* Improved handling of getter and setter

* Implemented helper to check if a generic_predicate can be executed with certain values

include/cppmp/misc/generic_predicate.h

@@ -1,10 +1,26 @@
 #pragma once
 
 #include <cppmp/core/types.h>
+#include <cppmp/core/checker.h>
 
 namespace cppmp
 {
 
+    namespace __impl
+    {
+
+        template<typename X, typename = void>
+        struct is_valid_builder
+            : public cppmp::true_t
+            { };
+
+        template<typename X>
+        struct is_valid_builder<X, cppmp::void_t<typename X::is_default>>
+            : public cppmp::false_t
+            { };
+
+    }
+
     /**
      * @brief Helper class to create generic predicates.
      *
@@ -13,6 +29,20 @@ namespace cppmp
     template<template<typename...> class T_builder>
     struct generic_predicate
     {
+        /**
+         * @brief Helper class to check if the passed arguments would create a valid object.
+         */
+        template<typename... T_args>
+        struct is_valid
+            : public __impl::is_valid_builder<T_builder<list<T_args...>>>
+            { };
+
+        /**
+         * @brief Evaluates to true if the passed arguments would create a valid object, false otherwise.
+         */
+        template<typename... T_args>
+        static constexpr bool is_valid_v = is_valid<T_args...>::value;
+
         /**
          * @brief Invoke the builder to create the requested object.
          *

include/cppmp/misc/getter.h

@@ -5,12 +5,16 @@
 namespace cppmp
 {
 
-    namespace __impl
-    {
+    /* tags */
 
-        /* tag_getter */
+    struct tag_getter { };
+    struct tag_getter_member_var { };
+    struct tag_getter_member_func { };
+    struct tag_getter_lambda { };
+    struct tag_getter_chain { };
 
-        struct tag_getter;
+    namespace __impl
+    {
 
         /* getter_builder */
 

include/cppmp/misc/getter.inl

@@ -11,16 +11,13 @@ namespace cppmp
     namespace __impl
     {
 
-        /* tag_getter */
-
-        struct tag_getter
-            { };
-
         /* getter_builder - default */
 
         template<typename X, typename>
         struct getter_builder
         {
+            using is_default = cppmp::true_t;
+
             template<typename... T_args>
             static constexpr decltype(auto) apply(T_args&&...)
                 { static_assert(sizeof...(T_args) == -1, "Invalid parameters for make_getter(...)!"); }
@@ -46,6 +43,7 @@ namespace cppmp
         {
             struct getter_member_var
                 : public tag_getter
+                , public tag_getter_member_var
             {
                 using object_type = T_object;
                 using value_type  = T_value;
@@ -83,9 +81,10 @@ namespace cppmp
         {
             struct getter_member_func
                 : public tag_getter
+                , public tag_getter_member_func
             {
-                using object_type = decay_t<T_object>;
-                using value_type  = decay_t<T_value>;
+                using object_type = T_object;
+                using value_type  = T_value;
                 using member_type = T_member;
 
                 member_type member;
@@ -124,7 +123,7 @@ namespace cppmp
         struct getter_builder<
             list<T_value (T_object::*)() const>,
             void>
-            : public getter_builder_member_func<T_object, T_value, T_value (T_object::*)() const>
+            : public getter_builder_member_func<const T_object, T_value, T_value (T_object::*)() const>
             { };
 
         /* getter_builder - lambda/static */
@@ -139,11 +138,12 @@ namespace cppmp
         {
             struct getter_lambda
                 : public tag_getter
+                , public tag_getter_lambda
             {
                 using lambda_type        = T_lambda;
                 using lambda_traits_type = lambda_traits<lambda_type>;
-                using object_type        = decay_t<typename lambda_traits_type::template argument_t<0>>;
-                using value_type         = decay_t<typename lambda_traits_type::return_type>;
+                using object_type        = typename lambda_traits_type::template argument_t<0>;
+                using value_type         = typename lambda_traits_type::return_type;
 
                 lambda_type lambda;
 
@@ -181,6 +181,7 @@ namespace cppmp
         {
             struct getter_chain
                 : public tag_getter
+                , public tag_getter_chain
             {
                 using first_getter_type  = decltype(make_getter(std::declval<T_first>()));
                 using second_getter_type = decltype(make_getter(std::declval<T_second>(), std::declval<T_rest>()...));
@@ -223,7 +224,7 @@ namespace cppmp
 
     template<typename T>
     struct is_getter
-        : public is_base_of<__impl::tag_getter, T>
+        : public is_base_of<tag_getter, T>
         { };
 
 }

include/cppmp/misc/setter.h

@@ -5,12 +5,15 @@
 namespace cppmp
 {
 
-    namespace __impl
-    {
+    /* tags */
 
-        /* tag_setter */
+    struct tag_setter { };
+    struct tag_setter_member_var { };
+    struct tag_setter_member_func { };
+    struct tag_setter_lambda { };
 
-        struct tag_setter;
+    namespace __impl
+    {
 
         /* setter_builder */
 

include/cppmp/misc/setter.inl

@@ -10,16 +10,13 @@ namespace cppmp
     namespace __impl
     {
 
-        /* tag_setter */
-
-        struct tag_setter
-            { };
-
         /* setter_builder - default */
 
         template<typename X, typename>
         struct setter_builder
         {
+            using is_default = cppmp::true_t;
+
             template<typename... T_args>
             static constexpr decltype(auto) apply(T_args&&...)
                 { static_assert(sizeof...(T_args) == -1, "Invalid parameters for make_setter(...)!"); }
@@ -45,6 +42,7 @@ namespace cppmp
         {
             struct setter_member_var
                 : public tag_setter
+                , public tag_setter_member_var
             {
                 using object_type = T_object;
                 using value_type  = T_value;
@@ -82,9 +80,10 @@ namespace cppmp
         {
             struct setter_member_func
                 : public tag_setter
+                , public tag_setter_member_func
             {
-                using object_type = decay_t<T_object>;
-                using value_type  = decay_t<T_value>;
+                using object_type = T_object;
+                using value_type  = T_value;
                 using member_type = T_member;
 
                 member_type member;
@@ -123,7 +122,7 @@ namespace cppmp
         struct setter_builder<
             list<void (T_object::*)(T_value) const>,
             void>
-            : public setter_builder_member_func<T_object, T_value, void (T_object::*)(T_value) const>
+            : public setter_builder_member_func<const T_object, T_value, void (T_object::*)(T_value) const>
             { };
 
         /* setter_builder - lambda/static */
@@ -137,11 +136,12 @@ namespace cppmp
         {
             struct setter_lambda
                 : public tag_setter
+                , public tag_setter_lambda
             {
                 using lambda_type        = T_lambda;
                 using lambda_traits_type = lambda_traits<lambda_type>;
-                using object_type        = decay_t<typename lambda_traits_type::template argument_t<0>>;
-                using value_type         = decay_t<typename lambda_traits_type::template argument_t<1>>;
+                using object_type        = typename lambda_traits_type::template argument_t<0>;
+                using value_type         = typename lambda_traits_type::template argument_t<1>;
 
                 lambda_type lambda;
 
@@ -172,7 +172,7 @@ namespace cppmp
 
     template<typename T>
     struct is_setter
-        : public is_base_of<__impl::tag_setter, T>
+        : public is_base_of<tag_setter, T>
         { };
 
 }