dsl, output: error handlers

dsl/src/dsl_provide.rs

@@ -1,34 +1,34 @@
 use crate::*;
 
 pub trait Dsl<Type> {
-    fn take <'source> (&self, token: &mut TokenIter<'source>) -> Perhaps<Type>;
-    fn take_or_fail <'source> (
-        &self, token: &mut TokenIter<'source>, error: impl Into<Box<dyn std::error::Error>>
+    fn take <'source> (&self, words: &mut TokenIter<'source>) -> Perhaps<Type>;
+    fn take_or_fail <'source, E: Into<Box<dyn std::error::Error>>, F: Fn()->E> (
+        &self, words: &mut TokenIter<'source>, error: F
     ) -> Usually<Type> {
-        if let Some(value) = Dsl::<Type>::take(self, token)? {
+        if let Some(value) = Dsl::<Type>::take(self, words)? {
             Ok(value)
         } else {
-            Result::Err(error.into())
+            Result::Err(format!("{}: {:?}", error().into(), words.peek().map(|x|x.value)).into())
         }
     }
 }
 
 impl<Type: Namespace<State>, State> Dsl<Type> for State {
-    fn take <'source> (&self, token: &mut TokenIter<'source>) -> Perhaps<Type> {
-        Namespace::take_from(self, token)
+    fn take <'source> (&self, words: &mut TokenIter<'source>) -> Perhaps<Type> {
+        Namespace::take_from(self, words)
     }
 }
 
 pub trait Namespace<State>: Sized {
-    fn take_from <'source> (state: &State, token: &mut TokenIter<'source>)
+    fn take_from <'source> (state: &State, words: &mut TokenIter<'source>)
         -> Perhaps<Self>;
-    fn take_from_or_fail <'source> (
-        state: &State, token: &mut TokenIter<'source>, error: impl Into<Box<dyn std::error::Error>>
+    fn take_from_or_fail <'source, E: Into<Box<dyn std::error::Error>>, F: Fn()->E> (
+        state: &State, words: &mut TokenIter<'source>, error: F
     ) -> Usually<Self> {
-        if let Some(value) = Namespace::<State>::take_from(state, token)? {
+        if let Some(value) = Namespace::<State>::take_from(state, words)? {
             Ok(value)
         } else {
-            Result::Err(error.into())
+            Result::Err(format!("{}: {:?}", error().into(), words.peek().map(|x|x.value)).into())
         }
     }
 }

