Add more flexible versions of the load function

Firstly there's a variadic version of the basic load function.  Secondly
and perhaps more importantly there are versions which can load an object
from a file stored in a collection.  All of these are only implemented
for C++11 for now, since supporting the old version seems increasingly
irrelevant.

diff --git a/source/loader.h b/source/loader.h
index fe928048508d208aafe339def238a4cdc722dc2d..207ecff8dff8d7f068aa033994ef2a5e608ba56a 100644 (file)
--- a/source/loader.h
+++ b/source/loader.h
@@ -4,6 +4,7 @@
 #include <map>
 #include <msp/io/file.h>
 #include "loaderaction.h"
+#include "meta.h"
 #include "parser.h"
 #include "statement.h"
 
@@ -149,6 +150,52 @@ protected:
 };
 
 
+#if __cplusplus>=201103L
+/**
+Loads an object from a file.  The object must have a public Loader class.  Any
+extra arguments are passed to the Loader constructor.
+*/
+template<typename T, typename... Args>
+void load(T &obj, const std::string &fn, Args &... args)
+{
+       IO::BufferedFile in(fn);
+
+       Parser parser(in, fn);
+       typename T::Loader loader(obj, args...);
+       loader.load(parser);
+}
+
+/**
+Loads an object from a file stored in a collection.  The object must havea
+public Loader class.  The collection is passed to the Loader constructor,
+followed by any extra arguments.
+*/
+template<typename T, typename... Args>
+void load(T &obj, typename T::Loader::Collection &coll, const std::string &fn, Args &... args)
+{
+       RefPtr<IO::Seekable> in = coll.open_raw(fn);
+
+       Parser parser(*in, fn);
+       typename T::Loader loader(obj, coll, args...);
+       loader.load(parser);
+}
+
+/**
+Loads an object from a file stored in a collection.  The object must havea
+public Loader class.  Any extra arguments are passed to the Loader constructor.
+*/
+template<typename T, typename C, typename... Args>
+typename EnableIf<NeedsCollection<typename T::Loader>::value, void>::No load(T &obj, C &coll, const std::string &fn, Args &... args)
+{
+       RefPtr<IO::Seekable> in = coll.open_raw(fn);
+
+       Parser parser(*in, fn);
+       typename T::Loader loader(obj, args...);
+       loader.load(parser);
+}
+
+#else
+
 /**
 Loads an object from a file.  The object must have a public Loader class.
 */
@@ -162,6 +209,10 @@ void load(T &obj, const std::string &fn)
        loader.load(parser);
 }
 
+/**
+Loads an object from a file, passing one extra argument to the Loader
+constructor.  The object must have a public Loader class.
+*/
 template<typename T, typename U>
 void load(T &obj, const std::string &fn, U &arg)
 {
@@ -171,6 +222,7 @@ void load(T &obj, const std::string &fn, U &arg)
        typename T::Loader loader(obj, arg);
        loader.load(parser);
 }
+#endif
 
 } // namespace DataFile
 } // namespace Msp