binding-wrap: Rework of context handling

The C++ wrapper for handling contexts has
to be improved. This is a proposition of
improvement.

Change-Id: I7df36383f427d109356bdf4df573cba4b6e6ec05
Signed-off-by: Jose Bollo <jose.bollo@iot.bzh>

2 files changed, 72 insertions, 33 deletions

diff --git a/bindings/tutorials/tuto-3.cpp b/bindings/tutorials/tuto-3.cpp
index 8ad69ef3..a257999b 100644
--- a/bindings/tutorials/tuto-3.cpp
+++ b/bindings/tutorials/tuto-3.cpp
@@ -1,3 +1,5 @@
+#include <string>
+
 #include <string.h>
 #include <json-c/json.h>
 
@@ -6,10 +8,20 @@
 
 afb::event event_login, event_logout;
 
+class session
+{
+private:
+	std::string user_;
+public:
+	session(const char *user) : user_(user) {}
+	~session() {}
+	operator const char *() const { return user_.c_str(); }
+};
+
 void login(afb::req req)
 {
 	json_object *args, *user, *passwd;
-	char *usr;
+	const char *usr;
 
 	args = req.json();
 	if (!json_object_object_get_ex(args, "user", &user)
@@ -23,10 +35,10 @@ void login(afb::req req)
 		AFB_REQ_ERROR(req, "login, unauthorized: %s", json_object_get_string(args));
 		req.fail("unauthorized");
 	} else {
-		usr = strdup(json_object_get_string(user));
+		usr = json_object_get_string(user);
 		AFB_REQ_NOTICE(req, "login user: %s", usr);
+		req.context<session>().set(new session(usr));
 		req.session_set_LOA(1);
-//		req.context(1, nullptr, free, usr);
 		req.success();
 		event_login.push(json_object_new_string(usr));
 	}
@@ -35,19 +47,17 @@ void login(afb::req req)
 void action(afb::req req)
 {
 	json_object *args, *val;
-	char *usr;
+	session &usr = req.context<session>();
 
 	args = req.json();
-//	usr = (char*)req.context_get();
-usr = nullptr;
-	AFB_REQ_NOTICE(req, "action for user %s: %s", usr, json_object_get_string(args));
+	AFB_REQ_NOTICE(req, "action for user %s: %s", (const char*)usr, json_object_get_string(args));
 	if (json_object_object_get_ex(args, "subscribe", &val)) {
 		if (json_object_get_boolean(val)) {
-			AFB_REQ_NOTICE(req, "user %s subscribes to events", usr);
+			AFB_REQ_NOTICE(req, "user %s subscribes to events", (const char*)usr);
 			req.subscribe(event_login);
 			req.subscribe(event_logout);
 		} else {
-			AFB_REQ_NOTICE(req, "user %s unsubscribes to events", usr);
+			AFB_REQ_NOTICE(req, "user %s unsubscribes to events", (const char*)usr);
 			req.unsubscribe(event_login);
 			req.unsubscribe(event_logout);
 		}
@@ -57,22 +67,16 @@ usr = nullptr;
 
 void logout(afb::req req)
 {
-	char *usr;
+	session &usr = req.context<session>();
 
-//	usr = (char*)req.context_get();
-usr = nullptr;
-	AFB_REQ_NOTICE(req, "login user %s out", usr);
-	event_logout.push(json_object_new_string(usr));
+	AFB_REQ_NOTICE(req, "login user %s out", (const char*)usr);
+	event_logout.push(json_object_new_string((const char*)usr));
 	req.session_set_LOA(0);
-//	req.context_clear();
+	req.context<session>().clear();
 	req.success();
 }
 
-int init(
-#if AFB_BINDING_VERSION >= 3
-	afb_api_t api
-#endif
-)
+int init(afb_api_t api)
 {
 	AFB_NOTICE("init");
 	event_login = afb_daemon_make_event("login");
@@ -92,4 +96,3 @@ const afb_verb_t verbs[] = {
 
 const afb_binding_t afbBindingExport = afb::binding("tuto-3", verbs, "third tutorial: C++", init);
 
-
diff --git a/include/afb/c++/binding-wrap.hpp b/include/afb/c++/binding-wrap.hpp
index a23e5537..6af3f845 100644
--- a/include/afb/c++/binding-wrap.hpp
+++ b/include/afb/c++/binding-wrap.hpp
@@ -258,8 +258,6 @@ public:
 	void failf(const char *error, const char *info, ...) const;
 	void failv(const char *error, const char *info, va_list args) const;
 
-	template < class T > T *context() const;
-
 	void addref() const;
 
 	void unref() const;
@@ -294,6 +292,54 @@ public:
 	int get_uid() const;
 
 	json_object *get_client_info() const;
+
+	template < class T = void >
+	class contextclass {
+
+		friend class req;
+		afb_req_t req_;
+		contextclass(afb_req_t r) : req_(r) {}
+
+	public:
+		inline operator T *() const { return get(); }
+		inline operator T &() const { return *get(); }
+		inline T* get() const {
+			return reinterpret_cast<T*>(
+				afb_req_context(req_, 0,
+					nullptr,
+					nullptr,
+					nullptr));
+		}
+
+		inline void set(T *value, void (*destroyer)(T*) = [](T*t){delete t;}) const {
+			afb_req_context(req_, 1,
+				nullptr,
+				reinterpret_cast<void(*)(void*)>(destroyer),
+				reinterpret_cast<void*>(value));
+		}
+
+		inline void unset() { set(nullptr); }
+		inline void clear() { set(nullptr); }
+
+		inline T *lazy(T *(*allocator)() = []()->T*{return new T();}, void (*destroyer)(T*) = [](T*t){delete t;}) const {
+			return reinterpret_cast<T*>(
+				afb_req_context(req_, 0,
+					[allocator](void*)->T*{return allocator();},
+					reinterpret_cast<void(*)(void*)>(destroyer),
+					nullptr));
+		}
+
+		template <class I>
+		inline T *lazy(I *i, T *(*allocator)(I*) = [](I*i)->T*{return new T(i);}, void (*destroyer)(T*) = [](T*t){delete t;}) const {
+			return reinterpret_cast<T*>(
+				afb_req_context(req_, 0,
+					[allocator](void*i)->T*{return allocator(reinterpret_cast<I*>(i));},
+					reinterpret_cast<void(*)(void*)>(destroyer),
+					reinterpret_cast<void*>(i)));
+		}
+	};
+
+	template < class T > contextclass<T> context() const { return contextclass<T>(req_); }
 };
 
 /*************************************************************************/
@@ -476,16 +522,6 @@ inline void req::failf(const char *error, const char *info, ...) const
 	va_end(args);
 }
 
-template < class T >
-inline T *req::context() const
-{
-	T* (*creater)(void*) = [](){return new T();};
-	void (*freer)(T*) = [](T*t){delete t;};
-	return reinterpret_cast<T*>(afb_req_context(req_, 0,
-			reinterpret_cast<void *(*)(void*)>(creater),
-			reinterpret_cast<void (*)(void*)>(freer), nullptr));
-}
-
 inline void req::addref() const { afb_req_addref(req_); }
 
 inline void req::unref() const { afb_req_unref(req_); }