output/src/lib.rs

@@ -1,190 +1,10 @@
 #![feature(step_trait)]
 #![feature(type_alias_impl_trait)]
 #![feature(impl_trait_in_assoc_type)]
-//#![feature(impl_trait_in_fn_trait_return)]
-
+pub(crate) use tengri_core::*;
+pub(crate) use std::marker::PhantomData;
+#[cfg(feature = "dsl")] pub(crate) use ::tengri_dsl::*;
 mod space;   pub use self::space::*;
 mod ops;     pub use self::ops::*;
 mod output;  pub use self::output::*;
-
-pub(crate) use tengri_core::*;
-pub(crate) use std::marker::PhantomData;
-
-#[cfg(feature = "dsl")] pub(crate) use ::tengri_dsl::*;
-#[cfg(feature = "dsl")] mod view;
-#[cfg(feature = "dsl")] pub use self::view::*;
-
-#[cfg(test)] use proptest_derive::Arbitrary;
-
-#[cfg(test)] #[test] fn test_stub_output () -> Usually<()> {
-    use crate::*;
-    struct TestOutput([u16;4]);
-    impl Output for TestOutput {
-        type Unit = u16;
-        type Size = [u16;2];
-        type Area = [u16;4];
-        fn area (&self) -> [u16;4] {
-            self.0
-        }
-        fn area_mut (&mut self) -> &mut [u16;4] {
-            &mut self.0
-        }
-        fn place (&mut self, _: [u16;4], _: &impl Render<TestOutput>) {
-            ()
-        }
-    }
-    impl Content<TestOutput> for String {
-        fn render (&self, to: &mut TestOutput) {
-            to.area_mut().set_w(self.len() as u16);
-        }
-    }
-    Ok(())
-}
-
-#[cfg(test)] #[test] fn test_space () {
-    use crate::*;
-    assert_eq!(Area::center(&[10u16, 10, 20, 20]), [20, 20]);
-}
-
-#[cfg(test)] #[test] fn test_iter_map () {
-    struct Foo;
-    impl<T: Output> Content<T> for Foo {}
-    fn make_map <T: Output, U: Content<T> + Send + Sync> (data: &Vec<U>) -> impl Content<T> {
-        Map::new(||data.iter(), |foo, index|{})
-    }
-    let data = vec![Foo, Foo, Foo];
-    //let map = make_map(&data);
-}
-
-#[cfg(test)] mod test {
-    use crate::*;
-    use proptest::{prelude::*, option::of};
-
-    proptest! {
-        #[test] fn proptest_direction (
-            d in prop_oneof![
-                Just(North), Just(South),
-                Just(East),  Just(West),
-                Just(Above), Just(Below)
-            ],
-            x in u16::MIN..u16::MAX,
-            y in u16::MIN..u16::MAX,
-            w in u16::MIN..u16::MAX,
-            h in u16::MIN..u16::MAX,
-            a in u16::MIN..u16::MAX,
-        ) {
-            let _ = d.split_fixed([x, y, w, h], a);
-        }
-    }
-
-    proptest! {
-        #[test] fn proptest_size (
-            x in u16::MIN..u16::MAX,
-            y in u16::MIN..u16::MAX,
-            a in u16::MIN..u16::MAX,
-            b in u16::MIN..u16::MAX,
-        ) {
-            let size = [x, y];
-            let _ = size.w();
-            let _ = size.h();
-            let _ = size.wh();
-            let _ = size.clip_w(a);
-            let _ = size.clip_h(b);
-            let _ = size.expect_min(a, b);
-            let _ = size.to_area_pos();
-            let _ = size.to_area_size();
-        }
-    }
-
-    proptest! {
-        #[test] fn proptest_area (
-            x in u16::MIN..u16::MAX,
-            y in u16::MIN..u16::MAX,
-            w in u16::MIN..u16::MAX,
-            h in u16::MIN..u16::MAX,
-            a in u16::MIN..u16::MAX,
-            b in u16::MIN..u16::MAX,
-        ) {
-            let _: [u16;4] = <[u16;4] as Area<u16>>::zero();
-            let _: [u16;4] = <[u16;4] as Area<u16>>::from_position([a, b]);
-            let _: [u16;4] = <[u16;4] as Area<u16>>::from_size([a, b]);
-            let area: [u16;4] = [x, y, w, h];
-            let _ = area.expect_min(a, b);
-            let _ = area.xy();
-            let _ = area.wh();
-            let _ = area.xywh();
-            let _ = area.clip_h(a);
-            let _ = area.clip_w(b);
-            let _ = area.clip([a, b]);
-            let _ = area.set_w(a);
-            let _ = area.set_h(b);
-            let _ = area.x2();
-            let _ = area.y2();
-            let _ = area.lrtb();
-            let _ = area.center();
-            let _ = area.center_x(a);
-            let _ = area.center_y(b);
-            let _ = area.center_xy([a, b]);
-            let _ = area.centered();
-        }
-    }
-
-    macro_rules! test_op_transform {
-        ($fn:ident, $Op:ident) => {
-            proptest! {
-                #[test] fn $fn (
-                    op_x in of(u16::MIN..u16::MAX),
-                    op_y in of(u16::MIN..u16::MAX),
-                    content in "\\PC*",
-                    x in u16::MIN..u16::MAX,
-                    y in u16::MIN..u16::MAX,
-                    w in u16::MIN..u16::MAX,
-                    h in u16::MIN..u16::MAX,
-                ) {
-                    if let Some(op) = match (op_x, op_y) {
-                        (Some(x), Some(y)) => Some($Op::xy(x, y, content)),
-                        (Some(x), None)    => Some($Op::x(x, content)),
-                        (Some(y), None)    => Some($Op::y(y, content)),
-                        _ => None
-                    } {
-                        assert_eq!(Content::layout(&op, [x, y, w, h]),
-                                   Render::layout(&op,  [x, y, w, h]));
-                    }
-                }
-            }
-        }
-    }
-
-    test_op_transform!(proptest_op_fixed,   Fixed);
-    test_op_transform!(proptest_op_min,     Min);
-    test_op_transform!(proptest_op_max,     Max);
-    test_op_transform!(proptest_op_push,    Push);
-    test_op_transform!(proptest_op_pull,    Pull);
-    test_op_transform!(proptest_op_shrink,  Shrink);
-    test_op_transform!(proptest_op_expand,  Expand);
-    test_op_transform!(proptest_op_margin,  Margin);
-    test_op_transform!(proptest_op_padding, Padding);
-
-    proptest! {
-        #[test] fn proptest_op_bsp (
-            d in prop_oneof![
-                Just(North), Just(South),
-                Just(East),  Just(West),
-                Just(Above), Just(Below)
-            ],
-            a in "\\PC*",
-            b in "\\PC*",
-            x in u16::MIN..u16::MAX,
-            y in u16::MIN..u16::MAX,
-            w in u16::MIN..u16::MAX,
-            h in u16::MIN..u16::MAX,
-        ) {
-            let bsp = Bsp(d, a, b);
-            assert_eq!(
-                Content::layout(&bsp, [x, y, w, h]),
-                Render::layout(&bsp, [x, y, w, h]),
-            );
-        }
-    }
-
-}
+#[cfg(test)] mod test;

