CMakeLists.txt

@@ -210,6 +210,7 @@ set( fc_sources
      src/variant.cpp
      src/exception.cpp
      src/variant_object.cpp
+     src/static_variant.cpp
      src/thread/thread.cpp
      src/thread/thread_specific.cpp
      src/thread/future.cpp

include/fc/static_variant.hpp

@@ -1,4 +1,4 @@
-/** This source adapted from https://github.com/kmicklas/variadic-static_variant
+/** This source adapted from https://github.com/kmicklas/variadic-static_variant. Now available at https://github.com/kmicklas/variadic-variant.
  *
  * Copyright (C) 2013 Kenneth Micklas
  *
@@ -176,6 +176,41 @@ struct type_info<> {
     static const size_t size = 0;
 };
 
+template<typename TTag>
+size_t size( TTag )
+{
+    return 0;
+}
+
+template<typename TTag, typename A, typename...Ts>
+size_t size( TTag tag )
+{
+    if (tag <= 0)
+    {
+        return sizeof(A);
+    }
+
+    return size<TTag, Ts...>( --tag );
+}
+
+
+class dynamic_storage
+{
+    char* storage;
+public:
+    dynamic_storage();
+
+    ~dynamic_storage();
+
+    void* data() const;
+
+    void alloc( size_t size );
+
+    void release();
+};
+
+
+
 } // namespace impl
 
 template<typename Visitor,typename Data>
@@ -213,40 +248,57 @@ class static_variant {
     static_assert(impl::type_info<Types...>::no_reference_types, "Reference types are not permitted in static_variant.");
     static_assert(impl::type_info<Types...>::no_duplicates, "static_variant type arguments contain duplicate types.");
 
+    template<typename X>
+    using type_in_typelist = typename std::enable_if<impl::position<X, Types...>::pos != -1, X>::type; // type is in typelist of static_variant.
+
     using tag_type = int64_t;
     tag_type _tag;
-    char storage[impl::type_info<Types...>::size];
+    impl::dynamic_storage storage;
 
-    template<typename X>
+    template<typename X, typename = type_in_typelist<X>>
     void init(const X& x) {
         _tag = impl::position<X, Types...>::pos;
-        new(storage) X(x);
+        storage.alloc( sizeof(X) );
+        new(storage.data()) X(x);
     }
 
-    template<typename X>
+    template<typename X, typename = type_in_typelist<X>>
     void init(X&& x) {
         _tag = impl::position<X, Types...>::pos;
-        new(storage) X( std::move(x) );
+        storage.alloc( sizeof(X) );
+        new(storage.data()) X( std::move(x) );
     }
 
+    void init(tag_type tag)
+    {
+        FC_ASSERT( tag >= 0 );
+        FC_ASSERT( tag < count() );
+        _tag = tag;
+        storage.alloc( impl::size<tag_type, Types...>( tag ) );
+        impl::storage_ops<0, Types...>::con(_tag, storage.data());
+    }
+
+    void clean()
+    {
+        impl::storage_ops<0, Types...>::del(_tag, storage.data() );
+        storage.release();
+    }
+
+
     template<typename StaticVariant>
     friend struct impl::copy_construct;
     template<typename StaticVariant>
     friend struct impl::move_construct;
 public:
-    template<typename X>
+    template<typename X, typename = type_in_typelist<X>>
     struct tag
     {
-       static_assert(
-         impl::position<X, Types...>::pos != -1,
-         "Type not in static_variant."
-       );
        static const int value = impl::position<X, Types...>::pos;
     };
+
     static_variant()
     {
-       _tag = 0;
+        init(0);
-       impl::storage_ops<0, Types...>::con(0, storage);
     }
 
     template<typename... Other>
@@ -254,6 +306,7 @@ public:
     {
        cpy.visit( impl::copy_construct<static_variant>(*this) );
     }
+
     static_variant( const static_variant& cpy )
     {
        cpy.visit( impl::copy_construct<static_variant>(*this) );
@@ -264,40 +317,32 @@ public:
        mv.visit( impl::move_construct<static_variant>(*this) );
     }
 
