Merge pull request open-source-parsers#593 from AlB80/master

Optimize Value::isIntegral() method

src/lib_json/json_value.cpp

@@ -1360,11 +1360,23 @@ bool Value::isUInt64() const {
 }
 
 bool Value::isIntegral() const {
+  switch (type_) {
+    case intValue:
+    case uintValue:
+      return true;
+    case realValue:
 #if defined(JSON_HAS_INT64)
-  return isInt64() || isUInt64();
+      // Note that maxUInt64 (= 2^64 - 1) is not exactly representable as a
+      // double, so double(maxUInt64) will be rounded up to 2^64. Therefore we
+      // require the value to be strictly less than the limit.
+      return value_.real_ >= double(minInt64) && value_.real_ < maxUInt64AsDouble && IsIntegral(value_.real_);
 #else
-  return isInt() || isUInt();
-#endif
+      return value_.real_ >= minInt && value_.real_ <= maxUInt && IsIntegral(value_.real_);
+#endif // JSON_HAS_INT64
+    default:
+      break;
+  }
+  return false;
 }
 
 bool Value::isDouble() const { return type_ == intValue || type_ == uintValue || type_ == realValue; }