C++ Difficulty Creating Instance of Class within Singleton Class - c++

Question

I have a fairly good template (as in snippet of code) I pull out whenever I need a singleton class. I am now trying to apply it within my project to allow me to control a single instance of a web server. I can make a web server without encasing it in my class. When I try to encase it within the class I'm apparently too unskilled to pull it off.
I've tried the obvious Googling and searching here. I've read relevant posts. I am sure this does not mean I have a unique problem, just that I've not figured out the right way to fix it. Here's what I am working with:
webserver.h:
#include <ESP8266WebServer.h>
#include <FS.h>
class WebServer {
private:
// Singleton Declarations
static bool instanceFlag;
static WebServer *single;
WebServer() {}
// Other Declarations
FS *filesystem;
ESP8266WebServer server();
String getContentType(String);
bool handleFileRead(String);
public:
// Singleton Declarations
static WebServer* getInstance();
~WebServer() {instanceFlag = false;}
// Other Declarations
void initialize(int);
void handleLoop();
};
webserver.cpp:
#include "webserver.h"
bool WebServer::instanceFlag = false;
WebServer* WebServer::single = NULL;
WebServer* WebServer::getInstance() {
if(!instanceFlag) {
single = new WebServer();
instanceFlag = true;
return single;
} else {
return single;
}
}
void WebServer::initialize (int port) {
ESP8266WebServer server(port);
FS *filesystem;
filesystem->begin();
Serial.print("Open: http://");
Serial.print(WiFi.hostname().c_str());
Serial.println(".local");
server.onNotFound([]() {
if (!single->handleFileRead(single->server.uri())) {
single->server.send(404, "text/plain", "404: File not found.");
}
});
server.begin();
Serial.print("HTTP server started on port ");
Serial.print(port);
Serial.println(".");
}
String WebServer::getContentType(String filename) {
if (single->server.hasArg("download")) {
return "application/octet-stream";
} else if (filename.endsWith(".htm")) {
return "text/html";
} else if (filename.endsWith(".html")) {
return "text/html";
} else if (filename.endsWith(".css")) {
return "text/css";
} else if (filename.endsWith(".js")) {
return "application/javascript";
} else if (filename.endsWith(".png")) {
return "image/png";
} else if (filename.endsWith(".gif")) {
return "image/gif";
} else if (filename.endsWith(".jpg")) {
return "image/jpeg";
} else if (filename.endsWith(".ico")) {
return "image/x-icon";
} else if (filename.endsWith(".xml")) {
return "text/xml";
} else if (filename.endsWith(".pdf")) {
return "application/x-pdf";
} else if (filename.endsWith(".zip")) {
return "application/x-zip";
} else if (filename.endsWith(".gz")) {
return "application/x-gzip";
} else {
return "text/plain";
}
}
bool WebServer::handleFileRead(String path) {
Serial.println("handleFileRead: " + path);
if (path.endsWith("/")) {
path += "index.htm";
}
String contentType = getContentType(path);
String pathWithGz = path + ".gz";
if (filesystem->exists(pathWithGz) || filesystem->exists(path)) {
if (filesystem->exists(pathWithGz)) {
path += ".gz";
}
File file = filesystem->open(path, "r");
single->server.streamFile(file, contentType);
file.close();
return true;
}
return false;
}
void WebServer::handleLoop() {
single->server.handleClient();
}
The errors I am getting are all similar to the following:
src\webserver.cpp: In member function 'bool WebServer::handleFileRead(String)':
src\webserver.cpp:81:23: error: 'WebServer::single->WebServer::server' does not have class type
single->server.streamFile(file, contentType);
I get the idea of "does not have a class type", I just have no idea what it means here. In my mind, "single" is a pointer to the class so I'm unclear what that reference is not working.
Obviously, there are ample examples out there how to do a web server without encapsulating it. Other things I need to do for this project lend itself to creating that requirement.

Answer 1

There are some mistake in your code.
In webserver.h:
...
private:
// Singleton Declarations
static bool instanceFlag;
static WebServer *single;
WebServer() {}
// Other Declarations
FS *filesystem;
ESP8266WebServer *server; // <--- remove the parentheses and make it a pointer
String getContentType(String);
bool handleFileRead(String);
...
In webserver.cpp:
In WebServer::initialize I am guessing you want to initialize the class server and filesystem not locals, so it should probably look like this:
void WebServer::initialize (int port) {
server = new ESP8266WebServer(port);
filesystem = new FS();
...
}
And now everywhere you use the server you have to use the -> operator.
For example:
void WebServer::handleLoop() {
single->server->handleClient();
}
Please keep in mind that server and filesystem objects have to be deleted to avoid memory leaks.
EDIT:
You get the new error because FS has no constructor without arguments.
FS's constructor looks like this: FS(FSImplPtr impl) : _impl(impl) { }, here you can see that FSImplPtr is a typedef for std::shared_ptr<FileImpl>, so you need to provide this as a parameter.
It works your way, because SPIFFS's existence is declared here and is of type FS.
If you want to use SPIFFS, you have to use it like this: filesystem = &SPIFFS;, not like you mentioned in the comments (FS* filesystem = &SPIFFS;) because your way creates a new temporary variable named filesystem, and probably you expect to initiate the filesystem in the class, not a local one.