Add structure chain constructor which accepts a list of its elements (#217)

Add structure chain constructor which accepts a list of its elements

README.md

@@ -182,6 +182,15 @@ vk::MemoryAllocateInfo &allocInfo = c.get<vk::MemoryAllocateInfo>();
 vk::ImportMemoryFdInfoKHR &fdInfo = c.get<vk::ImportMemoryFdInfoKHR>();
 ```
 
+Vulkan-Hpp provides a constructor for these chains similar to the CreateInfo objects which accepts a list of all structures part of the chain. The `pNext` field is automatically set to the correct value:
+
+```c++
+vk::StructureChain<vk::MemoryAllocateInfo, vk::MemoryDedicatedAllocateInfo> c = {
+  vk::MemoryAllocateInfo(size, type),
+  vk::MemoryDedicatedAllocateInfo(image)
+};
+```
+
 Sometimes the user has to pass a preallocated structure chain to query information. In those cases the corresponding query functions are variadic templates and do accept a structure chain to construct the return value:
 
 ```

VulkanHppGenerator.cpp

@@ -398,6 +398,11 @@ const std::string structureChainHeader = R"(
       linkAndCopy<StructureElements...>(rhs);
     }
 
+    StructureChain(StructureElements const &... elems)
+    {
+      linkAndCopyElements<StructureElements...>(elems...);
+    }
+
     StructureChain& operator=(StructureChain const &rhs)
     {
       linkAndCopy<StructureElements...>(rhs);
@@ -439,7 +444,24 @@ const std::string structureChainHeader = R"(
       linkAndCopy<Y, Z...>(rhs);
     }
 
-};
+    template<typename X>
+    void linkAndCopyElements(X const &xelem)
+    {
+      static_cast<X&>(*this) = xelem;
+    }
+
+    template<typename X, typename Y, typename ...Z>
+    void linkAndCopyElements(X const &xelem, Y const &yelem, Z const &... zelem)
+    {
+      static_assert(isStructureChainValid<X,Y>::value, "The structure chain is not valid!");
+      X& x = static_cast<X&>(*this);
+      Y& y = static_cast<Y&>(*this);
+      x = xelem;
+      x.pNext = &y;
+      linkAndCopyElements<Y, Z...>(yelem, zelem...);
+    }
+  };
+
 )";
 
 const std::string versionCheckHeader = R"(

vulkan/vulkan.hpp

@@ -471,6 +471,11 @@ namespace VULKAN_HPP_NAMESPACE
       linkAndCopy<StructureElements...>(rhs);
     }
 
+    StructureChain(StructureElements const &... elems)
+    {
+      linkAndCopyElements<StructureElements...>(elems...);
+    }
+
     StructureChain& operator=(StructureChain const &rhs)
     {
       linkAndCopy<StructureElements...>(rhs);
@@ -512,7 +517,24 @@ namespace VULKAN_HPP_NAMESPACE
       linkAndCopy<Y, Z...>(rhs);
     }
 
-};
+    template<typename X>
+    void linkAndCopyElements(X const &xelem)
+    {
+      static_cast<X&>(*this) = xelem;
+    }
+
+    template<typename X, typename Y, typename ...Z>
+    void linkAndCopyElements(X const &xelem, Y const &yelem, Z const &... zelem)
+    {
+      static_assert(isStructureChainValid<X,Y>::value, "The structure chain is not valid!");
+      X& x = static_cast<X&>(*this);
+      Y& y = static_cast<Y&>(*this);
+      x = xelem;
+      x.pNext = &y;
+      linkAndCopyElements<Y, Z...>(yelem, zelem...);
+    }
+  };
+
   enum class Result
   {
     eSuccess = VK_SUCCESS,