Add utility functions for getting an item from an std::map

diff --git a/source/core/maputils.cpp b/source/core/maputils.cpp
new file mode 100644 (file)
index 0000000..4fcc8e2
--- /dev/null
+++ b/source/core/maputils.cpp
@@ -0,0 +1,12 @@
+#include <msp/debug/demangle.h>
+#include "maputils.h"
+
+using namespace std;
+
+namespace Msp {
+
+key_error::key_error(const type_info &t):
+       runtime_error(Debug::demangle(t.name()))
+{ }
+
+} // namespace Msp

diff --git a/source/core/maputils.h b/source/core/maputils.h
new file mode 100644 (file)
index 0000000..1a7c0ae
--- /dev/null
+++ b/source/core/maputils.h
@@ -0,0 +1,38 @@
+#ifndef MSP_CORE_MAPUTILS_H_
+#define MSP_CORE_MAPUTILS_H_
+
+#include <stdexcept>
+#include <typeinfo>
+
+namespace Msp {
+
+class key_error: public std::runtime_error
+{
+public:
+       key_error(const std::type_info &);
+};
+
+
+template<typename T>
+typename T::mapped_type &get_item(T &map, const typename T::key_type &key)
+{
+       typename T::iterator i = map.find(key);
+       if(i==map.end())
+               throw key_error(typeid(T));
+
+       return i->second;
+}
+
+template<typename T>
+const typename T::mapped_type &get_item(const T &map, const typename T::key_type &key)
+{
+       typename T::const_iterator i = map.find(key);
+       if(i==map.end())
+               throw key_error(typeid(T));
+
+       return i->second;
+}
+
+} // namespace Msp
+
+#endif