separate Input and Output impls

edn/src/edn_view.rs

@@ -1,56 +1,62 @@
 use crate::*;
 use std::marker::PhantomData;
-use ::tek_layout::{*, tek_engine::{Usually, Content, Render, RenderBox, Engine, Thunk}};
+use ::tek_layout::{*, tek_engine::{Usually, Content, Render, RenderBox, Output, Thunk}};
 use EdnItem::*;
 
-pub type EdnCallback<'a, Engine, State> =
-    dyn Fn(&'a State)-> RenderBox<'a, Engine> + Send + Sync + 'a;
+pub type EdnCallback<'a, Output, State> =
+    dyn Fn(&'a State)-> RenderBox<'a, Output> + Send + Sync + 'a;
 
-pub type EdnRenderCallback<'a, Engine, State> =
-    Box<EdnCallback<'a, Engine, State>>;
+pub type EdnRenderCallback<'a, Output, State> =
+    Box<EdnCallback<'a, Output, State>>;
 
-pub trait EdnViewData<E: Engine> {
+pub trait EdnViewData<E: Output> {
     fn get_bool    (&self, _sym: EdnItem<&str>) -> bool { false }
     fn get_unit    (&self, _sym: EdnItem<&str>) -> E::Unit { 0.into() }
     fn get_usize   (&self, _sym: EdnItem<&str>) -> usize { 0 }
-    fn get_content <'a> (&'a self, _sym: EdnItem<&str>) -> RenderBox<'a, E> { Box::new(()) }
+    fn get_content <'a> (&'a self, _sym: EdnItem<&'a str>) -> RenderBox<'a, E> { Box::new(()) }
 }
 
 /// Renders from EDN source and context.
-pub struct EdnView<E: Engine, T: EdnViewData<E>> {
-    _engine: PhantomData<E>,
-    context: T,
-    layout:  EdnItem<String>
+pub enum EdnView<E: Output, T: EdnViewData<E>> {
+    _Unused(PhantomData<E>),
+    Ok(T, EdnItem<String>),
     //render: Box<dyn Fn(&'a T)->Box<dyn Render<E> + Send + Sync + 'a> + Send + Sync + 'a>
+    Err(String)
 }
 
-impl<E: Engine, T: EdnViewData<E>> EdnView<E, T> {
+impl<E: Output, T: EdnViewData<E>> EdnView<E, T> {
     pub fn new (context: T, source: &str) -> Usually<Self> {
         let layout = EdnItem::read_one(&source)?.0;
-        Ok(Self { _engine: Default::default(), context, layout, })
+        Ok(Self::Ok(context, layout))
     }
 }
 
-impl<E: Engine, T: EdnViewData<E> + Send + Sync> Content<E> for EdnView<E, T> {
+impl<E: Output, T: EdnViewData<E> + Send + Sync> Content<E> for EdnView<E, T> {
     fn content (&self) -> impl Render<E> {
         use EdnItem::*;
-        match &self.layout {
-            Nil    => ().boxed(),
-            Sym(t) => self.context.get_content(Sym(t.as_str())).boxed(),
-            Key(t) => panic!("todo: add error handling to content() chain. unexpected key {t}"),
-            Num(n) => panic!("todo: add error handling to content() chain. unexpected num {n}"),
-            Exp(e) => if let [head, tail @ ..] = e.as_slice() {
-                let head = &head.to_ref();
-                let state = &self.context;
-                match (head, tail) {
-                    (Key("when"), [c, a])  => When(state.get_bool(c.to_ref()), state.get_content(a.to_ref())).boxed(),
-                    (Key("bsp/s"), [a, b]) => Bsp::s(state.get_content(a.to_ref()), state.get_content(b.to_ref()),).boxed(),
-                    _ => todo!("{:?} {:?}", &head, &tail)
-                }
-            } else {
-                panic!("todo: add error handling to content() chain. invalid expression {e:?}")
+        match self {
+            Self::Ok(state, layout) => match layout {
+                Nil    => ().boxed(),
+                Sym(t) => state.get_content(Sym(t.as_str())).boxed(),
+                Key(t) => panic!("todo: add error handling to content() chain. unexpected key {t}"),
+                Num(n) => panic!("todo: add error handling to content() chain. unexpected num {n}"),
+                Exp(e) => if let [head, tail @ ..] = e.as_slice() {
+                    let head = &head.to_ref();
+                    match (head, tail) {
+                        (Key("when"), [c, a])  => When(state.get_bool(c.to_ref()), state.get_content(a.to_ref())).boxed(),
+                        (Key("bsp/s"), [a, b]) => Bsp::s(state.get_content(a.to_ref()), state.get_content(b.to_ref()),).boxed(),
+                        _ => todo!("{:?} {:?}", &head, &tail)
+                    }
+                } else {
+                    panic!("todo: add error handling to content() chain. invalid expression {e:?}")
+                },
             },
+            Self::Err(error) => {
+                Box::new(())//&format!("EdnView error: {error:?}"))
+            },
+            _ => todo!()
         }
+        
         //let items = &self.layout;
         //if let (Some(first), rest) = (items.get(0).map(EdnItem::to_str), &items[1..]) {
             //match (first, rest) {