Enable rebinding on AllocatorHandle and fix Blocked copy constructor issue (#89)

This PR introduces the ability to rebind `float` and `Float16` on
`AllocatorHandle`. Additionally, it addresses an issue where the
`Blocked` copy constructor failed to copy the allocator from another
instance.

Author: dian-lun-lin

include/svs/core/allocator.h

@@ -537,10 +537,15 @@ class AllocatorInterface {
 
     // covariant return type
     virtual AllocatorInterface* clone() const = 0;
+    virtual AllocatorInterface* rebind_float() const = 0;
+    virtual AllocatorInterface* rebind_float16() const = 0;
 };
 
 template <detail::Allocator Impl> class AllocatorImpl : public AllocatorInterface {
   public:
+    using rebind_allocator_float = lib::rebind_allocator_t<float, Impl>;
+    using rebind_allocator_float16 = lib::rebind_allocator_t<Float16, Impl>;
+
     // pass by value due to clone()
     explicit AllocatorImpl(Impl impl)
         : AllocatorInterface{}
@@ -554,6 +559,14 @@ template <detail::Allocator Impl> class AllocatorImpl : public AllocatorInterfac
 
     AllocatorImpl<Impl>* clone() const override { return new AllocatorImpl(impl_); }
 
+    AllocatorImpl<rebind_allocator_float>* rebind_float() const override {
+        return new AllocatorImpl<rebind_allocator_float>(rebind_allocator_float{impl_});
+    }
+
+    AllocatorImpl<rebind_allocator_float16>* rebind_float16() const override {
+        return new AllocatorImpl<rebind_allocator_float16>(rebind_allocator_float16{impl_});
+    }
+
   private:
     Impl impl_;
 };
@@ -580,6 +593,33 @@ template <typename T> class AllocatorHandle {
     AllocatorHandle& operator=(AllocatorHandle&&) = default;
     ~AllocatorHandle() = default;
 
+    // Enable rebinding of allocators.
+    template <typename U> friend class AllocatorHandle;
+
+    template <typename U>
+    AllocatorHandle(const AllocatorHandle<U>& other)
+        requires std::is_same_v<T, float> && (!std::is_same_v<U, T>)
+        : impl_{other.impl_->rebind_float()} {}
+    template <typename U>
+    AllocatorHandle(const AllocatorHandle<U>& other)
+        requires std::is_same_v<T, Float16> && (!std::is_same_v<U, T>)
+        : impl_{other.impl_->rebind_float16()} {}
+
+    template <typename U>
+    AllocatorHandle& operator=(const AllocatorHandle<U>& other)
+        requires std::is_same_v<T, float> && (!std::is_same_v<U, T>)
+    {
+        impl_.reset(other.impl_->rebind_float());
+        return *this;
+    }
+    template <typename U>
+    AllocatorHandle& operator=(const AllocatorHandle<U>& other)
+        requires std::is_same_v<T, Float16> && (!std::is_same_v<U, T>)
+    {
+        impl_.reset(other.impl_->rebind_float16());
+        return *this;
+    }
+
     T* allocate(size_t n) {
         if (impl_.get() == nullptr) {
             throw ANNEXCEPTION("Empty allocator handle!");

include/svs/core/data/simple.h

@@ -565,7 +565,8 @@ template <typename Alloc> class Blocked {
     template <typename U> friend class Blocked;
     template <typename U>
     Blocked(const Blocked<U>& other)
-        : parameters_{other.parameters_} {}
+        : parameters_{other.parameters_}
+        , allocator_{other.allocator_} {}
 
   private:
     BlockingParameters parameters_{};

tests/svs/core/allocator.cpp

@@ -196,5 +196,19 @@ CATCH_TEST_CASE("Testing Allocator", "[allocators]") {
 
             CATCH_STATIC_REQUIRE(std::is_same_v<decltype(ptr), svs::Float16*>);
         }
+        CATCH_SECTION("Rebind") {
+            auto alloc = svs::make_allocator_handle(svs::lib::Allocator<int>());
+            svs::lib::rebind_allocator_t<svs::Float16, decltype(alloc)> rebound_alloc{
+                alloc};
+            auto* ptr = rebound_alloc.allocate(num_elements);
+            rebound_alloc.deallocate(ptr, num_elements);
+            CATCH_STATIC_REQUIRE(std::is_same_v<decltype(ptr), svs::Float16*>);
+
+            svs::lib::rebind_allocator_t<float, decltype(alloc)> rebound_alloc2{
+                rebound_alloc};
+            auto* ptr2 = rebound_alloc2.allocate(num_elements);
+            rebound_alloc2.deallocate(ptr2, num_elements);
+            CATCH_STATIC_REQUIRE(std::is_same_v<decltype(ptr2), float*>);
+        }
     }
 }