Added parsing of exptime and period from master files (#256)

- New aare:to_string/string_to similar to what we have in
slsDetectorPackage
- Added members period and exptime to RawMasterFile
- Parsing exposure time and period for json and raw master file formats
- Parsing of RawMasterFile from string stream to enable test without
files

Comments:

- to_string is at the moment not a public header. Can make it later if
needed. This gives us full freedom with the API
- FileConfig should probably be deprecated need to look into it.
Meanwhile removed python bindings and string conv

src/to_string.hpp

@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: MPL-2.0
+
+/*
+ *The file to_string.hpp contains conversion to and from string for various aare
+ * types. It is intentionally not a part of the public API.
+ * Only include the conversion that are actually needed!!!
+ */
+
+#include "aare/defs.hpp" //enums
+
+#include <chrono> //time conversions
+
+namespace aare {
+
+
+std::string remove_unit(std::string &str);
+
+template <typename T>
+T string_to(const std::string &t, const std::string &unit) {
+    double tval{0};
+    try {
+        tval = std::stod(t);
+    } catch (const std::invalid_argument &e) {
+        throw std::runtime_error("Could not convert string to time");
+    }
+
+    using std::chrono::duration;
+    using std::chrono::duration_cast;
+    if (unit == "ns") {
+        return duration_cast<T>(duration<double, std::nano>(tval));
+    } else if (unit == "us") {
+        return duration_cast<T>(duration<double, std::micro>(tval));
+    } else if (unit == "ms") {
+        return duration_cast<T>(duration<double, std::milli>(tval));
+    } else if (unit == "s" || unit.empty()) {
+        return duration_cast<T>(std::chrono::duration<double>(tval));
+    } else {
+        throw std::runtime_error(
+            "Invalid unit in conversion from string to std::chrono::duration");
+    }
+}
+
+
+// if T has a constructor that takes a string, lets use it.
+// template <class T> T string_to(const std::string &arg) { return T{arg}; }
+template <typename T> T string_to(const std::string &arg) {
+    std::string tmp{arg};
+    auto unit = remove_unit(tmp);
+    return string_to<T>(tmp, unit);
+}
+
+/**
+ * @brief Convert a string to DetectorType
+ * @param name string representation of the DetectorType
+ * @return DetectorType
+ * @throw runtime_error if the string does not match any DetectorType
+ */
+template <> DetectorType string_to(const std::string &arg);
+
+/**
+ * @brief Convert a string to TimingMode
+ * @param mode string representation of the TimingMode
+ * @return TimingMode
+ * @throw runtime_error if the string does not match any TimingMode
+ */
+template <> TimingMode string_to(const std::string &arg);
+
+/**
+ * @brief Convert a string to FrameDiscardPolicy
+ * @param mode string representation of the FrameDiscardPolicy
+ * @return FrameDiscardPolicy
+ * @throw runtime_error if the string does not match any FrameDiscardPolicy
+ */
+template <> FrameDiscardPolicy string_to(const std::string &arg);
+
+/**
+ * @brief Convert a string to a DACIndex
+ * @param arg string representation of the dacIndex
+ * @return DACIndex
+ * @throw invalid argument error if the string does not match any DACIndex
+ */
+template <> DACIndex string_to(const std::string &arg);
+
+
+
+
+
+
+
+} // namespace aare