From bd7105ff8683a680d1270eca8cd74f9002144dbd Mon Sep 17 00:00:00 2001
From: Tim Foley <tfoley@nvidia.com>
Date: Mon, 10 Jul 2017 15:40:42 -0700
Subject: Initial work on handling resources in structs during
 cross-compilation

- The basic idea is that during the "lowering" pass, some types (notably: aggregate types that contain resource variables) will get turned into "tuple" types, which are pseduo-types that aren't meant to survive lowering.

- An attempt to declare a variable with a tuple type expands into a tuple of declarations

- An attempt to reference such a tuple-ified variable leads to a tuple of expressions

- An attempt to extract a member from such a tuple expression will pick the appropriate sub-element

- Dereference a tuple by dereferencing the primary expression

- Expand a tuple in the argument list to a call into N arguments (by recursively flattening the tuple)

- Don't create tuple types when not generating GLSL

- Make sure to preserve the specialized type of a call expression through lowering, since emission of unchecked calls relies on that info.
  - TODO: maybe the infix/prefix/postifx/select information should come in as a side-band? Should we have modifiers on expressions?

- Make sure to offset the layout for a nested field based on teh base offset of its parent variable, when generating declarations for nested fields
---
 source/slang/syntax.h | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

(limited to 'source/slang/syntax.h')

diff --git a/source/slang/syntax.h b/source/slang/syntax.h
index de5467c71..83b2f5801 100644
--- a/source/slang/syntax.h
+++ b/source/slang/syntax.h
@@ -231,6 +231,65 @@ namespace Slang
         RefPtr<ExpressionType> operator->() { return type; }
     };
 
+    // A reference to a class of syntax node, that can be
+    // used to create instances on the fly
+    struct SyntaxClassBase
+    {
+        typedef void* (*CreateFunc)();
+
+        SyntaxClassBase()
+        {}
+
+        SyntaxClassBase(CreateFunc createFunc)
+            : createFunc(createFunc)
+        {}
+
+        void* createInstanceImpl()
+        {
+            return createFunc ? createFunc() : nullptr;
+        }
+
+        CreateFunc createFunc = nullptr;
+
+        template<typename T>
+        struct Impl
+        {
+            static void* createFunc();
+        };
+    };
+
+    template<typename T>
+    struct SyntaxClass : SyntaxClassBase
+    {
+        SyntaxClass()
+        {}
+
+        template <typename U>
+        SyntaxClass(SyntaxClass<U> const& other,
+            typename EnableIf<IsConvertible<T*, U*>::Value, void>::type* = 0)
+            : SyntaxClassBase(other.createFunc)
+        {
+        }
+
+        T* createInstance()
+        {
+            return (T*)createInstanceImpl();
+        }
+
+        static SyntaxClass<T> getClass()
+        {
+            SyntaxClass<T> result;
+            result.createFunc = &SyntaxClass::Impl<T>::createFunc;
+            return result;
+        }
+    };
+
+    template<typename T>
+    SyntaxClass<T> getClass()
+    {
+        return SyntaxClass<T>::getClass();
+    }
+
 
     // A reference to a declaration, which may include
     // substitutions for generic parameters.
-- 
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