output/src/ops.rs

@@ -1,9 +1,10 @@
+//mod reduce;    pub use self::reduce::*;
 mod align;     pub use self::align::*;
 mod bsp;       pub use self::bsp::*;
-mod cond;      pub use self::cond::*;
+mod either;    pub use self::either::*;
 mod map;       pub use self::map::*;
 mod memo;      pub use self::memo::*;
 mod stack;     pub use self::stack::*;
-//mod reduce;    pub use self::reduce::*;
 mod thunk;     pub use self::thunk::*;
 mod transform; pub use self::transform::*;
+mod when;      pub use self::when::*;

output/src/ops/align.rs

@@ -42,7 +42,7 @@ from_dsl!(@a: Align<A>: |state, iter|if let Some(Token { value: Value::Key(key),
         "align/n"|"align/s"|"align/e"|"align/w"|
         "align/nw"|"align/sw"|"align/ne"|"align/se" => {
             let _ = iter.next().unwrap();
-            let content = state.take_or_fail(&mut iter.clone(), "expected content")?;
+            let content = state.take_or_fail(&mut iter.clone(), ||"expected content")?;
             return Ok(Some(match key {
                 "align/c"  => Self::c(content),
                 "align/x"  => Self::x(content),

output/src/ops/bsp.rs

@@ -21,35 +21,29 @@ impl<E: Output, A: Content<E>, B: Content<E>> Content<E> for Bsp<A, B> {
     }
 }
 #[cfg(feature = "dsl")]
-from_dsl!(@ab: Bsp<A, B>: |state, iter|Ok(if let Some(Token {
-    value: Value::Key("bsp/n"|"bsp/s"|"bsp/e"|"bsp/w"|"bsp/a"|"bsp/b"),
-    ..
-}) = iter.peek() {
-    let base = iter.clone();
-    return Ok(Some(match iter.next() {
-        Some(Token { value: Value::Key("bsp/n"), .. }) =>
-            Self::n(state.take_or_fail(iter, "expected content 1")?,
-                    state.take_or_fail(iter, "expected content 2")?),
-        Some(Token { value: Value::Key("bsp/s"), .. }) =>
-            Self::s(state.take_or_fail(iter, "expected content 1")?,
-                    state.take_or_fail(iter, "expected content 2")?),
-        Some(Token { value: Value::Key("bsp/e"), .. }) =>
-            Self::e(state.take_or_fail(iter, "expected content 1")?,
-                    state.take_or_fail(iter, "expected content 2")?),
-        Some(Token { value: Value::Key("bsp/w"), .. }) =>
-            Self::w(state.take_or_fail(iter, "expected content 1")?,
-                    state.take_or_fail(iter, "expected content 2")?),
-        Some(Token { value: Value::Key("bsp/a"), .. }) =>
-            Self::a(state.take_or_fail(iter, "expected content 1")?,
-                    state.take_or_fail(iter, "expected content 2")?),
-        Some(Token { value: Value::Key("bsp/b"), .. }) =>
-            Self::b(state.take_or_fail(iter, "expected content 1")?,
-                    state.take_or_fail(iter, "expected content 2")?),
-        _ => unreachable!(),
-    }))
-} else {
-    None
-}));
+impl<State: Dsl<A> + Dsl<B> + std::fmt::Debug, A, B> Namespace<State> for Bsp<A, B> {
+    fn take_from <'source> (state: &State, words: &mut TokenIter<'source>) -> Perhaps<Self> {
+        Ok(if let Some(Token {
+            value: Value::Key("bsp/n"|"bsp/s"|"bsp/e"|"bsp/w"|"bsp/a"|"bsp/b"),
+            ..
+        }) = words.peek() {
+            let base = words.clone();
+            let a: A = state.take_or_fail(words, ||"expected content 1")?;
+            let b: B = state.take_or_fail(words, ||"expected content 2")?;
+            return Ok(Some(match words.next() {
+                Some(Token { value: Value::Key("bsp/n"), .. }) => Self::n(a, b),
+                Some(Token { value: Value::Key("bsp/s"), .. }) => Self::s(a, b),
+                Some(Token { value: Value::Key("bsp/e"), .. }) => Self::e(a, b),
+                Some(Token { value: Value::Key("bsp/w"), .. }) => Self::w(a, b),
+                Some(Token { value: Value::Key("bsp/a"), .. }) => Self::a(a, b),
+                Some(Token { value: Value::Key("bsp/b"), .. }) => Self::b(a, b),
+                _ => unreachable!(),
+            }))
+        } else {
+            None
+        })
+    }
+}
 impl<A, B> Bsp<A, B> {
     #[inline] pub const fn n (a: A, b: B) -> Self { Self(North, a, b) }
     #[inline] pub const fn s (a: A, b: B) -> Self { Self(South, a, b) }

