Make StdAllocator C++17-20 compatible.

Author: ylavic

include/rapidjson/allocators.h

@@ -19,6 +19,11 @@
 
 #include <memory>
 
+#if RAPIDJSON_HAS_CXX11
+#include <limits>
+#include <type_traits>
+#endif
+
 RAPIDJSON_NAMESPACE_BEGIN
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -420,6 +425,11 @@ class StdAllocator :
     public std::allocator<T>
 {
     typedef std::allocator<T> allocator_type;
+#if RAPIDJSON_HAS_CXX11
+    typedef std::allocator_traits<allocator_type> traits_type;
+#else
+    typedef allocator_type traits_type;
+#endif
 
 public:
     typedef BaseAllocator BaseAllocatorType;
@@ -449,29 +459,50 @@ class StdAllocator :
     ~StdAllocator() RAPIDJSON_NOEXCEPT
     { }
 
-    typedef typename allocator_type::value_type       value_type;
-    typedef typename allocator_type::pointer          pointer;
-    typedef typename allocator_type::const_pointer    const_pointer;
-    typedef typename allocator_type::reference        reference;
-    typedef typename allocator_type::const_reference  const_reference;
-    typedef typename allocator_type::size_type        size_type;
-    typedef typename allocator_type::difference_type  difference_type;
-
     template<typename U>
     struct rebind {
         typedef StdAllocator<U, BaseAllocator> other;
     };
 
+    typedef typename traits_type::size_type         size_type;
+    typedef typename traits_type::difference_type   difference_type;
+    typedef typename traits_type::value_type        value_type;
+    typedef typename traits_type::pointer           pointer;
+    typedef typename traits_type::const_pointer     const_pointer;
+
 #if RAPIDJSON_HAS_CXX11
-    using allocator_type::max_size;
-    using allocator_type::address;
-    using allocator_type::construct;
-    using allocator_type::destroy;
-#else
+
+    typedef typename std::add_lvalue_reference<value_type>::type &reference;
+    typedef typename std::add_lvalue_reference<typename std::add_const<value_type>::type>::type &const_reference;
+
+    pointer address(reference r) const RAPIDJSON_NOEXCEPT
+    {
+        return std::addressof(r);
+    }
+    const_pointer address(const_reference r) const RAPIDJSON_NOEXCEPT
+    {
+        return std::addressof(r);
+    }
+
     size_t max_size() const RAPIDJSON_NOEXCEPT
     {
-        return allocator_type::max_size();
+        return std::numeric_limits<size_type>::max() / sizeof(value_type);
+    }
+
+    template <typename ...Args>
+    void construct(pointer p, Args &&...args)
+    {
+        ::new (static_cast<void*>(p)) value_type(std::forward<Args>(args)...);
     }
+    void destroy(pointer p)
+    {
+        p->~T();
+    }
+
+#else // !RAPIDJSON_HAS_CXX11
+
+    typedef typename allocator_type::reference       reference;
+    typedef typename allocator_type::const_reference const_reference;
 
     pointer address(reference r) const RAPIDJSON_NOEXCEPT
     {
@@ -482,6 +513,11 @@ class StdAllocator :
         return allocator_type::address(r);
     }
 
+    size_t max_size() const RAPIDJSON_NOEXCEPT
+    {
+        return allocator_type::max_size();
+    }
+
     void construct(pointer p, const_reference r)
     {
         allocator_type::construct(p, r);
@@ -490,7 +526,8 @@ class StdAllocator :
     {
         allocator_type::destroy(p);
     }
-#endif
+
+#endif // !RAPIDJSON_HAS_CXX11
 
     template <typename U>
     U* allocate(size_type n = 1, const void* = 0)

include/rapidjson/rapidjson.h

@@ -124,6 +124,17 @@
 #define RAPIDJSON_NAMESPACE_END }
 #endif
 
+///////////////////////////////////////////////////////////////////////////////
+// __cplusplus macro
+
+//!@cond RAPIDJSON_HIDDEN_FROM_DOXYGEN
+
+#if defined(_MSC_VER)
+#define RAPIDJSON_CPLUSPLUS _MSVC_LANG
+#else
+#define RAPIDJSON_CPLUSPLUS __cplusplus
+#endif
+
 ///////////////////////////////////////////////////////////////////////////////
 // RAPIDJSON_HAS_STDSTRING
 
