except: split try_array into try_values/try_handles

sometimes we will need to coerce types from try_array into our own
wrapper types and it is a little difficult to express the required types
in the one template function.

except.hpp

@@ -101,7 +101,38 @@ namespace cruft::vk {
             typename ...Args
         >
         static auto
-        try_array (FuncT &&func, Args &&...args)
+        try_values (FuncT &&func, Args &&...args)
+        {
+            // extract the number of elements available
+            uint32_t expected = 0;
+            try_func (func, args..., &expected, nullptr);
+
+            // find the type of the last argument, ie. the values we're
+            // requesting
+            using ValueT = std::remove_pointer_t<
+                std::tuple_element_t<
+                    sizeof...(Args) + 1,
+                    typename func_traits<FuncT>::argument_types
+                >
+            >;
+
+            ContainerT<ValueT> values (expected);
+            uint32_t found = expected;
+            try_func (func, args..., &found, values.data ());
+            CHECK_EQ (expected, found);
+            return values;
+        }
+
+
+        //---------------------------------------------------------------------
+        template <
+            typename ReturnT,
+            template <typename,typename...> class ContainerT = std::vector,
+            typename FuncT,
+            typename ...Args
+        >
+        static auto
+        try_handles (FuncT &&func, Args &&...args)
         {
             // extract the number of elements available
             uint32_t expected = 0;
@@ -118,18 +149,15 @@ namespace cruft::vk {
 
             // return the values on the stack temporarily as we may need to
             // convert them to a seperate result type.
-            //
-            // TODO: remove this intermediate step where we don't actually
-            // have a conversion to do, ie ResultT == ValueT.
             ValueT values[expected];
             uint32_t found = expected;
             try_func (func, args..., &found, &values[0]);
             CHECK_EQ (expected, found);
 
             // convert to the requested type
-            return ContainerT<ValueT> {
-                &values[0],
-                &values[found]
+            return ContainerT<ReturnT> {
+                values + 0,
+                values + found,
             };
         }
     };
@@ -161,4 +189,5 @@ namespace cruft::vk {
     };
 }
 
+
 #endif

physical_device.cpp

@@ -84,7 +84,7 @@ physical_device::memory_properties (void) const
 std::vector<VkQueueFamilyProperties>
 physical_device::queue_families (void) const
 {
-    return error::try_array (
+    return error::try_values (
         vkGetPhysicalDeviceQueueFamilyProperties, native ()
     );
 }
@@ -94,7 +94,7 @@ physical_device::queue_families (void) const
 std::vector<VkSurfaceFormatKHR>
 physical_device::surface_formats (surface &_surface)
 {
-    return error::try_array (
+    return error::try_values (
         vkGetPhysicalDeviceSurfaceFormatsKHR,
         native (), _surface.native ()
     );
@@ -105,7 +105,7 @@ physical_device::surface_formats (surface &_surface)
 std::vector<VkPresentModeKHR>
 physical_device::present_modes (surface &_surface)
 {
-    return error::try_array (
+    return error::try_values (
         vkGetPhysicalDeviceSurfacePresentModesKHR,
         native (), _surface.native ()
     );

tools/hello.cpp

@@ -254,7 +254,7 @@ main (void)
     cruft::vk::error::try_code (
         vkGetSwapchainImagesKHR (ldevice.native (), swapchain, &swap_image_count, nullptr)
     );
-    std::vector<VkImage> swap_images = cruft::vk::error::try_array (
+    std::vector<VkImage> swap_images = cruft::vk::error::try_values (
         vkGetSwapchainImagesKHR, ldevice.native (), swapchain
     );