[Type] Convert is_fixed_array trait to concept

Author: alxbilger

Sofa/framework/Helper/src/sofa/helper/accessor/ReadAccessor.h

@@ -72,8 +72,8 @@ class ReadAccessor
     const_reference operator* () const { return  *vref; }
 };
 
-template<class FixedArrayLikeType>
-class ReadAccessor<FixedArrayLikeType, std::enable_if_t<sofa::type::trait::is_fixed_array<FixedArrayLikeType>::value>>
+template<sofa::type::trait::is_fixed_array FixedArrayLikeType>
+class ReadAccessor<FixedArrayLikeType>
     : public ReadAccessorFixedArray< FixedArrayLikeType >
 {
 public:

Sofa/framework/Helper/src/sofa/helper/accessor/ReadAccessorFixedArray.h

@@ -28,7 +28,7 @@ namespace sofa::helper
 {
 ////////////////////////// ReadAccessor for wrapping around fixed array like object //////////////////////
 /// ReadAccessor implementation class for fixed array types
-template<class T>
+template<type::trait::is_fixed_array T>
 class ReadAccessorFixedArray
 {
 public:

Sofa/framework/Helper/src/sofa/helper/accessor/WriteAccessor.h

@@ -83,8 +83,8 @@ class WriteAccessor
     }
 };
 
-template<class FixedArrayLikeType>
-class WriteAccessor<FixedArrayLikeType, std::enable_if_t<sofa::type::trait::is_fixed_array<FixedArrayLikeType>::value>>
+template<type::trait::is_fixed_array FixedArrayLikeType>
+class WriteAccessor<FixedArrayLikeType>
     : public WriteAccessorFixedArray< FixedArrayLikeType >
 {
 public:
@@ -95,7 +95,7 @@ class WriteAccessor<FixedArrayLikeType, std::enable_if_t<sofa::type::trait::is_f
 
 template<class VectorLikeType>
 class WriteAccessor<VectorLikeType,
-                    std::enable_if_t<sofa::type::trait::is_vector<VectorLikeType>::value>>
+                    std::enable_if_t<type::trait::is_vector<VectorLikeType>::value>>
     : public WriteAccessorVector< VectorLikeType >
 {
 public:

Sofa/framework/Helper/src/sofa/helper/accessor/WriteAccessorFixedArray.h

@@ -27,7 +27,7 @@ namespace sofa::helper
 {
 
 /// WriteAccessor implementation class for fixed array types
-template<class T>
+template<type::trait::is_fixed_array T>
 class WriteAccessorFixedArray
 {
 public:

Sofa/framework/Type/src/sofa/type/trait/is_fixed_array.h

@@ -27,39 +27,17 @@ namespace sofa::type::trait
 
 /// Detect if a type T has iterator/const iterator function, operator[](size_t) and defines a static size
 template<typename T>
-struct is_fixed_array
+concept is_fixed_array = requires(std::remove_cv_t<T> t, const std::remove_cv_t<T> ct)
 {
-    typedef typename std::remove_const<T>::type test_type;
+    T::static_size;
 
-    template<typename A>
-    static constexpr bool test(
-        A * pt,
-        A const * cpt = nullptr,
-        decltype(pt->begin()) * = nullptr,
-        decltype(pt->end()) * = nullptr,
-        decltype(cpt->begin()) * = nullptr,
-        decltype(cpt->end()) * = nullptr,
-        typename std::decay<decltype((*pt)[0])>::type * = nullptr,   ///< Is there an operator[] ?
-        decltype(A::static_size) * = nullptr, ///< fixed array containers define static_size
-        typename A::iterator * = nullptr,
-        typename A::const_iterator * = nullptr,
-        typename A::value_type * = nullptr)
-    {
+    {t.begin()} -> std::convertible_to<typename T::iterator>;
+    {t.end()} -> std::convertible_to<typename T::iterator>;
 
-        typedef typename A::iterator iterator;
-        typedef typename A::const_iterator const_iterator;
-        return  std::is_same<decltype(pt->begin()),iterator>::value
-                && std::is_same<decltype(pt->end()),iterator>::value
-                && std::is_same<decltype(cpt->begin()),const_iterator>::value
-                && std::is_same<decltype(cpt->end()),const_iterator>::value;
-    }
+    {ct.begin()} -> std::convertible_to<typename T::const_iterator>;
+    {ct.end()} -> std::convertible_to<typename T::const_iterator>;
 
-    template<typename A>
-    static constexpr bool test(...) {
-        return false;
-    }
-
-    static const bool value = test<test_type>(nullptr);
+    { t[0] } -> std::convertible_to<typename T::value_type>;
 };
 
 }