@@ -411,7 +422,7 @@ RAPIDJSON_NAMESPACE_END
 
 // Prefer C++11 static_assert, if available
 #ifndef RAPIDJSON_STATIC_ASSERT
-#if __cplusplus >= 201103L || ( defined(_MSC_VER) && _MSC_VER >= 1800 )
+#if RAPIDJSON_CPLUSPLUS >= 201103L || ( defined(_MSC_VER) && _MSC_VER >= 1800 )
 #define RAPIDJSON_STATIC_ASSERT(x) \
    static_assert(x, RAPIDJSON_STRINGIFY(x))
 #endif // C++11
@@ -542,7 +553,7 @@ RAPIDJSON_NAMESPACE_END
 // C++11 features
 
 #ifndef RAPIDJSON_HAS_CXX11
-#define RAPIDJSON_HAS_CXX11 (__cplusplus >= 201103L)
+#define RAPIDJSON_HAS_CXX11 (RAPIDJSON_CPLUSPLUS >= 201103L)
 #endif
 
 #ifndef RAPIDJSON_HAS_CXX11_RVALUE_REFS
@@ -610,12 +621,16 @@ RAPIDJSON_NAMESPACE_END
 ///////////////////////////////////////////////////////////////////////////////
 // C++17 features
 
-#if defined(__has_cpp_attribute)
-# if __has_cpp_attribute(fallthrough)
-#  define RAPIDJSON_DELIBERATE_FALLTHROUGH [[fallthrough]]
-# else
-#  define RAPIDJSON_DELIBERATE_FALLTHROUGH
-# endif
+#ifndef RAPIDJSON_HAS_CXX17
+#define RAPIDJSON_HAS_CXX17 (RAPIDJSON_CPLUSPLUS >= 201703L)
+#endif
+
+#if RAPIDJSON_HAS_CXX17
+# define RAPIDJSON_DELIBERATE_FALLTHROUGH [[fallthrough]]
+#elif defined(__has_cpp_attribute) && __has_cpp_attribute(fallthrough)
+# define RAPIDJSON_DELIBERATE_FALLTHROUGH __attribute__((fallthrough))
+#elif defined(__has_cpp_attribute) && __has_cpp_attribute(clang::fallthrough)
+# define RAPIDJSON_DELIBERATE_FALLTHROUGH [[clang::fallthrough]]
 #else
 # define RAPIDJSON_DELIBERATE_FALLTHROUGH
 #endif

test/unittest/allocatorstest.cpp

@@ -107,20 +107,20 @@ void TestStdAllocator(const Allocator& a) {
         arr[i] = 0x0f0f0f0f;
     }
     ia.deallocate(arr, 10);
-    arr = (int *)ia.Malloc(10 * sizeof(int));
+    arr = Malloc<int>(ia, 10);
     EXPECT_TRUE(arr != 0);
     for (int i = 0; i < 10; ++i) {
         arr[i] = 0x0f0f0f0f;
     }
-    arr = (int *)ia.Realloc(arr, 10 * sizeof(int), 20 * sizeof(int));
+    arr = Realloc<int>(ia, arr, 10, 20);
     EXPECT_TRUE(arr != 0);
     for (int i = 0; i < 10; ++i) {
         EXPECT_EQ(arr[i], 0x0f0f0f0f);
     }
     for (int i = 10; i < 20; i++) {
         arr[i] = 0x0f0f0f0f;
     }
-    ia.Free(arr);
+    Free<int>(ia, arr, 20);
 
     int cons = 0, dest = 0;
     StdAllocator<TestStdAllocatorData, Allocator> da(a);