documentation updates inspired by ACCU Overload

include/safe_base.hpp

@@ -253,15 +253,17 @@ public:
         --(*this);
         return old_t;
     }
-    safe_base operator-(){ // unary minus
-        return *this = 0 - *this; // this will check for overflow
+    // return a safe type. This guarantees that result will
+    // be checked upon return
+    constexpr safe_base operator-() const { // unary minus
+        return 0 - *this; // this will check for overflow
     }
-    safe_base operator~(){
+    constexpr safe_base operator~() const {
         static_assert(
             std::numeric_limits<Stored>::is_signed,
             "Bitwise inversion of signed value is an error"
         );
-        return *this = ~(m_t);
+        return ~(m_t);
     }
 };
 

include/safe_base_operations.hpp

@@ -183,12 +183,6 @@ struct common_policies {
         "if the promotion policies are different, one must be void!"
     );
 
-    static_assert(
-        ! std::is_same<t_promotion_policy, void>::value
-        || !std::is_same<void, u_promotion_policy>::value,
-        "at least one promotion polcy must be non void"
-    );
-
     static_assert(
         ! (std::is_same<t_promotion_policy, void>::value
         && std::is_same<void, u_promotion_policy>::value),

include/safe_literal.hpp

@@ -13,6 +13,8 @@
 // http://www.boost.org/LICENSE_1_0.txt)
 
 #include <cstdint> // for intmax_t/uintmax_t
+#include <boost/mpl/if.hpp>
+
 #include "utility.hpp"
 #include "safe_base.hpp"
 #include "safe_base_operations.hpp"
@@ -94,6 +96,18 @@ public:
     constexpr operator R () const {
         return N;
     }
+    // return a safe type. This guarantees that result will
+    // be checked upon return
+    constexpr safe_literal_impl<decltype(-N), -N, P, E> operator-() const { // unary minus
+        return 0 - N; // this will check for overflow
+    }
+    constexpr safe_literal_impl<decltype(~N), -N, P, E> operator~() const {
+        static_assert(
+            std::numeric_limits<T>::is_signed,
+            "Bitwise inversion of signed value is an error"
+        );
+        return ~N;
+    }
 };
 
 template<
@@ -108,7 +122,7 @@ using safe_signed_literal = safe_literal_impl<
     E
 >;
 
-template <
+template<
     std::uintmax_t N,
     class P = native,
     class E = throw_exception
@@ -120,6 +134,13 @@ using safe_unsigned_literal = safe_literal_impl<
     E
 >;
 
+#define safe_literal(n)                               \
+    boost::mpl::if_c<                                 \
+        std::numeric_limits<decltype<n>>::is_signed>. \
+        safe_unsigned_literal<n, void, void>,               \
+        safe_signed_literal<n, void, void>                  \
+    >::type
+
 } // numeric
 } // boost