enable and patch up mod eval

src/draw.rs

@@ -1,6 +1,12 @@
 use crate::{*, lang::*, color::*, space::*};
 
 /// Drawable that supports dynamic dispatch.
+///
+/// Drawables are composable, e.g. the [when] and [either] conditionals
+/// or the layout constraints.
+///
+/// Drawables are consumable, i.e. the [Draw::draw] method receives an
+/// owned `self` and does not return it, consuming the drawable.
 /// 
 /// ```
 /// use tengri::draw::*;
@@ -20,25 +26,29 @@ use crate::{*, lang::*, color::*, space::*};
 pub trait Draw<T: Screen> {
     fn draw (self, to: &mut T) -> Usually<XYWH<T::Unit>>;
 }
+
 impl<T: Screen> Draw<T> for () {
     fn draw (self, __: &mut T) -> Usually<XYWH<T::Unit>> {
         Ok(Default::default())
     }
 }
+
 impl<T: Screen, D: Draw<T>> Draw<T> for Option<D> {
     fn draw (self, to: &mut T) -> Usually<XYWH<T::Unit>> {
         Ok(self.map(|draw|draw.draw(to)).transpose()?.unwrap_or_default())
     }
 }
 
+pub const fn thunk <T: Screen, F: FnOnce(&mut T)->Usually<XYWH<T::Unit>>> (draw: F) -> Thunk<T, F> {
+    Thunk(draw, std::marker::PhantomData)
+}
+
 /// Because we can't implement [Draw] for `F: FnOnce...` without conflicts.
 pub struct Thunk<T: Screen, F: FnOnce(&mut T)->Usually<XYWH<T::Unit>>>(
     pub F,
     std::marker::PhantomData<T>
 );
-pub const fn thunk <T: Screen, F: FnOnce(&mut T)->Usually<XYWH<T::Unit>>> (draw: F) -> Thunk<T, F> {
+
-    Thunk(draw, std::marker::PhantomData)
-}
 impl<T: Screen, F: FnOnce(&mut T)->Usually<XYWH<T::Unit>>> Draw<T> for Thunk<T, F> {
     fn draw (self, to: &mut T) -> Usually<XYWH<T::Unit>> {
         (self.0)(to)
@@ -76,8 +86,8 @@ pub const fn either <T: Screen> (condition: bool, a: impl Draw<T>, b: impl Draw<
 ///
 /// impl Screen for TestOut {
 ///     type Unit = u16;
-///     fn place <T: Draw<Self> + ?Sized> (&mut self, area: impl TwoD<u16>, _: &T) {
+///     fn place_at <T: Draw<Self> + ?Sized> (&mut self, area: impl TwoD<u16>, _: &T) {
-///         println!("place: {area:?}");
+///         println!("placed: {area:?}");
 ///         ()
 ///     }
 /// }
@@ -101,3 +111,14 @@ pub trait Screen: Space<Self::Unit> + Send + Sync + Sized {
         unimplemented!()
     }
 }
+
+/// Emit a [Draw]able.
+pub trait View<T: Screen> {
+    fn view (&self) -> impl Draw<T>;
+}
+
+impl<T: Screen, V: View<T>> Draw<T> for &V {
+    fn draw (self, to: &mut T) -> Usually<XYWH<T::Unit>> {
+        self.view().draw(to)
+    }
+}

src/eval.rs

@@ -1,4 +1,5 @@
-use crate::*;
+use crate::{*, term::*, draw::*, ratatui::prelude::*};
+use dizzle::*;
 
