use own precious list

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: nanonext
 Type: Package
 Title: NNG (Nanomsg Next Gen) Lightweight Messaging Library
-Version: 0.13.6.9000
+Version: 0.13.6.9001
 Description: R binding for NNG (Nanomsg Next Gen), a successor to ZeroMQ. NNG is
     a socket library implementing 'Scalability Protocols', a reliable,
     high-performance standard for common communications patterns including

NEWS.md

@@ -1,4 +1,7 @@
-# nanonext 0.13.6 (development)
+# nanonext 0.13.6.9001 (development)
+
+* Integrates with the `later` package to provide the foundation for truly event-driven promises (thanks @jcheng5 for the initial prototype in #28), where side-effects are enacted upon aio request completions.
+* Adds `request_promise()` function for creating a request that may be turned into an event-driven promise.
 
 # nanonext 0.13.6
 

src/aio.c

@@ -254,15 +254,15 @@ static void request_complete_signal(void *arg) {
 
 static void release_object(void *data, Rboolean jump) {
   if (jump)
-    R_ReleaseObject((SEXP) data);
+    nano_ReleaseObject((SEXP) data);
 }
 
 static void raio_invoke_cb(void *arg) {
   SEXP call, env = (SEXP) arg;
   PROTECT(call = Rf_lcons(CADR(ATTRIB(env)), R_NilValue));
   (void) R_UnwindProtect(eval_safe, call, release_object, env, NULL);
   UNPROTECT(1);
-  R_ReleaseObject(env);
+  nano_ReleaseObject(env);
 }
 
 static void raio_complete_cb(void *arg) {
@@ -1315,7 +1315,7 @@ SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
   raio->mode = mod;
   raio->next = saio;
   if (promises) {
-    R_PreserveObject(env);
+    nano_PreserveObject(env);
     raio->cb = env;
   }
 

src/core.c

@@ -42,6 +42,30 @@ SEXP mk_error(const int xc) {
 
 }
 
+static SEXP DeleteFromList(SEXP object, SEXP list) {
+  if (CAR(list) == object) {
+    return CDR(list);
+  } else {
+    SEXP last = list;
+    for (SEXP head = CDR(list); head != R_NilValue; head = CDR(head)) {
+      if (CAR(head) == object) {
+        SETCDR(last, CDR(head));
+        return list;
+      }
+      else last = head;
+    }
+    return list;
+  }
+}
+
+void nano_PreserveObject(SEXP object) {
+  Rf_cons(object, nano_precious);
+}
+
+void nano_ReleaseObject(SEXP object) {
+  nano_precious = DeleteFromList(object, nano_precious);
+}
+
 SEXP eval_safe (void *call) {
   return Rf_eval((SEXP) call, R_GlobalEnv);
 }

src/init.c

@@ -46,6 +46,7 @@ SEXP nano_aioFuncs;
 SEXP nano_aioNFuncs;
 SEXP nano_error;
 SEXP nano_klassString;
+SEXP nano_precious;
 SEXP nano_refHook;
 SEXP nano_success;
 SEXP nano_unresolved;
@@ -94,6 +95,7 @@ static void PreserveObjects(void) {
   SET_STRING_ELT(CAR(nano_error), 0, Rf_mkChar("errorValue"));
   SET_STRING_ELT(CAR(nano_error), 1, Rf_mkChar("try-error"));
   R_PreserveObject(nano_klassString = Rf_cons(R_NilValue, R_NilValue));
+  R_PreserveObject(nano_precious = Rf_cons(R_NilValue, R_NilValue));
   R_PreserveObject(nano_refHook = Rf_list2(R_NilValue, R_NilValue));
   R_PreserveObject(nano_success = Rf_ScalarInteger(0));
   R_PreserveObject(nano_unresolved = Rf_shallow_duplicate(Rf_ScalarLogical(NA_LOGICAL)));
@@ -104,6 +106,7 @@ static void ReleaseObjects(void) {
   R_ReleaseObject(nano_unresolved);
   R_ReleaseObject(nano_success);
   R_ReleaseObject(nano_refHook);
+  R_ReleaseObject(nano_precious);
   R_ReleaseObject(nano_klassString);
   R_ReleaseObject(nano_error);
   R_ReleaseObject(nano_aioNFuncs);

src/nanonext.h

@@ -192,6 +192,8 @@ typedef struct nano_buf_s {
 
 SEXP mk_error(const int);
 SEXP mk_error_ncurl(const int);
+void nano_PreserveObject(SEXP);
+void nano_ReleaseObject(SEXP);
 SEXP eval_safe(void *);
 nano_buf nano_char_buf(const SEXP);
 SEXP nano_decode(unsigned char *, const size_t, const int);
@@ -307,6 +309,7 @@ extern SEXP nano_aioFuncs;
 extern SEXP nano_aioNFuncs;
 extern SEXP nano_error;
 extern SEXP nano_klassString;
+extern SEXP nano_precious;
 extern SEXP nano_refHook;
 extern SEXP nano_success;
 extern SEXP nano_unresolved;