Merge branch 'master' into 'master'

Simplified parsing logic

See merge request jg943598/rpn_calculator!6

main.cpp

@@ -55,8 +55,7 @@ int evaluate(const std::string &s) {
   for (char c : s) {
     if (std::isdigit(c)) {
       stack.push(c - '0');
-    } else {
-      if (stack.size() >= 2 ) {
+    } else if (stack.size() >= 2 ) {
         iter = map.find(c);
         if (iter != map.end()) {
           a = stack.top();
@@ -67,9 +66,8 @@ int evaluate(const std::string &s) {
         } else {
           throw std::invalid_argument("Invalid character found.");
         }
-      } else {
-        throw std::invalid_argument("Invalid number of digits.");
-      }
+    } else {
+      throw std::invalid_argument("Invalid number of digits.");
     }
   }
   if (stack.size() > 1 || stack.size() == 0) {