output/src/ops/cond.rs

@@ -1,85 +0,0 @@
-use crate::*;
-
-/// Show an item only when a condition is true.
-pub struct When<A>(pub bool, pub A);
-impl<A> When<A> {
-    /// Create a binary condition.
-    pub const fn new (c: bool, a: A) -> Self {
-        Self(c, a)
-    }
-}
-
-/// Show one item if a condition is true and another if the condition is false
-pub struct Either<A, B>(pub bool, pub A, pub B);
-impl<A, B> Either<A, B> {
-    /// Create a ternary condition.
-    pub const fn new (c: bool, a: A, b: B) -> Self {
-        Self(c, a, b)
-    }
-}
-#[cfg(feature = "dsl")]
-impl<A, T: Dsl<bool> + Dsl<A>> Namespace<T> for When<A> {
-    fn take_from <'source> (
-        state: &T,
-        token: &mut TokenIter<'source>
-    ) -> Perhaps<Self> {
-        Ok(if let Some(Token {
-            value: Value::Key("when"),
-            ..
-        }) = token.peek() {
-            let base = token.clone();
-            return Ok(Some(Self(
-                state.take_or_fail(token, "cond: no condition")?,
-                state.take_or_fail(token, "cond: no content")?,
-            )))
-        } else {
-            None
-        })
-    }
-}
-impl<E: Output, A: Render<E>> Content<E> for When<A> {
-    fn layout (&self, to: E::Area) -> E::Area {
-        let Self(cond, item) = self;
-        let mut area = E::Area::zero();
-        if *cond {
-            let item_area = item.layout(to);
-            area[0] = item_area.x();
-            area[1] = item_area.y();
-            area[2] = item_area.w();
-            area[3] = item_area.h();
-        }
-        area.into()
-    }
-    fn render (&self, to: &mut E) {
-        let Self(cond, item) = self;
-        if *cond { item.render(to) }
-    }
-}
-#[cfg(feature = "dsl")]
-impl<A, B, T: Dsl<bool> + Dsl<A> + Dsl<B>> Namespace<T> for Either<A, B> {
-    fn take_from <'source> (
-        state: &T,
-        token: &mut TokenIter<'source>
-    ) -> Perhaps<Self> {
-        if let Some(Token { value: Value::Key("either"), .. }) = token.peek() {
-            let base = token.clone();
-            let _ = token.next().unwrap();
-            return Ok(Some(Self(
-                state.take_or_fail(token, "either: no condition")?,
-                state.take_or_fail(token, "either: no content 1")?,
-                state.take_or_fail(token, "either: no content 2")?,
-            )))
-        }
-        Ok(None)
-    }
-}
-impl<E: Output, A: Render<E>, B: Render<E>> Content<E> for Either<A, B> {
-    fn layout (&self, to: E::Area) -> E::Area {
-        let Self(cond, a, b) = self;
-        if *cond { a.layout(to) } else { b.layout(to) }
-    }
-    fn render (&self, to: &mut E) {
-        let Self(cond, a, b) = self;
-        if *cond { a.render(to) } else { b.render(to) }
-    }
-}

output/src/ops/either.rs

@@ -0,0 +1,38 @@
+use crate::*;
+
+/// Show one item if a condition is true and another if the condition is false
+pub struct Either<A, B>(pub bool, pub A, pub B);
+impl<A, B> Either<A, B> {
+    /// Create a ternary condition.
+    pub const fn new (c: bool, a: A, b: B) -> Self {
+        Self(c, a, b)
+    }
+}
+#[cfg(feature = "dsl")]
+impl<A, B, T: Dsl<bool> + Dsl<A> + Dsl<B>> Namespace<T> for Either<A, B> {
+    fn take_from <'source> (
+        state: &T,
+        token: &mut TokenIter<'source>
+    ) -> Perhaps<Self> {
+        if let Some(Token { value: Value::Key("either"), .. }) = token.peek() {
+            let base = token.clone();
+            let _ = token.next().unwrap();
+            return Ok(Some(Self(
+                state.take_or_fail(token, ||"either: no condition")?,
+                state.take_or_fail(token, ||"either: no content 1")?,
+                state.take_or_fail(token, ||"either: no content 2")?,
+            )))
+        }
+        Ok(None)
+    }
+}
+impl<E: Output, A: Render<E>, B: Render<E>> Content<E> for Either<A, B> {
+    fn layout (&self, to: E::Area) -> E::Area {
+        let Self(cond, a, b) = self;
+        if *cond { a.layout(to) } else { b.layout(to) }
+    }
+    fn render (&self, to: &mut E) {
+        let Self(cond, a, b) = self;
+        if *cond { a.render(to) } else { b.render(to) }
+    }
+}

