sweeeeping sweep

engine/src/output.rs

@@ -39,6 +39,60 @@ impl<E: Engine> Content<E> for () {}
 
 impl<E: Engine, T: Content<E>> Content<E> for &T {}
 
+impl<E: Engine, T: Content<E>> Content<E> for Option<T> {}
+
+#[macro_export] macro_rules! render {
+    (($self:ident:$Struct:ty) => $content:expr) => {
+        impl <E: Engine> Content<E> for $Struct {
+            fn content (&$self) -> Option<impl Content<E>> {
+                Some($content)
+            }
+        }
+    };
+    (|$self:ident:$Struct:ident $(<
+        $($L:lifetime),*
+        $($T:ident $(:$Trait:path)?),*
+    >)?, $to:ident | $render:expr) => {
+        impl <$($($L),*)? E: Engine, $($T$(:$Trait)?),*> Content<E>
+        for $Struct $(<$($L),* $($T),*>>)? {
+            fn render (&$self, $to: &mut E::Output) {
+                Some($render)
+            }
+        }
+    };
+    ($Engine:ty:
+        ($self:ident:$Struct:ident $(<$(
+            $($L:lifetime)?
+            $($T:ident)?
+            $(:$Trait:path)?
+        ),+>)?) => $content:expr
+    ) => {
+        impl $(<$($($L)? $($T)? $(:$Trait)?),+>)? Content<$Engine>
+        for $Struct $(<$($($L)? $($T)?),+>)?
+        {
+            fn content (&$self) -> Option<impl Content<$Engine>> {
+                Some($content)
+            }
+        }
+    };
+
+    ($Engine:ty:
+        |$self:ident : $Struct:ident $(<$(
+            $($L:lifetime)?
+            $($T:ident)?
+            $(:$Trait:path)?
+        ),+>)?, $to:ident| $render:expr
+    ) => {
+        impl $(<$($($L)? $($T)? $(:$Trait)?),+>)? Content<$Engine>
+        for $Struct $(<$($($L)? $($T)?),+>)?
+        {
+            fn render (&$self, $to: &mut <$Engine as Engine>::Output) {
+                Some($render)
+            }
+        }
+    };
+}
+
 //impl<E: Engine, R: Render<E>> Render<E> for &R {}
 
 //pub trait Render<E: Engine>: Send + Sync {