Reflection for castables

13 files changed, 93 insertions, 58 deletions

diff --git a/library/src/layout/align.rs b/library/src/layout/align.rs
index 4fae3c3c..f00aeaf2 100644
--- a/library/src/layout/align.rs
+++ b/library/src/layout/align.rs
@@ -1,6 +1,8 @@
 use crate::prelude::*;
 
 /// Align content horizontally and vertically.
+///
+/// Tags: layout.
 #[func]
 #[capable]
 #[derive(Debug, Hash)]
diff --git a/library/src/layout/columns.rs b/library/src/layout/columns.rs
index 0e29bc00..3bbf56e4 100644
--- a/library/src/layout/columns.rs
+++ b/library/src/layout/columns.rs
@@ -2,6 +2,8 @@ use crate::prelude::*;
 use crate::text::TextNode;
 
 /// Separate a region into multiple equally sized columns.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout)]
 #[derive(Debug, Hash)]
@@ -103,6 +105,8 @@ impl Layout for ColumnsNode {
 }
 
 /// A column break.
+///
+/// Tags: layout.
 #[func]
 #[capable(Behave)]
 #[derive(Debug, Hash)]
diff --git a/library/src/layout/container.rs b/library/src/layout/container.rs
index 85257715..d451bccf 100644
--- a/library/src/layout/container.rs
+++ b/library/src/layout/container.rs
@@ -2,6 +2,8 @@ use super::VNode;
 use crate::prelude::*;
 
 /// An inline-level container that sizes content.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout, Inline)]
 #[derive(Debug, Hash)]
@@ -62,6 +64,8 @@ impl Layout for BoxNode {
 impl Inline for BoxNode {}
 
 /// A block-level container that places content into a separate flow.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout)]
 #[derive(Debug, Hash)]
@@ -70,10 +74,10 @@ pub struct BlockNode(pub Content);
 #[node]
 impl BlockNode {
     /// The spacing between the previous and this block.
-    #[property(skip)]
+    #[property(reflect, skip)]
     pub const ABOVE: VNode = VNode::block_spacing(Em::new(1.2).into());
     /// The spacing between this and the following block.
-    #[property(skip)]
+    #[property(reflect, skip)]
     pub const BELOW: VNode = VNode::block_spacing(Em::new(1.2).into());
     /// Whether this block must stick to the following one.
     #[property(skip)]
diff --git a/library/src/layout/grid.rs b/library/src/layout/grid.rs
index 2a6bd4ff..e70210c0 100644
--- a/library/src/layout/grid.rs
+++ b/library/src/layout/grid.rs
@@ -3,6 +3,8 @@ use crate::prelude::*;
 use super::Spacing;
 
 /// Arrange content in a grid.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout)]
 #[derive(Debug, Hash)]
@@ -85,17 +87,9 @@ pub struct TrackSizings(pub Vec<TrackSizing>);
 
 castable! {
     TrackSizings,
-    Expected: "integer, auto, relative length, fraction, or array of the latter three",
-    Value::Auto => Self(vec![TrackSizing::Auto]),
-    Value::Length(v) => Self(vec![TrackSizing::Relative(v.into())]),
-    Value::Ratio(v) => Self(vec![TrackSizing::Relative(v.into())]),
-    Value::Relative(v) => Self(vec![TrackSizing::Relative(v)]),
-    Value::Fraction(v) => Self(vec![TrackSizing::Fractional(v)]),
-    Value::Int(v) => Self(vec![
-        TrackSizing::Auto;
-        Value::Int(v).cast::<NonZeroUsize>()?.get()
-    ]),
-    Value::Array(values) => Self(values
+    sizing: TrackSizing => Self(vec![sizing]),
+    count: NonZeroUsize => Self(vec![TrackSizing::Auto; count.get()]),
+    values: Array => Self(values
         .into_iter()
         .filter_map(|v| v.cast().ok())
         .collect()),
@@ -103,12 +97,9 @@ castable! {
 
 castable! {
     TrackSizing,
-    Expected: "auto, relative length, or fraction",
-    Value::Auto => Self::Auto,
-    Value::Length(v) => Self::Relative(v.into()),
-    Value::Ratio(v) => Self::Relative(v.into()),
-    Value::Relative(v) => Self::Relative(v),
-    Value::Fraction(v) => Self::Fractional(v),
+    _: AutoValue => Self::Auto,
+    v: Rel<Length> => Self::Relative(v),
+    v: Fr => Self::Fractional(v),
 }
 
