func VariableExists(name string) bool {
nameC := C.CString(name)
defer C.free(unsafe.Pointer(nameC))
return C.findVar(C.install(nameC), C.R_GlobalEnv) == C.R_UnboundValue
}
//export ListenAndServe
func ListenAndServe(addr_ C.SEXP, handler_ C.SEXP, rho_ C.SEXP) C.SEXP {
if C.TYPEOF(addr_) != C.STRSXP {
fmt.Printf("addr is not a string (STRXSP; instead it is: %d)! addr argument to ListenAndServe() must be a string of form 'ip:port'\n", C.TYPEOF(addr_))
return C.R_NilValue
}
//msglen := 0
if 0 == int(C.isFunction(handler_)) { // 0 is false
C.ReportErrorToR_NoReturn(C.CString("‘handler’ must be a function"))
return C.R_NilValue
}
if rho_ != nil && rho_ != C.R_NilValue {
if 0 == int(C.isEnvironment(rho_)) { // 0 is false
C.ReportErrorToR_NoReturn(C.CString("‘rho’ should be an environment"))
return C.R_NilValue
}
}
caddr := C.R_CHAR(C.STRING_ELT(addr_, 0))
addr := C.GoString(caddr)
fmt.Printf("ListenAndServe listening on address '%s'...\n", addr)
webSockHandler := func(w http.ResponseWriter, r *http.Request) {
if r.URL.Path != "/" {
http.Error(w, "Not found", 404)
return
}
if r.Method != "GET" {
http.Error(w, "Method not allowed, only GET allowed.", 405)
return
}
c, err := upgrader.Upgrade(w, r, nil)
if err != nil {
fmt.Print("websocket handler upgrade error:", err)
return
}
defer c.Close()
mt, message, err := c.ReadMessage()
if err != nil {
fmt.Println("read error: ", err)
return
}
// make the call, and get a response
msglen := len(message)
rawmsg := C.allocVector(C.RAWSXP, C.R_xlen_t(msglen))
C.Rf_protect(rawmsg)
C.memcpy(unsafe.Pointer(C.RAW(rawmsg)), unsafe.Pointer(&message[0]), C.size_t(msglen))
// put msg into env that handler_ is called with.
C.defineVar(C.install(C.CString("msg")), rawmsg, rho_)
R_serialize_fun = C.findVar(C.install(C.CString("serialize")), C.R_GlobalEnv)
// todo: callbacks to R functions here not working. don't really need them if R always acts as a client instead.
// evaluate
C.PrintToR(C.CString("listenAndServe: stuffed msg into env rho_.\n"))
//R_fcall := C.lang3(handler_, rawmsg, C.R_NilValue)
R_fcall := C.lang3(R_serialize_fun, rawmsg, C.R_NilValue)
C.Rf_protect(R_fcall)
C.PrintToR(C.CString("listenAndServe: got msg, just prior to eval.\n"))
evalres := C.eval(R_fcall, rho_)
C.Rf_protect(evalres)
C.PrintToR(C.CString("listenAndServe: after eval.\n"))
/*
var s, t C.SEXP
s = C.allocList(3)
t = s
C.Rf_protect(t)
C.SetTypeToLANGSXP(&s)
//C.SETCAR(t, R_fcall)
C.SETCAR(t, handler_)
t = C.CDR(t)
C.SETCAR(t, rawmsg)
evalres := C.eval(s, rho_)
C.Rf_protect(evalres)
*/
C.PrintToR(C.CString("nnListenAndServe: done with eval.\n"))
if C.TYPEOF(evalres) != C.RAWSXP {
fmt.Printf("rats! handler result was not RAWSXP raw bytes!\n")
} else {
//fmt.Printf("recv: %s\n", message)
err = c.WriteMessage(mt, message)
if err != nil {
fmt.Println("write error: ", err)
}
}
C.Rf_unprotect(3)
} // end handler func
http.HandleFunc("/", webSockHandler)
err := http.ListenAndServe(addr, nil)
if err != nil {
fmt.Println("ListenAndServe: ", err)
}
return C.R_NilValue
}