think about making `false` the default here in v6.

include/engine/api/base_api.hpp

@@ -44,13 +44,19 @@ class BaseAPI
         return waypoints;
     }
 
-    // FIXME gcc 4.8 doesn't support for lambdas to call protected member functions
-    //  protected:
+  protected:
     util::json::Object MakeWaypoint(const PhantomNode &phantom) const
     {
-        return json::makeWaypoint(phantom.location,
-                                  facade.GetNameForID(phantom.name_id),
-                                  Hint{phantom, facade.GetCheckSum()});
+        if (parameters.generate_hints)
+        {
+            return json::makeWaypoint(phantom.location,
+                                      facade.GetNameForID(phantom.name_id),
+                                      Hint{phantom, facade.GetCheckSum()});
+        }
+        else
+        {
+            return json::makeWaypoint(phantom.location, facade.GetNameForID(phantom.name_id));
+        }
     }
 
     const datafacade::BaseDataFacade &facade;

include/engine/api/base_parameters.hpp

@@ -66,6 +66,9 @@ struct BaseParameters
     std::vector<boost::optional<double>> radiuses;
     std::vector<boost::optional<Bearing>> bearings;
 
+    // Adds hints to response which can be included in subsequent requests, see `hints` above.
+    bool generate_hints = true;
+
     // FIXME add validation for invalid bearing values
     bool IsValid() const
     {

include/engine/api/json_factory.hpp

@@ -89,6 +89,10 @@ util::json::Object makeRoute(const guidance::Route &route,
                              util::json::Array legs,
                              boost::optional<util::json::Value> geometry);
 
+// Creates a Waypoint without Hint, see the Hint overload below
+util::json::Object makeWaypoint(const util::Coordinate location, std::string name);
+
+// Creates a Waypoint with Hint, see the overload above when Hint is not needed
 util::json::Object
 makeWaypoint(const util::Coordinate location, std::string name, const Hint &hint);
 

include/engine/api/match_api.hpp

@@ -48,9 +48,7 @@ class MatchAPI final : public RouteAPI
         response.values["code"] = "Ok";
     }
 
-    // FIXME gcc 4.8 doesn't support for lambdas to call protected member functions
-    //  protected:
-
+  protected:
     // FIXME this logic is a little backwards. We should change the output format of the
     // map_matching
     // routing algorithm to be easier to consume here.

include/engine/api/route_api.hpp

@@ -61,8 +61,7 @@ class RouteAPI : public BaseAPI
         response.values["code"] = "Ok";
     }
 
-    // FIXME gcc 4.8 doesn't support for lambdas to call protected member functions
-    //  protected:
+  protected:
     template <typename ForwardIter>
     util::json::Value MakeGeometry(ForwardIter begin, ForwardIter end) const
     {

include/engine/api/table_api.hpp

@@ -70,8 +70,7 @@ class TableAPI final : public BaseAPI
         response.values["code"] = "Ok";
     }
 
-    // FIXME gcc 4.8 doesn't support for lambdas to call protected member functions
-    //  protected:
+  protected:
     virtual util::json::Array MakeWaypoints(const std::vector<PhantomNode> &phantoms) const
     {
         util::json::Array json_waypoints;

include/engine/api/trip_api.hpp

@@ -47,9 +47,7 @@ class TripAPI final : public RouteAPI
         response.values["code"] = "Ok";
     }
 
-    // FIXME gcc 4.8 doesn't support for lambdas to call protected member functions
-    //  protected:
-
+  protected:
     // FIXME this logic is a little backwards. We should change the output format of the
     // trip plugin routing algorithm to be easier to consume here.
     util::json::Array MakeWaypoints(const std::vector<std::vector<NodeID>> &sub_trips,

include/server/api/base_parameters_grammar.hpp

@@ -141,11 +141,18 @@ struct BaseParametersGrammar : boost::spirit::qi::grammar<Iterator, Signature>
                          add_hint, qi::_r1, qi::_1)] %
                          ';';
 
+        generate_hints_rule =
+            qi::lit("generate_hints=") >
+            qi::bool_[ph::bind(&engine::api::BaseParameters::generate_hints, qi::_r1) = qi::_1];
+
         bearings_rule =
             qi::lit("bearings=") >
             (-(qi::short_ > ',' > qi::short_))[ph::bind(add_bearing, qi::_r1, qi::_1)] % ';';
 
-        base_rule = radiuses_rule(qi::_r1) | hints_rule(qi::_r1) | bearings_rule(qi::_r1);
+        base_rule = radiuses_rule(qi::_r1)   //
+                    | hints_rule(qi::_r1)    //
+                    | bearings_rule(qi::_r1) //
+                    | generate_hints_rule(qi::_r1);
     }
 
   protected:
@@ -157,6 +164,8 @@ struct BaseParametersGrammar : boost::spirit::qi::grammar<Iterator, Signature>
     qi::rule<Iterator, Signature> radiuses_rule;
     qi::rule<Iterator, Signature> hints_rule;
 
+    qi::rule<Iterator, Signature> generate_hints_rule;
+
     qi::rule<Iterator, osrm::engine::Bearing()> bearing_rule;
     qi::rule<Iterator, osrm::util::Coordinate()> location_rule;
     qi::rule<Iterator, std::vector<osrm::util::Coordinate>()> polyline_rule;