output/src/ops/transform.rs

@@ -41,11 +41,11 @@ macro_rules! transform_xy {
                     let mut base = token.clone();
                     return Ok(Some(match token.next() {
                         Some(Token{value:Value::Key($x),..}) =>
-                            Self::x(state.take_or_fail(token, "x: no content")?),
+                            Self::x(state.take_or_fail(token, ||"x: no content")?),
                         Some(Token{value:Value::Key($y),..}) =>
-                            Self::y(state.take_or_fail(token, "y: no content")?),
+                            Self::y(state.take_or_fail(token, ||"y: no content")?),
                         Some(Token{value:Value::Key($xy),..}) =>
-                            Self::xy(state.take_or_fail(token, "xy: no content")?),
+                            Self::xy(state.take_or_fail(token, ||"xy: no content")?),
                         _ => unreachable!()
                     }))
                 }
@@ -87,17 +87,17 @@ macro_rules! transform_xy_unit {
                     let mut base = token.clone();
                     Some(match token.next() {
                         Some(Token { value: Value::Key($x), .. }) => Self::x(
-                            state.take_or_fail(token, "x: no unit")?,
-                            state.take_or_fail(token, "x: no content")?,
+                            state.take_or_fail(token, ||"x: no unit")?,
+                            state.take_or_fail(token, ||"x: no content")?,
                         ),
                         Some(Token { value: Value::Key($y), .. }) => Self::y(
-                            state.take_or_fail(token, "y: no unit")?,
-                            state.take_or_fail(token, "y: no content")?,
+                            state.take_or_fail(token, ||"y: no unit")?,
+                            state.take_or_fail(token, ||"y: no content")?,
                         ),
                         Some(Token { value: Value::Key($x), .. }) => Self::xy(
-                            state.take_or_fail(token, "xy: no unit x")?,
-                            state.take_or_fail(token, "xy: no unit y")?,
-                            state.take_or_fail(token, "xy: no content")?
+                            state.take_or_fail(token, ||"xy: no unit x")?,
+                            state.take_or_fail(token, ||"xy: no unit y")?,
+                            state.take_or_fail(token, ||"xy: no content")?
                         ),
                         _ => unreachable!(),
                     })

output/src/ops/when.rs

@@ -0,0 +1,48 @@
+use crate::*;
+
+/// Show an item only when a condition is true.
+pub struct When<A>(pub bool, pub A);
+impl<A> When<A> {
+    /// Create a binary condition.
+    pub const fn new (c: bool, a: A) -> Self {
+        Self(c, a)
+    }
+}
+#[cfg(feature = "dsl")]
+impl<A, T: Dsl<bool> + Dsl<A>> Namespace<T> for When<A> {
+    fn take_from <'source> (
+        state: &T,
+        token: &mut TokenIter<'source>
+    ) -> Perhaps<Self> {
+        Ok(if let Some(Token {
+            value: Value::Key("when"),
+            ..
+        }) = token.peek() {
+            let base = token.clone();
+            return Ok(Some(Self(
+                state.take_or_fail(token, ||"cond: no condition")?,
+                state.take_or_fail(token, ||"cond: no content")?,
+            )))
+        } else {
+            None
+        })
+    }
+}
+impl<E: Output, A: Render<E>> Content<E> for When<A> {
+    fn layout (&self, to: E::Area) -> E::Area {
+        let Self(cond, item) = self;
+        let mut area = E::Area::zero();
+        if *cond {
+            let item_area = item.layout(to);
+            area[0] = item_area.x();
+            area[1] = item_area.y();
+            area[2] = item_area.w();
+            area[3] = item_area.h();
+        }
+        area.into()
+    }
+    fn render (&self, to: &mut E) {
+        let Self(cond, item) = self;
+        if *cond { item.render(to) }
+    }
+}

