From 44b0a487f90b61e69238ead0aa0816498a95097d Mon Sep 17 00:00:00 2001
From: Joseph Schuchart <joseph.schuchart@stonybrook.edu>
Date: Tue, 29 Oct 2024 15:30:42 -0400
Subject: [PATCH] Move around type traits for buffer, scratch, and ptr

Signed-off-by: Joseph Schuchart <joseph.schuchart@stonybrook.edu>
---
 ttg/ttg/buffer.h        | 20 ++++++++++++++++++++
 ttg/ttg/device/task.h   |  5 +++--
 ttg/ttg/devicescratch.h | 19 +++++++++++++++++++
 ttg/ttg/parsec/buffer.h |  3 +--
 ttg/ttg/ptr.h           | 12 ++++++++++++
 ttg/ttg/util/meta.h     | 24 ++++--------------------
 6 files changed, 59 insertions(+), 24 deletions(-)

diff --git a/ttg/ttg/buffer.h b/ttg/ttg/buffer.h
index 3de6bcecd..59a926415 100644
--- a/ttg/ttg/buffer.h
+++ b/ttg/ttg/buffer.h
@@ -4,12 +4,32 @@
 #include <memory>
 
 #include "ttg/fwd.h"
+#include "ttg/util/meta.h"
 
 namespace ttg {
 
 template<typename T, typename Allocator = std::allocator<std::decay_t<T>>>
 using Buffer = TTG_IMPL_NS::Buffer<T, Allocator>;
 
+namespace meta {
+
+  /* Specialize some traits */
+
+  template<typename T, typename A>
+  struct is_buffer<ttg::Buffer<T, A>> : std::true_type
+  { };
+
+  template<typename T, typename A>
+  struct is_buffer<const ttg::Buffer<T, A>> : std::true_type
+  { };
+
+  /* buffers are const if their value types are const */
+  template<typename T, typename A>
+  struct is_const<ttg::Buffer<T, A>> : std::is_const<T>
+  { };
+
+} // namespace meta
+
 } // namespace ttg
 
 #endif // TTG_buffer_H
\ No newline at end of file
diff --git a/ttg/ttg/device/task.h b/ttg/ttg/device/task.h
index 09ab93750..e6fe365a1 100644
--- a/ttg/ttg/device/task.h
+++ b/ttg/ttg/device/task.h
@@ -33,11 +33,12 @@ namespace ttg::device {
     /* extract buffer information from to_device_t */
     template<typename... Ts, std::size_t... Is>
     auto extract_buffer_data(detail::to_device_t<Ts...>& a, std::index_sequence<Is...>) {
+      using arg_types = std::tuple<Ts...>;
       return std::array{
                 device_input_data_t{TTG_IMPL_NS::buffer_data(std::get<Is>(a.ties)),
                                     std::get<Is>(a.ties).scope(),
-                                    std::is_const_v<std::tuple_element<Is, decltype(a.ties)>>,
-                                    ttg::meta::is_devicescratch_v<std::tuple_element<Is, decltype(a.ties)>>}...};
+                                    ttg::meta::is_const_v<std::tuple_element<Is, arg_types>>,
+                                    ttg::meta::is_devicescratch_v<std::tuple_element<Is, arg_types>>}...};
     }
   }  // namespace detail
 
diff --git a/ttg/ttg/devicescratch.h b/ttg/ttg/devicescratch.h
index 9ccb60bce..e4ed692c9 100644
--- a/ttg/ttg/devicescratch.h
+++ b/ttg/ttg/devicescratch.h
@@ -3,6 +3,7 @@
 
 #include "ttg/devicescope.h"
 #include "ttg/fwd.h"
+#include "ttg/util/meta.h"
 
 namespace ttg {
 
@@ -14,6 +15,24 @@ auto make_scratch(T* val, ttg::scope scope, std::size_t count = 1) {
   return devicescratch<T>(val, scope, count);
 }
 