 /// Interpret layout operation.
 ///
@@ -165,7 +166,7 @@ use crate::*;
 /// impl     Understand<Tui, ()> for State {}
 /// # fn main () -> tengri::Usually<()> {
 /// let state = State;
-/// let mut out = TuiOut::default();
+/// let mut out = Tui::default();
 /// tengri::eval_view_tui(&state, &mut out, "")?;
 /// tengri::eval_view_tui(&state, &mut out, "text Hello world!")?;
 /// tengri::eval_view_tui(&state, &mut out, "fg (g 0) (text Hello world!)")?;
@@ -174,9 +175,9 @@ use crate::*;
 /// # Ok(()) }
 /// ```
 pub fn eval_view_tui <'a, S> (
-    state: &S, output: &mut Buffer, expr: impl Expression + 'a
+    state: &S, output: &mut Tui, expr: impl Expression + 'a
 ) -> Usually<bool> where
-    S: Understand<TuiOut, ()>
+    S: Understand<Tui, ()>
         + for<'b>Namespace<'b, bool>
         + for<'b>Namespace<'b, u16>
         + for<'b>Namespace<'b, Color>
@@ -199,18 +200,21 @@ pub fn eval_view_tui <'a, S> (
         Some("fg") => {
             let arg0  = arg0?.expect("fg: expected arg 0 (color)");
             let color = Namespace::namespace(state, arg0)?.unwrap_or_else(||panic!("fg: {arg0:?}: not a color"));
-            let thunk = Thunk::new(move|output: &mut Buffer|state.understand(output, &arg1).unwrap());
+            output.place(&fg(color, thunk(move|output: &mut Tui|{
-            output.place(&TuiOut::fg(color, thunk))
+                state.understand(output, &arg1)?;
+                // FIXME?: don't max out the used area?
+                Ok(output.area().into())
+            })))
         },
 
         Some("bg") => {
-            //panic!("expr: {expr:?}\nhead: {head:?}\nfrags: {frags:?}\nargs: {args:?}\narg0: {arg0:?}\ntail0: {tail0:?}\narg1: {arg1:?}\ntail1: {tail1:?}\narg2: {arg2:?}");
-            //panic!("head: {head:?}\narg0: {arg0:?}\narg1: {arg1:?}\narg2: {arg2:?}");;
-            //panic!("head: {head:?}\narg0: {arg0:?}\narg1: {arg1:?}\narg2: {arg2:?}");
             let arg0  = arg0?.expect("bg: expected arg 0 (color)");
             let color = Namespace::namespace(state, arg0)?.unwrap_or_else(||panic!("bg: {arg0:?}: not a color"));
-            let thunk = Thunk::new(move|output: &mut Buffer|state.understand(output, &arg1).unwrap());
+            output.place(&bg(color, thunk(move|output: &mut Tui|{
-            output.place(&TuiOut::bg(color, thunk))
+                state.understand(output, &arg1)?;
+                // FIXME?: don't max out the used area?
+                Ok(output.area().into())
+            })))
         },
 
         _ => return Ok(false)

src/exit.rs

@@ -0,0 +1,10 @@
+use std::sync::{Arc, atomic::AtomicBool};
+use crate::Usually;
+
+#[derive(Clone)] pub struct Exit(Arc<AtomicBool>);
+
+impl Exit {
+    pub fn run <T> (run: impl Fn(Self)->Usually<T>) -> Usually<T> {
+        run(Self(Arc::new(AtomicBool::new(false))))
+    }
+}

src/keys.rs

@@ -1,4 +1,4 @@
-use crate::play::Thread;
+use crate::task::Task;
 
 use ::std::sync::{Arc, RwLock, atomic::{AtomicBool, Ordering::*}};
 use ::std::time::Duration;
@@ -10,10 +10,10 @@ use ::crossterm::event::{
 /// Spawn the TUI input thread which reads keys from the terminal.
 pub fn tui_input <T: Do<TuiEvent, Usually<T>> + Send + Sync + 'static> (
     exited: &Arc<AtomicBool>, state: &Arc<RwLock<T>>, poll: Duration
-) -> Result<Thread, std::io::Error> {
+) -> Result<Task, std::io::Error> {
     let exited = exited.clone();
     let state = state.clone();
-    Thread::new_poll(exited.clone(), poll, move |_| {
+    Task::new_poll(exited.clone(), poll, move |_| {
         let event = read().unwrap();
         match event {
 

src/lib.rs

@@ -25,9 +25,14 @@ pub(crate) use ::{
 
 #[cfg(feature = "lang")] pub extern crate dizzle as lang;
 #[cfg(feature = "lang")] pub use ::dizzle::{self, Usually, Perhaps, impl_default};
+#[cfg(feature = "lang")] pub mod eval;
 
