codestyle

src/main.cpp

@@ -9,73 +9,55 @@
 /*
  * Adds two integers
  */
-int add(int a, int b) {
-  int res;
-  bool overflow = __builtin_sadd_overflow(a, b, &res);
-  if (overflow) {
-    throw std::invalid_argument("Malformed input. Integer overflow (add).");
-  }
-  return res;
+int add(const int a, const int b) {
+  return a + b;
 }
 
 /*
- * Multiplies two integers
+ * Subtracts integer b from integer a
  */
-int multiply(int a, int b) {
-  int res;
-  bool overflow = __builtin_smul_overflow(a, b, &res);
-  if (overflow) {
-    throw std::invalid_argument("Malformed input. Multiplication error.");
-  }
-  return res;
+int subtract(const int a, const int b) {
+  return b - a;
 }
 
 /*
- * Subtracts integer b from integer a
+ * Multiplies two integers
  */
-int subtract(int a, int b) {
-  int res;
-  bool overflow = __builtin_ssub_overflow(b, a, &res);
-  if (overflow) {
-    throw std::invalid_argument("Malformed input. Integer overflow (subtract).");
-  }
-  return res;
+int multiply(const int a, const int b) {
+  return a * b;
 }
 
 /*
  * Divides integer b from integer a, throwing an exception when b is zero.
  * Throws an std::invalid_argument exceptions if invalid parameters are provided.
  */
-int divide(int a, int b) {
+int divide(const int a, const int b) {
   if (b == 0) {
-    throw std::invalid_argument("Malformed input. Division by zero.");
+    throw std::invalid_argument("Tried to divide by 0.");
   }
   return a / b;
 }
 
 using binary_operator = decltype(&add);
 
-std::unordered_map<char, binary_operator> map {
-  {'+', add},
-  {'-', subtract},
-  {'*', multiply},
-  {'/', divide}
-};
-
 int evaluate(const std::string &s) {
-  int a, b;
-  decltype(map)::iterator iter;
   std::stack<int> stack;
-
+  static const std::unordered_map<char, binary_operator> map {
+    {'+', add},
+    {'-', subtract},
+    {'*', multiply},
+    {'/', divide}
+  };
+  decltype(map)::iterator iter;
   for (char c : s) {
     if (std::isdigit(c)) {
       stack.push(c - '0');
     } else if (stack.size() >= 2 ) {
         iter = map.find(c);
         if (iter != map.end()) {
-          a = stack.top();
+          const auto a = stack.top();
           stack.pop();
-          b = stack.top();
+          const auto b = stack.top();
           stack.pop();
           stack.push(iter->second(b, a));
         } else {
@@ -109,8 +91,8 @@ int main() {
   } catch (const std::exception &e) {
     std::cout << e.what();
   }
+
   if (result != INT_MAX) {
     std::cout << "Result is: " << result << '\n';
   }
-
 }