X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Fcore%2Fmaputils.h;h=0f863b46fdf7dea307f251be4823a4e63cdcbc4e;hb=b2333b53a0434eb6a131000c0b9bf06e4f603bd6;hp=9548714658d806fad41614357bc0e60fa8444cdf;hpb=933356a36607f5d4480172e285071d4d7dfc5a7b;p=libs%2Fcore.git

diff --git a/source/core/maputils.h b/source/core/maputils.h
index 9548714..0f863b4 100644
--- a/source/core/maputils.h
+++ b/source/core/maputils.h
@@ -3,14 +3,54 @@
 
 #include <stdexcept>
 #include <typeinfo>
+#include <msp/strings/lexicalcast.h>
 
 namespace Msp {
 
+namespace MapUtilsInternal {
+
+/* This dummy struct is used to introduce a conversion, making the overloaded
+operator below worse than the templated one provided in lexicalcast.h. */
+struct Any
+{
+	template<typename T>
+	Any(const T &) { }
+};
+
+/* This must be hidden in the internal namespace to avoid interfering with
+other things. */
+inline void operator<<(LexicalConverter &, Any)
+{ }
+
+template<typename T>
+static std::string stringify_key(const T &k)
+{
+	try
+	{
+		LexicalConverter conv((Fmt()));
+		conv<<k;
+		return conv.get();
+	}
+	catch(const lexical_error &)
+	{
+		return "<cannot display value>";
+	}
+}
+
+} // namespace Internal
+
 class key_error: public std::runtime_error
 {
 public:
-	key_error(const std::type_info &);
-	~key_error() throw() { }
+	template<typename T>
+	key_error(const T &k):
+		runtime_error(make_what(typeid(T), MapUtilsInternal::stringify_key(k)))
+	{ }
+
+	virtual ~key_error() throw() { }
+
+private:
+	static std::string make_what(const std::type_info &, const std::string &);
 };
 
 
@@ -19,7 +59,7 @@ 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));
+		throw key_error(key);
 
 	return i->second;
 }
@@ -29,7 +69,7 @@ const typename T::mapped_type &get_item(const T &map, const typename T::key_type
 {
 	typename T::const_iterator i = map.find(key);
 	if(i==map.end())
-		throw key_error(typeid(T));
+		throw key_error(key);
 
 	return i->second;
 }
@@ -38,7 +78,7 @@ template<typename T>
 const typename T::iterator insert_unique(T &map, const typename T::key_type &key, const typename T::mapped_type &item)
 {
 	if(map.count(key))
-		throw key_error(typeid(T));
+		throw key_error(key);
 
 	return map.insert(typename T::value_type(key, item)).first;
 }