is()/as(): Refactor is() and as() for std::any

Author: filipsajdak

include/cpp2util.h

@@ -2082,28 +2082,22 @@ auto as(specialization_of_template<std::variant> auto&& x CPP2_SOURCE_LOCATION_P
 
 //  is Type
 //
-template<typename T, typename X>
-    requires (std::is_same_v<X,std::any> && !std::is_same_v<T,std::any> && !std::is_same_v<T,empty>)
-constexpr auto is( X const& x ) -> bool
-    { return x.type() == Typeid<T>(); }
-
-template<typename T, typename X>
-    requires (std::is_same_v<X,std::any> && std::is_same_v<T,empty>)
-constexpr auto is( X const& x ) -> bool
-    { return !x.has_value(); }
-
+template<typename T, std::same_as<std::any> X>
+constexpr auto is( X const& x ) -> bool{
+    if (!x.has_value()) {
+        return std::is_same_v<T,empty>;
+    }
+    return x.type() == Typeid<T>(); 
+}
 
 //  is Value
 //
 inline constexpr auto is( std::any const& x, auto&& value ) -> bool
 {
     //  Predicate case
-    if constexpr (requires{ bool{ value(x) }; }) {
+    if constexpr (valid_predicate<decltype(value), decltype(x)>) {
         return value(x);
     }
-    else if constexpr (std::is_function_v<decltype(value)> || requires{ &value.operator(); }) {
-        return false;
-    }
 
     //  Value case
     else if constexpr (requires{ bool{ *std::any_cast<CPP2_TYPEOF(value)>(&x) == value }; }) {
@@ -2117,10 +2111,12 @@ inline constexpr auto is( std::any const& x, auto&& value ) -> bool
 
 //  as
 //
-template<typename T, typename X>
-    requires (!std::is_reference_v<T> && std::is_same_v<X,std::any> && !std::is_same_v<T,std::any>)
-constexpr auto as( X const& x ) -> T
-    { return std::any_cast<T>( x ); }
+template<typename T, same_type_as<std::any> X>
+constexpr auto as( X && x ) -> decltype(auto) {
+    constness_like_t<T, X>* ptr = std::any_cast<T>( &x );
+    if (!ptr) { Throw( std::bad_any_cast(), "'as' cast failed for 'std::any'"); }
+    return cpp2::forward_like<X>(*ptr);
+}
 
 
 //-------------------------------------------------------------------------------------------------------------