Add a method to ease handling the `help` command

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

examples/FocusSerial/FocusSerial.ino

@@ -45,14 +45,15 @@ class FocusTestCommand : public Plugin {
   FocusTestCommand() {}
 
   EventHandlerResult onFocusEvent(const char *command) {
-    if (strcmp_P(command, PSTR("test")) == 0) {
+    const char *cmd = PSTR("test");
+
+    if (::Focus.handleHelp(command, cmd))
+      return EventHandlerResult::OK;
+
+    if (strcmp_P(command, cmd) == 0) {
       Serial.println(F("ok!"));
       return EventHandlerResult::EVENT_CONSUMED;
     }
-    if (strcmp_P(command, PSTR("help")) == 0) {
-      Serial.println(F("test"));
-      return EventHandlerResult::OK;
-    }
 
     return EventHandlerResult::OK;
   }
@@ -63,10 +64,7 @@ class FocusHelpCommand : public Plugin {
   FocusHelpCommand() {}
 
   EventHandlerResult onFocusEvent(const char *command) {
-    if (strcmp_P(command, PSTR("help")) == 0) {
-      Serial.println(F("help"));
-      return EventHandlerResult::OK;
-    }
+    ::Focus.handleHelp(command, PSTR("help"));
 
     return EventHandlerResult::OK;
   }

src/kaleidoscope/FocusSerial.cpp

@@ -59,6 +59,15 @@ EventHandlerResult FocusSerial::beforeReportingState() {
   return EventHandlerResult::OK;
 }
 
+bool FocusSerial::handleHelp(const char *command,
+                             const char *help_message) {
+  if (strcmp_P(command, PSTR("help")) != 0)
+    return false;
+
+  Serial.println((const __FlashStringHelper *)help_message);
+  return true;
+}
+
 void FocusSerial::printSpace(void) {
   Serial.print(F(" "));
 }

src/kaleidoscope/FocusSerial.h

@@ -24,6 +24,9 @@ class FocusSerial : public kaleidoscope::Plugin {
  public:
   FocusSerial(void) {}
 
+  bool handleHelp(const char *command,
+                  const char *help_message);
+
   /* Helpers */
   static void printNumber(uint16_t number);
   static void printSpace(void);