output/src/test.rs

@@ -0,0 +1,170 @@
+use crate::*;
+use proptest_derive::Arbitrary;
+use proptest::{prelude::*, option::of};
+
+proptest! {
+    #[test] fn proptest_direction (
+        d in prop_oneof![
+            Just(North), Just(South),
+            Just(East),  Just(West),
+            Just(Above), Just(Below)
+        ],
+        x in u16::MIN..u16::MAX,
+        y in u16::MIN..u16::MAX,
+        w in u16::MIN..u16::MAX,
+        h in u16::MIN..u16::MAX,
+        a in u16::MIN..u16::MAX,
+    ) {
+        let _ = d.split_fixed([x, y, w, h], a);
+    }
+}
+
+proptest! {
+    #[test] fn proptest_size (
+        x in u16::MIN..u16::MAX,
+        y in u16::MIN..u16::MAX,
+        a in u16::MIN..u16::MAX,
+        b in u16::MIN..u16::MAX,
+    ) {
+        let size = [x, y];
+        let _ = size.w();
+        let _ = size.h();
+        let _ = size.wh();
+        let _ = size.clip_w(a);
+        let _ = size.clip_h(b);
+        let _ = size.expect_min(a, b);
+        let _ = size.to_area_pos();
+        let _ = size.to_area_size();
+    }
+}
+
+proptest! {
+    #[test] fn proptest_area (
+        x in u16::MIN..u16::MAX,
+        y in u16::MIN..u16::MAX,
+        w in u16::MIN..u16::MAX,
+        h in u16::MIN..u16::MAX,
+        a in u16::MIN..u16::MAX,
+        b in u16::MIN..u16::MAX,
+    ) {
+        let _: [u16;4] = <[u16;4] as Area<u16>>::zero();
+        let _: [u16;4] = <[u16;4] as Area<u16>>::from_position([a, b]);
+        let _: [u16;4] = <[u16;4] as Area<u16>>::from_size([a, b]);
+        let area: [u16;4] = [x, y, w, h];
+        let _ = area.expect_min(a, b);
+        let _ = area.xy();
+        let _ = area.wh();
+        let _ = area.xywh();
+        let _ = area.clip_h(a);
+        let _ = area.clip_w(b);
+        let _ = area.clip([a, b]);
+        let _ = area.set_w(a);
+        let _ = area.set_h(b);
+        let _ = area.x2();
+        let _ = area.y2();
+        let _ = area.lrtb();
+        let _ = area.center();
+        let _ = area.center_x(a);
+        let _ = area.center_y(b);
+        let _ = area.center_xy([a, b]);
+        let _ = area.centered();
+    }
+}
+
+macro_rules! test_op_transform {
+    ($fn:ident, $Op:ident) => {
+        proptest! {
+            #[test] fn $fn (
+                op_x in of(u16::MIN..u16::MAX),
+                op_y in of(u16::MIN..u16::MAX),
+                content in "\\PC*",
+                x in u16::MIN..u16::MAX,
+                y in u16::MIN..u16::MAX,
+                w in u16::MIN..u16::MAX,
+                h in u16::MIN..u16::MAX,
+            ) {
+                if let Some(op) = match (op_x, op_y) {
+                    (Some(x), Some(y)) => Some($Op::xy(x, y, content)),
+                    (Some(x), None)    => Some($Op::x(x, content)),
+                    (Some(y), None)    => Some($Op::y(y, content)),
+                    _ => None
+                } {
+                    assert_eq!(Content::layout(&op, [x, y, w, h]),
+                               Render::layout(&op,  [x, y, w, h]));
+                }
+            }
+        }
+    }
+}
+
+test_op_transform!(proptest_op_fixed,   Fixed);
+test_op_transform!(proptest_op_min,     Min);
+test_op_transform!(proptest_op_max,     Max);
+test_op_transform!(proptest_op_push,    Push);
+test_op_transform!(proptest_op_pull,    Pull);
+test_op_transform!(proptest_op_shrink,  Shrink);
+test_op_transform!(proptest_op_expand,  Expand);
+test_op_transform!(proptest_op_margin,  Margin);
+test_op_transform!(proptest_op_padding, Padding);
+
+proptest! {
+    #[test] fn proptest_op_bsp (
+        d in prop_oneof![
+            Just(North), Just(South),
+            Just(East),  Just(West),
+            Just(Above), Just(Below)
+        ],
+        a in "\\PC*",
+        b in "\\PC*",
+        x in u16::MIN..u16::MAX,
+        y in u16::MIN..u16::MAX,
+        w in u16::MIN..u16::MAX,
+        h in u16::MIN..u16::MAX,
+    ) {
+        let bsp = Bsp(d, a, b);
+        assert_eq!(
+            Content::layout(&bsp, [x, y, w, h]),
+            Render::layout(&bsp, [x, y, w, h]),
+        );
+    }
+}
+
+#[test] fn test_stub_output () -> Usually<()> {
+    use crate::*;
+    struct TestOutput([u16;4]);
+    impl Output for TestOutput {
+        type Unit = u16;
+        type Size = [u16;2];
+        type Area = [u16;4];
+        fn area (&self) -> [u16;4] {
+            self.0
+        }
+        fn area_mut (&mut self) -> &mut [u16;4] {
+            &mut self.0
+        }
+        fn place (&mut self, _: [u16;4], _: &impl Render<TestOutput>) {
+            ()
+        }
+    }
+    impl Content<TestOutput> for String {
+        fn render (&self, to: &mut TestOutput) {
+            to.area_mut().set_w(self.len() as u16);
+        }
+    }
+    Ok(())
+}
+
+#[test] fn test_space () {
+    use crate::*;
+    assert_eq!(Area::center(&[10u16, 10, 20, 20]), [20, 20]);
+}
+
+#[test] fn test_iter_map () {
+    struct Foo;
+    impl<T: Output> Content<T> for Foo {}
+    fn make_map <T: Output, U: Content<T> + Send + Sync> (data: &Vec<U>) -> impl Content<T> {
+        Map::new(||data.iter(), |foo, index|{})
+    }
+    let data = vec![Foo, Foo, Foo];
+    //let map = make_map(&data);
+}

