generic key handlers

src/gribmessage.cpp

@@ -12,8 +12,8 @@
 #include "gribmessage.hpp"
 #include "arrowutils.hpp"
 #include "exceptions/gribexception.hpp"
-
-
+#include <type_traits>
+#include <limits>
 
 using namespace std;
 
@@ -309,6 +309,49 @@ using namespace std;
  return ret == 0 ? parameterId : defaultValue;
  }
 
+ template <typename T> 
+ T GribMessage::tryGetParameter(string parameterName, T defaultValue) {
+
+ if constexpr (std::is_floating_point_v<T>) {
+ return getDoubleParameterOrDefault(parameterName, defaultValue);
+ } 
+
+ if constexpr (std::is_integral_v<T>) {
+ return getNumericParameterOrDefault(parameterName, defaultValue);
+ }
+
+ getStringParameterOrDefault(parameterName, defaultValue);
+
+ }
+
+ template <typename T> 
+ T GribMessage::tryGetKey(string parameterName) {
+
+ auto dblDefault = std::nan("");
+ long maxLong {std::numeric_limits<long>::max()};
+ auto stringDefault = "InTheBlueRidgeMountainsOfViriginaOnTheTrailOfTheLonesomePine";
+
+ auto doubleResult = getDoubleParameterOrDefault(parameterName, dblDefault);
+ if (doubleResult != dblDefault) {
+ //we got the result
+ return doubleResult;
+ }
+ //it wasn't a double or the key doesn't exist
+ auto longResult = getNumericParameterOrDefault(parameterName, maxLong);
+ if (longResult != maxLong) {
+ //we got the result
+ return longResult;
+ }
+
+ auto stringResult = getStringParameterOrDefault(parameterName, stringDefault);
+ if (stringResult != stringDefault) {
+ return stringResult;
+ }
+
+ return nullptr;
+
+ }
+
  double GribMessage::getDoubleParameter(string parameterName) {
  double parameterId;
  auto err = codes_get_double(h, parameterName.c_str(), &parameterId);

src/gribmessage.hpp

@@ -66,6 +66,13 @@ class GribMessage
  long getNumericParameterOrDefault(string parameterName, long defaultValue = -9999);
  double getDoubleParameterOrDefault(string parameterName, double defaultValue = std::nan(""));
  string getStringParameterOrDefault(string parameterName, string defaultValue = "");
+
+ template <typename T> 
+ T tryGetParameter(string parameterName, T defaultValue = nullptr);
+
+ template <typename T> 
+ T tryGetKey(string parameterName);
+
  std::shared_ptr<arrow::Table> getData();
  std::shared_ptr<arrow::Table> getDataWithLocations();
  ~ GribMessage();