+namespace meta {
+
+  /* Specialize some traits */
+
+  template<typename T>
+  struct is_devicescratch<ttg::devicescratch<T>> : std::true_type
+  { };
+
+  template<typename T>
+  struct is_devicescratch<const ttg::devicescratch<T>> : std::true_type
+  { };
+
+  template<typename T>
+  struct is_const<ttg::devicescratch<T>> : std::is_const<T>
+  { };
+
+} // namespace meta
+
 } // namespace ttg
 
 #endif // TTG_DEVICESCRATCH_H
\ No newline at end of file
diff --git a/ttg/ttg/parsec/buffer.h b/ttg/ttg/parsec/buffer.h
index ba0c2a096..075493078 100644
--- a/ttg/ttg/parsec/buffer.h
+++ b/ttg/ttg/parsec/buffer.h
@@ -11,6 +11,7 @@
 #include "ttg/util/iovec.h"
 #include "ttg/device/device.h"
 #include "ttg/parsec/device.h"
+#include "ttg/devicescope.h"
 
 #if defined(PARSEC_HAVE_DEV_CUDA_SUPPORT)
 #include <cuda_runtime.h>
@@ -457,8 +458,6 @@ struct Buffer : public detail::ttg_parsec_data_wrapper_t
     }
   }
 #endif // TTG_SERIALIZATION_SUPPORTS_MADNESS
-
-
 };
 
 namespace detail {
diff --git a/ttg/ttg/ptr.h b/ttg/ttg/ptr.h
index c6c92006f..f817a5498 100644
--- a/ttg/ttg/ptr.h
+++ b/ttg/ttg/ptr.h
@@ -3,6 +3,8 @@
 
 #include "ttg/fwd.h"
 
+#include "ttg/util/meta.h"
+
 namespace ttg {
 
 template<typename T>
@@ -18,6 +20,16 @@ inline Ptr<std::decay_t<T>> get_ptr(T&& obj) {
   return TTG_IMPL_NS::get_ptr(std::forward<T>(obj));
 }
 
+namespace meta {
+
+  /* specialize some traits */
+
+  template<typename T>
+  struct is_ptr<ttg::Ptr<T>> : std::true_type
+  { };
+
+} // namespace ptr
+
 #if 0
 namespace detail {
 
diff --git a/ttg/ttg/util/meta.h b/ttg/ttg/util/meta.h
index f3af03152..a7334ce56 100644
--- a/ttg/ttg/util/meta.h
+++ b/ttg/ttg/util/meta.h
@@ -6,9 +6,6 @@
 
 #include "ttg/util/span.h"
 #include "ttg/util/typelist.h"
-#include "ttg/buffer.h"
-#include "ttg/ptr.h"
-#include "ttg/devicescratch.h"
 
 namespace ttg {
 
@@ -302,25 +299,14 @@ namespace ttg {
     struct is_ptr : std::false_type
     { };
 
-    template<typename T>
-    struct is_ptr<ttg::Ptr<T>> : std::true_type
-    { };
-
     template<typename T>
     constexpr bool is_ptr_v = is_ptr<T>::value;
 
+    /* specialized by the implementation */
     template<typename T>
     struct is_buffer : std::false_type
     { };
 
-    template<typename T, typename A>
-    struct is_buffer<ttg::Buffer<T, A>> : std::true_type
-    { };
-
-    template<typename T, typename A>
-    struct is_buffer<const ttg::Buffer<T, A>> : std::true_type
-    { };
-
     template<typename T>
     constexpr bool is_buffer_v = is_buffer<T>::value;
 
@@ -329,16 +315,14 @@ namespace ttg {
     { };
 
     template<typename T>
-    struct is_devicescratch<ttg::devicescratch<T>> : std::true_type
-    { };
+    constexpr bool is_devicescratch_v = is_devicescratch<T>::value;
 
     template<typename T>
-    struct is_devicescratch<const ttg::devicescratch<T>> : std::true_type
+    struct is_const : std::is_const<T>
     { };
 
     template<typename T>
-    constexpr bool is_devicescratch_v = is_devicescratch<T>::value;
-
+    constexpr bool is_const_v = is_const<T>::value;
 
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
     // typelist metafunctions