output/src/view.rs

@@ -1,54 +0,0 @@
-use crate::*;
-
-//#[cfg(feature = "dsl")]
-//#[macro_export] macro_rules! try_delegate {
-    //($s:ident, $dsl:expr, $T:ty) => {
-        //let value: Option<$T> = Dsl::take_from($s, $dsl)?;
-        //if let Some(value) = value {
-            //return Ok(Some(value.boxed()))
-        //}
-    //}
-//}
-
-//// Provides components to the view.
-//#[cfg(feature = "dsl")]
-//pub trait ViewContext<'state, E: Output + 'state>:
-    //Namespace<bool> + Namespace<usize> + Namespace<E::Unit> + Send + Sync
-//{
-    //fn get_content_sym <'source: 'state> (&'state self, iter: &mut TokenIter<'source>)
-        //-> Perhaps<RenderBox<'state, E>>;
-    //fn get_content_exp <'source: 'state> (&'state self, iter: &mut TokenIter<'source>)
-        //-> Perhaps<RenderBox<'state, E>>
-    //{
-        //try_delegate!(self, iter, When::<RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Either::<RenderBox<'state, E>, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Align::<RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Bsp::<RenderBox<'state, E>, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Fill::<RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Fixed::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Min::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Max::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Shrink::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Expand::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Push::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Pull::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Margin::<_, RenderBox<'state, E>>);
-        //try_delegate!(self, iter, Padding::<_, RenderBox<'state, E>>);
-        //Ok(None)
-    //}
-//}
-
-//#[cfg(feature = "dsl")]
-//impl<'context, O: Output + 'context, T: ViewContext<'context, O>> Namespace<T> for RenderBox<'context, O> {
-    //fn take_from <'state, 'source: 'state> (state: &'state T, token: &mut TokenIter<'source>)
-        //-> Perhaps<RenderBox<'context, O>>
-    //{
-        //Ok(if let Some(content) = state.get_content_sym(token)? {
-            //Some(content)
-        //} else if let Some(content) = state.get_content_exp(token)? {
-            //Some(content)
-        //} else {
-            //None
-        //})
-    //}
-//}

