Support const methods (Closes #45)

Author: cinemast

include/jsonrpccxx/typemapper.hpp

@@ -197,4 +197,22 @@ namespace jsonrpccxx {
     };
     return GetHandle(function);
   }
+
+  template<typename T, typename ReturnType, typename... ParamTypes>
+  MethodHandle GetHandle(ReturnType (T::*method)(ParamTypes...) const, const T &instance)
+  {
+      std::function<ReturnType(ParamTypes...)> function = [&instance, method](ParamTypes &&...params) -> ReturnType {
+          return (instance.*method)(std::forward<ParamTypes>(params)...);
+      };
+      return GetHandle(function);
+  }
+
+  template<typename T, typename... ParamTypes>
+  NotificationHandle GetHandle(void (T::*method)(ParamTypes...) const, const T &instance)
+  {
+      std::function<void(ParamTypes...)> function = [&instance, method](ParamTypes &&...params) -> void {
+          return (instance.*method)(std::forward<ParamTypes>(params)...);
+      };
+      return GetHandle(function);
+  }
 }

test/typemapper.cpp

@@ -17,6 +17,13 @@ class SomeClass {
   void notify(const std::string &hello) { notifyResult = string("Hello world: ") + hello; }
 };
 
+class SomeClassConst {
+public:
+  int add(int a, int b) const { return a + b; } 
+  void notify(const std::string &hello) { notifyResult = string("Hello world: ") + hello; }
+};
+
+
 TEST_CASE("test function binding") {
   MethodHandle mh = GetHandle(&add);
   CHECK(mh(R"([3, 4])"_json) == 7);
@@ -40,6 +47,12 @@ TEST_CASE("test class member binding") {
   CHECK(notifyResult == "Hello world: someone");
 }
 
+TEST_CASE("test const class member binding") {
+  SomeClassConst instance;
+  MethodHandle mh = GetHandle(&SomeClassConst::add, instance);
+  CHECK(mh(R"([3, 4])"_json) == 7);
+}
+
 TEST_CASE("test class member explicit binding") {
   SomeClass instance;
   MethodHandle mh = methodHandle(&SomeClass::add, instance);