A better return_type_tinfo() mechanism.

[ginac.git] / ginac / registrar.h

diff --git a/ginac/registrar.h b/ginac/registrar.h
index d1f4a5c9d1b3e70a03cb771332fad7982c78eb48..d8a64db241dff5d99b720ec501eb7782602ee1fe 100644 (file)
--- a/ginac/registrar.h
+++ b/ginac/registrar.h
@@ -38,6 +38,43 @@ class archive_node;
 template <template <class T, class = std::allocator<T> > class> class container;
 typedef container<std::list> lst;
 
+/** To distinguish between different kinds of non-commutative objects */
+struct return_type_t
+{
+       /// to distinguish between non-commutative objects of different type.
+       std::type_info const* tinfo; 
+       /// to distinguish between non-commutative objects of the same type.
+       /// Think of gamma matrices with different represenation labels.
+       unsigned rl;
+
+       /// Strict weak ordering (so one can put return_type_t's into
+       /// a STL container).
+       inline bool operator<(const return_type_t& other) const
+       {
+               if (tinfo->before(*other.tinfo))
+                       return true;
+               return rl < other.rl;
+       }
+       inline bool operator==(const return_type_t& other) const
+       {
+               if (*tinfo != *(other.tinfo))
+                       return false;
+               return rl == other.rl;
+       }
+       inline bool operator!=(const return_type_t& other) const
+       {
+               return ! (operator==(other));
+       }
+};
+
+template<typename T> inline return_type_t make_return_type_t(const unsigned rl = 0)
+{
+       return_type_t ret;
+       ret.rl = rl;
+       ret.tinfo = &typeid(T);
+       return ret;
+}
+
 /** Definitions for the tinfo mechanism. */
 typedef const void * tinfo_t;
 struct tinfo_static_t {};