Structure the concept of APIs

examples/Counter.cpp

@@ -5,11 +5,15 @@
 namespace props::counter
 {
 auto is_dark_theme = fallback<bool>(false);
-}
+
+auto all = is_dark_theme;
+} // namespace props::counter
 namespace state::counter
 {
 State<int> count;
-}
+
+auto all = count;
+} // namespace state::counter
 namespace msg
 {
 Message<int> increment;
@@ -22,19 +26,27 @@ ShouldRender update()
     using namespace msg;
     if (increment)
     {
-        count += increment.get<0>();
+        *count += increment.get<0>();
         return true;
     }
     if (decrement)
     {
-        count -= decrement.get<0>();
+        *count -= decrement.get<0>();
     }
     return true;
 }
 
+VNode render()
+{
+    return 0;
+}
+
+auto counter = create_component(props::counter::all, state::counter::all, update, render);
+
 int main()
 {
     using namespace props::counter;
+    counter(is_dark_theme = true)("Hello, world!");
     // new Counter(is_dark_theme = true);
     // Counter{is_dark_theme = true};
     // Counter(is_dark_theme = true);

include/spaic/Component.hpp

@@ -1,17 +1,30 @@
 #pragma once
 
 #include <functional>
+#include <variant>
+#include <spaic/VNode.hpp>
+#include <spaic/Property.hpp>
+#include <spaic/State.hpp>
 
 namespace spaic::comp
 {
 using ShouldRender = bool;
-template <typename State, typename Msg>
-using Update = std::function(Msg)->ShouldRender;
+using Update = std::function<ShouldRender()>;
+using Render = std::function<spaic::vnode::VNode()>;
 
-template <typename Props, typename State>
+class ComponentBody;
+template <typename Props>
 class Component
 {
+public:
+    template <typename... T>
+    ComponentBody operator()(T... args) noexcept;
 };
-template <typename Props, typename State>
-Component<Props, State> create_component(Props props, State state);
-} // namespace spaic
+class ComponentBody
+{
+public:
+    spaic::vnode::VNode operator()(spaic::vnode::VNode children...) noexcept;
+};
+template <typename Props, typename StateSet>
+Component<Props> create_component(Props props, StateSet state, Update update, Render render);
+} // namespace spaic::comp

include/spaic/Message.hpp

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <tuple>
+
 namespace spaic::msg
 {
 template <typename... T>
@@ -11,7 +13,7 @@ class Message
     operator bool();
 
     template <size_t I>
-    std::tuple_element<I, T...> get();
+    typename std::tuple_element<I, std::tuple<T...>>::type get();
 };
 
 } // namespace spaic::msg

include/spaic/Prelude.hpp

@@ -9,3 +9,4 @@ using namespace spaic::props;
 using namespace spaic::msg;
 using namespace spaic::state;
 using namespace spaic::comp;
+using namespace spaic::vnode;

include/spaic/State.hpp

@@ -7,5 +7,8 @@ class State
 {
 public:
     State() {}
+
+    // todo:
+    T &operator*();
 };
 } // namespace spaic::state

include/spaic/VNode.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <variant>
+#include <string>
+#include <vector>
+
+namespace spaic::vnode
+{
+using VNode = std::variant<
+    std::string,
+    std::nullptr_t,
+    bool,
+    short,
+    unsigned short,
+    int,
+    unsigned int,
+    long,
+    unsigned long,
+    long long,
+    unsigned long long,
+    char,
+    signed char,
+    unsigned char,
+    wchar_t,
+    char16_t,
+    char32_t,
+    float,
+    double,
+    long double>;
+} // namespace spaic::vnode