[BL] Add ConfigTree::getConfParam* for vector<T>.

BaseLib/ConfigTree-impl.h

@@ -9,6 +9,8 @@
 
 #include "ConfigTree.h"
 
+#include <sstream>
+
 namespace BaseLib
 {
 
@@ -50,15 +52,37 @@ getConfParam(std::string const& param, T const& default_value) const
     return default_value;
 }
 
-template<typename T>
-boost::optional<T>
-ConfigTree::
-getConfParamOptional(std::string const& param) const
+template <typename T>
+boost::optional<T> ConfigTree::getConfParamOptional(
+    std::string const& param) const
 {
     checkUnique(param);
 
+    return getConfParamOptionalImpl(param, static_cast<T*>(nullptr));
+}
+
+template <typename T>
+boost::optional<T> ConfigTree::getConfParamOptionalImpl(
+    std::string const& param, T*) const
+{
+    if (auto p = getConfSubtreeOptional(param)) return p->getValue<T>();
+
+    return boost::none;
+}
+
+template <typename T>
+boost::optional<std::vector<T>> ConfigTree::getConfParamOptionalImpl(
+    std::string const& param, std::vector<T>*) const
+{
     if (auto p = getConfSubtreeOptional(param))
-        return p->getValue<T>();
+    {
+        std::istringstream sstr{p->getValue<std::string>()};
+        std::vector<T> result;
+        T value;
+        while (sstr >> value)
+            result.push_back(value);
+        return boost::make_optional(result);
+    }
 
     return boost::none;
 }

BaseLib/ConfigTree.h

@@ -15,6 +15,7 @@
 
 #include <functional>
 #include <memory>
+#include <vector>
 
 #include <boost/property_tree/ptree.hpp>
 
@@ -497,6 +498,15 @@ public:
     static void onwarning(std::string const& filename, std::string const& path,
                           std::string const& message);
 
+private:
+    //! Default implementation of reading a value of type T.
+    template<typename T> boost::optional<T>
+    getConfParamOptionalImpl(std::string const& param, T*) const;
+
+    //! Implementation of reading a vector of values of type T.
+    template<typename T> boost::optional<std::vector<T>>
+    getConfParamOptionalImpl(std::string const& param, std::vector<T>*) const;
+
 private:
     struct CountType
     {