proc/src/proc_view.rs

@@ -42,50 +42,53 @@ impl Parse for ViewImpl {
 impl ToTokens for ViewDef {
     fn to_tokens (&self, out: &mut TokenStream2) {
         let Self(ViewMeta { output }, ViewImpl { block, exposed }) = self;
-        let view = &block.self_ty;
-        let builtins = builtins().iter().map(|ty|write_quote(quote! {
-            if let Some(value) = Namespace::<#ty>::take_from(state, &mut exp.clone())? {
-                return Ok(Some(value.boxed()))
-            }
-        })).collect::<Vec<_>>();
-        let mut available = vec![];
-        let exposed: Vec<_> = exposed.iter().map(|(key, value)|{
-            available.push(key.clone());
-            write_quote(quote! { #key => Some(#view::#value(state).boxed()), })
-        }).collect();
-        let available: String = available.join(", ");
-        let error_msg = LitStr::new(
-            &format!("expected Sym(content), got: {{token:?}}, available: {available}"),
-            Span::call_site()
-        );
+        let self_ty = &block.self_ty;
+        let builtins: Vec<_> = builtins_with_types()
+            .iter()
+            .map(|ty|write_quote(quote! {
+                let value: Option<#ty> = Dsl::take(state, &mut exp.clone())?;
+                if let Some(value) = value {
+                    return Ok(Some(value.boxed()))
+                }
+            }))
+        .collect();
+        let exposed: Vec<_> = exposed
+            .iter()
+            .map(|(key, value)|write_quote(quote! {
+                #key => Some(#self_ty::#value(state).boxed()),
+            })).collect();
         write_quote_to(out, quote! {
             #block
             /// Generated by [tengri_proc].
             ///
-            /// Delegates the rendering of [#view] to the [#view::view} method,
+            /// Delegates the rendering of [#self_ty] to the [#self_ty::view} method,
             /// which you will need to implement, e.g. passing a [TokenIter]
             /// containing a layout and keybindings config from user dirs.
-            impl ::tengri::output::Content<#output> for #view {
+            impl ::tengri::output::Content<#output> for #self_ty {
                 fn content (&self) -> impl Render<#output> {
-                    self.view()
+                    #self_ty::view(self)
                 }
             }
             /// Generated by [tengri_proc].
             ///
-            /// Gives [#view] the ability to construct the [Render]able
+            /// Gives [#self_ty] the ability to construct the [Render]able
             /// which might corresponds to a given [TokenStream],
-            /// while taking [#view]'s state into consideration.
-            impl ::tengri::dsl::Namespace<#view> for Box<dyn Render<#output>> {
+            /// while taking [#self_ty]'s state into consideration.
+            impl ::tengri::dsl::Namespace<#self_ty> for Box<dyn Render<#output> + '_> {
                 fn take_from <'source> (
-                    state: &#view,
+                    state: &#self_ty,
                     words: &mut ::tengri::dsl::TokenIter<'source>
                 ) -> Perhaps<Self> {
                     Ok(if let Some(::tengri::dsl::Token { value, .. }) = words.peek() {
                         match value {
+                            // Expressions are handled by built-in functions
+                            // that operate over constants and symbols.
                             ::tengri::dsl::Value::Exp(_, exp) => {
-                                //#(#builtins)*
+                                #(#builtins)*
                                 None
                             },
+                            // Symbols are handled by user-provided functions
+                            // that take no parameters but `&self`.
                             ::tengri::dsl::Value::Sym(sym) => match sym {
                                 #(#exposed)*
                                 _ => None
@@ -101,21 +104,21 @@ impl ToTokens for ViewDef {
     }
 }
 
-fn builtins () -> [TokenStream2;14] {
+fn builtins_with_types () -> [TokenStream2;14] {
     [
-        quote! { When::<_>       },
-        quote! { Either::<_, _>  },
-        quote! { Align::<_>      },
-        quote! { Bsp::<_, _>     },
-        quote! { Fill::<_>       },
-        quote! { Fixed::<_, _>   },
-        quote! { Min::<_, _>     },
-        quote! { Max::<_, _>     },
-        quote! { Shrink::<_, _>  },
-        quote! { Expand::<_, _>  },
-        quote! { Push::<_, _>    },
-        quote! { Pull::<_, _>    },
-        quote! { Margin::<_, _>  },
-        quote! { Padding::<_, _> },
+        quote! { When<      Box<dyn Render<_> + '_>                         > },
+        quote! { Either<    Box<dyn Render<_> + '_>, Box<dyn Render<_> + '_>> },
+        quote! { Align<     Box<dyn Render<_> + '_>                         > },
+        quote! { Bsp<       Box<dyn Render<_> + '_>, Box<dyn Render<_> + '_>> },
+        quote! { Fill<      Box<dyn Render<_> + '_>                         > },
+        quote! { Fixed<_,   Box<dyn Render<_> + '_>                         > },
+        quote! { Min<_,     Box<dyn Render<_> + '_>                         > },
+        quote! { Max<_,     Box<dyn Render<_> + '_>                         > },
+        quote! { Shrink<_,  Box<dyn Render<_> + '_>                         > },
+        quote! { Expand<_,  Box<dyn Render<_> + '_>                         > },
+        quote! { Push<_,    Box<dyn Render<_> + '_>                         > },
+        quote! { Pull<_,    Box<dyn Render<_> + '_>                         > },
+        quote! { Margin<_,  Box<dyn Render<_> + '_>                         > },
+        quote! { Padding<_, Box<dyn Render<_> + '_>                         > },
     ]
 }