 #[cfg(feature = "time")] pub mod time;
+
 #[cfg(feature = "play")] pub mod play;
+#[cfg(feature = "play")] pub mod exit;
+#[cfg(feature = "play")] pub mod task;
+
 #[cfg(feature = "sing")] pub extern crate jack;
 #[cfg(feature = "sing")] pub mod sing;
 #[cfg(feature = "sing")] pub use ::jack::{*, contrib::{*, ClosureProcessHandler}};

src/play.rs

@@ -1,65 +1,5 @@
 use crate::{*, time::*, lang::*};
 use ::std::{thread::JoinHandle, time::Duration};
-#[cfg(feature = "term")] use ::crossterm::event::poll;
-
-#[derive(Clone)] pub struct Exit(Arc<AtomicBool>);
-
-impl Exit {
-    pub fn run <T> (run: impl Fn(Self)->Usually<T>) -> Usually<T> {
-        run(Self(Arc::new(AtomicBool::new(false))))
-    }
-}
-
-#[derive(Debug)] pub struct Thread {
-    /// Exit flag.
-    pub exit: Arc<AtomicBool>,
-    /// Performance counter.
-    pub perf: Arc<PerfModel>,
-    /// Use this to wait for the thread to finish.
-    pub join: JoinHandle<()>,
-}
-
-impl Thread {
-    /// Spawn a TUI thread that runs `callt least one, then repeats until `exit`.
-    pub fn new <F> (exit: Arc<AtomicBool>, mut call: F) -> Result<Self, std::io::Error>
-        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
-    {
-        let perf = Arc::new(PerfModel::default());
-        Ok(Self {
-            exit: exit.clone(),
-            perf: perf.clone(),
-            join: std::thread::Builder::new().name("tengri tui output".into()).spawn(move || {
-                while !exit.fetch_and(true, Relaxed) {
-                    let _ = perf.cycle(&mut call);
-                }
-            })?.into()
-        })
-    }
-
-    /// Spawn a thread that runs `call` least one, then repeats
-    /// until `exit`, sleeping for `time` msec after every iteration.
-    pub fn new_sleep <F> (
-        exit: Arc<AtomicBool>, time: Duration, mut call: F
-    ) -> Result<Self, std::io::Error>
-        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
-    {
-        Self::new(exit, move |perf| { let _ = call(perf); std::thread::sleep(time); })
-    }
-
-    /// Spawn a thread that uses [crossterm::event::poll]
-    /// to run `call` every `time` msec.
-    #[cfg(feature = "term")] pub fn new_poll <F> (
-        exit: Arc<AtomicBool>, time: Duration, mut call: F
-    ) -> Result<Self, std::io::Error>
-        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
-    {
-        Self::new(exit, move |perf| { if poll(time).is_ok() { let _ = call(perf); } })
-    }
-
-    pub fn join (self) -> Result<(), Box<dyn std::any::Any + Send>> {
-        self.join.join()
-    }
-}
 
 /// Define an enum containing commands, and implement [Command] trait for over given `State`.
 #[macro_export] macro_rules! def_command (
@@ -82,7 +22,7 @@ impl Thread {
     });
 
 /// Implement [Handle] for given `State` and `handler`.
-#[macro_export] macro_rules! handle {
+#[macro_export] macro_rules! impl_handle {
     (|$self:ident:$State:ty,$input:ident|$handler:expr) => {
         impl<E: Engine> ::tengri::Handle<E> for $State {
             fn handle (&mut $self, $input: &E) -> Perhaps<E::Handled> {

src/space.rs

@@ -11,6 +11,11 @@ use crate::{*, draw::*};
 ///
 #[cfg_attr(test, derive(Arbitrary))] #[derive(Copy, Clone, Debug, Default, PartialEq)]
 pub struct XYWH<N: Coord>(pub N, pub N, pub N, pub N);
+impl From<&ratatui::prelude::Rect> for XYWH<u16> {
+    fn from (rect: &ratatui::prelude::Rect) -> Self {
+        Self(rect.x, rect.y, rect.width, rect.height)
+    }
+}
 impl<N: Coord> X<N> for XYWH<N> { fn x (&self) -> N { self.0 } fn w (&self) -> N { self.2 } }
 impl<N: Coord> Y<N> for XYWH<N> { fn y (&self) -> N { self.0 } fn h (&self) -> N { self.2 } }
 impl<N: Coord> XYWH<N> {