-    template<typename X>
+    template<typename X, typename = type_in_typelist<X>>
     static_variant(const X& v) {
-        static_assert(
-            impl::position<X, Types...>::pos != -1,
-            "Type not in static_variant."
-        );
         init(v);
     }
+
     ~static_variant() {
-       impl::storage_ops<0, Types...>::del(_tag, storage);
+       clean();
     }
 
-
+    template<typename X, typename = type_in_typelist<X>>
-    template<typename X>
     static_variant& operator=(const X& v) {
-        static_assert(
+        clean();
-            impl::position<X, Types...>::pos != -1,
-            "Type not in static_variant."
-        );
-        this->~static_variant();
         init(v);
         return *this;
     }
     static_variant& operator=( const static_variant& v )
     {
        if( this == &v ) return *this;
-       this->~static_variant();
+       clean();
        v.visit( impl::copy_construct<static_variant>(*this) );
        return *this;
     }
     static_variant& operator=( static_variant&& v )
     {
        if( this == &v ) return *this;
-       this->~static_variant();
+       clean();
        v.visit( impl::move_construct<static_variant>(*this) );
        return *this;
     }
@@ -310,52 +355,40 @@ public:
        return a.which() < b.which();
     }
 
-    template<typename X>
+    template<typename X, typename = type_in_typelist<X>>
     X& get() {
-        static_assert(
-            impl::position<X, Types...>::pos != -1,
-            "Type not in static_variant."
-        );
         if(_tag == impl::position<X, Types...>::pos) {
-            void* tmp(storage);
+            return *reinterpret_cast<X*>(storage.data());
-            return *reinterpret_cast<X*>(tmp);
         } else {
             FC_THROW_EXCEPTION( fc::assert_exception, "static_variant does not contain a value of type ${t}", ("t",fc::get_typename<X>::name()) );
-           //     std::string("static_variant does not contain value of type ") + typeid(X).name()
-           // );
         }
     }
-    template<typename X>
+    template<typename X, typename = type_in_typelist<X>>
     const X& get() const {
-        static_assert(
-            impl::position<X, Types...>::pos != -1,
-            "Type not in static_variant."
-        );
         if(_tag == impl::position<X, Types...>::pos) {
-            const void* tmp(storage);
+            return *reinterpret_cast<const X*>(storage.data());
-            return *reinterpret_cast<const X*>(tmp);
         } else {
             FC_THROW_EXCEPTION( fc::assert_exception, "static_variant does not contain a value of type ${t}", ("t",fc::get_typename<X>::name()) );
         }
     }
     template<typename visitor>
     typename visitor::result_type visit(visitor& v) {
-        return visit( _tag, v, (void*) storage );
+        return visit( _tag, v, (void*) storage.data() );
     }
 
     template<typename visitor>
     typename visitor::result_type visit(const visitor& v) {
-        return visit( _tag, v, (void*) storage );
+        return visit( _tag, v, (void*) storage.data() );
     }
 
     template<typename visitor>
     typename visitor::result_type visit(visitor& v)const {
-        return visit( _tag, v, (const void*) storage );
+        return visit( _tag, v, (const void*) storage.data() );
     }
 
     template<typename visitor>
     typename visitor::result_type visit(const visitor& v)const {
-        return visit( _tag, v, (const void*) storage );
+        return visit( _tag, v, (const void*) storage.data() );
     }
 
     template<typename visitor>
@@ -394,9 +427,8 @@ public:
     void set_which( tag_type w ) {
       FC_ASSERT( w >= 0 );
       FC_ASSERT( w < count() );
-      this->~static_variant();
+      clean();
-      _tag = w;
+      init(w);
-      impl::storage_ops<0, Types...>::con(_tag, storage);
     }
 
     tag_type which() const {return _tag;}

src/static_variant.cpp

@@ -0,0 +1,31 @@
+#include <fc/static_variant.hpp>
+
+
+namespace fc { namespace impl {
+
+dynamic_storage::dynamic_storage() : storage(nullptr) {};
+
+dynamic_storage::~dynamic_storage()
+{
+    release();
+}
+
+void* dynamic_storage::data() const
+{
+    assert( storage != nullptr );
+    return (void*)storage;
+}
+
+void dynamic_storage::alloc( size_t size )
+{
+    release();
+    storage = new char[size];
+}
+
+void dynamic_storage::release()
+{
+    delete [] storage;
+    storage = nullptr;
+}
+
+}}