src/task.rs

@@ -0,0 +1,65 @@
+use std::{
+    time::Duration,
+    sync::{Arc, atomic::{AtomicBool, Ordering::*}},
+    thread::{Builder, JoinHandle, sleep},
+};
+#[cfg(feature = "term")] use ::crossterm::event::poll;
+use crate::time::PerfModel;
+
+#[derive(Debug)] pub struct Task {
+    /// Exit flag.
+    pub exit: Arc<AtomicBool>,
+    /// Performance counter.
+    pub perf: Arc<PerfModel>,
+    /// Use this to wait for the thread to finish.
+    pub join: JoinHandle<()>,
+}
+
+impl Task {
+    /// Spawn a TUI thread that runs `callt least one, then repeats until `exit`.
+    pub fn new <F> (exit: Arc<AtomicBool>, mut call: F) -> Result<Self, std::io::Error>
+        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
+    {
+        let perf = Arc::new(PerfModel::default());
+        Ok(Self {
+            exit: exit.clone(),
+            perf: perf.clone(),
+            join: Builder::new().name("tengri tui output".into()).spawn(move || {
+                while !exit.fetch_and(true, Relaxed) {
+                    let _ = perf.cycle(&mut call);
+                }
+            })?.into()
+        })
+    }
+
+    /// Spawn a thread that runs `call` least one, then repeats
+    /// until `exit`, sleeping for `time` msec after every iteration.
+    pub fn new_sleep <F> (
+        exit: Arc<AtomicBool>, time: Duration, mut call: F
+    ) -> Result<Self, std::io::Error>
+        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
+    {
+        Self::new(exit, move |perf| {
+            let _ = call(perf);
+            sleep(time);
+        })
+    }
+
+    /// Spawn a thread that uses [crossterm::event::poll]
+    /// to run `call` every `time` msec.
+    #[cfg(feature = "term")] pub fn new_poll <F> (
+        exit: Arc<AtomicBool>, time: Duration, mut call: F
+    ) -> Result<Self, std::io::Error>
+        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
+    {
+        Self::new(exit, move |perf| {
+            if poll(time).is_ok() {
+                let _ = call(perf);
+            }
+        })
+    }
+
+    pub fn join (self) -> Result<(), Box<dyn std::any::Any + Send>> {
+        self.join.join()
+    }
+}

src/term.rs

@@ -1,4 +1,4 @@
-use crate::{*, lang::*, play::*, draw::*, space::{*, Split::*}, color::*, text::*};
+use crate::{*, lang::*, play::*, draw::*, space::{*, Split::*}, color::*, text::*, task::*};
 use unicode_width::{UnicodeWidthStr, UnicodeWidthChar};
 use rand::distributions::uniform::UniformSampler;
 use ::{
@@ -509,14 +509,14 @@ pub fn tui_output <W: Write + Send + Sync + 'static, T: Draw<Tui> + Send + Sync
     exited: &Arc<AtomicBool>,
     state:  &Arc<RwLock<T>>,
     sleep:  Duration
-) -> Usually<Thread> {
+) -> Usually<Task> {
     let state = state.clone();
     tui_setup()?;
     let mut backend = CrosstermBackend::new(output);
     let Size { width, height } = backend.size().expect("get size failed");
     let mut buffer_a = Buffer::empty(Rect { x: 0, y: 0, width, height });
     let mut buffer_b = Buffer::empty(Rect { x: 0, y: 0, width, height });
-    Ok(Thread::new_sleep(exited.clone(), sleep, move |perf| {
+    Ok(Task::new_sleep(exited.clone(), sleep, move |perf| {
         let Size { width, height } = backend.size().expect("get size failed");
         if let Ok(state) = state.try_read() {
             tui_resize(&mut backend, &mut buffer_a, Rect { x: 0, y: 0, width, height });

src/text.rs

@@ -17,12 +17,12 @@ pub(crate) use ::unicode_width::*;
             self.as_str().draw(to)
         }
     }
-    impl Draw<Tui> for &std::sync::Arc<str> {
+    impl Draw<Tui> for std::sync::Arc<str> {
         fn draw (self, to: &mut Tui) -> Usually<XYWH<u16>> {
             self.as_ref().draw(to)
         }
     }
-    impl Draw<Tui> for std::sync::Arc<str> {
+    impl Draw<Tui> for &std::sync::Arc<str> {
         fn draw (self, to: &mut Tui) -> Usually<XYWH<u16>> {
             self.as_ref().draw(to)
         }