 /// Performs grid layout.
diff --git a/library/src/layout/hide.rs b/library/src/layout/hide.rs
index 1318b7ed..4e70dca9 100644
--- a/library/src/layout/hide.rs
+++ b/library/src/layout/hide.rs
@@ -1,6 +1,8 @@
 use crate::prelude::*;
 
 /// Hide content without affecting layout.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout, Inline)]
 #[derive(Debug, Hash)]
diff --git a/library/src/layout/pad.rs b/library/src/layout/pad.rs
index 9c44919d..9d882ba4 100644
--- a/library/src/layout/pad.rs
+++ b/library/src/layout/pad.rs
@@ -1,6 +1,8 @@
 use crate::prelude::*;
 
 /// Pad content at the sides.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout)]
 #[derive(Debug, Hash)]
diff --git a/library/src/layout/page.rs b/library/src/layout/page.rs
index 5a23b27b..fe83137e 100644
--- a/library/src/layout/page.rs
+++ b/library/src/layout/page.rs
@@ -5,6 +5,8 @@ use crate::prelude::*;
 use crate::text::TextNode;
 
 /// Layouts its child onto one or multiple pages.
+///
+/// Tags: layout.
 #[func]
 #[capable]
 #[derive(Clone, Hash)]
@@ -12,6 +14,9 @@ pub struct PageNode(pub Content);
 
 #[node]
 impl PageNode {
+    /// The paper size.
+    #[property(reflect, skip, shorthand)]
+    pub const PAPER: Paper = Paper::A4;
     /// The unflipped width of the page.
     #[property(resolve)]
     pub const WIDTH: Smart<Length> = Smart::Custom(Paper::A4.width().into());
@@ -145,6 +150,8 @@ impl Debug for PageNode {
 }
 
 /// A page break.
+///
+/// Tags: layout.
 #[func]
 #[capable]
 #[derive(Debug, Copy, Clone, Hash)]
@@ -187,7 +194,10 @@ impl Marginal {
 
 impl Cast<Spanned<Value>> for Marginal {
     fn is(value: &Spanned<Value>) -> bool {
-        matches!(&value.v, Value::Content(_) | Value::Func(_))
+        matches!(
+            &value.v,
+            Value::None | Value::Str(_) | Value::Content(_) | Value::Func(_)
+        )
     }
 
     fn cast(value: Spanned<Value>) -> StrResult<Self> {
@@ -196,43 +206,51 @@ impl Cast<Spanned<Value>> for Marginal {
             Value::Str(v) => Ok(Self::Content(TextNode::packed(v))),
             Value::Content(v) => Ok(Self::Content(v)),
             Value::Func(v) => Ok(Self::Func(v, value.span)),
-            v => Err(format_eco!(
-                "expected none, content or function, found {}",
-                v.type_name(),
-            )),
+            v => Self::error(v),
         }
     }
+
+    fn describe() -> CastInfo {
+        CastInfo::Union(vec![
+            CastInfo::Type("none"),
+            CastInfo::Type("content"),
+            CastInfo::Type("function"),
+        ])
+    }
 }
 
 /// Specification of a paper.
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, Hash)]
 pub struct Paper {
     /// The width of the paper in millimeters.
-    width: f64,
+    width: Scalar,
     /// The height of the paper in millimeters.
-    height: f64,
+    height: Scalar,
 }
 
 impl Paper {
     /// The width of the paper.
     pub fn width(self) -> Abs {
-        Abs::mm(self.width)
+        Abs::mm(self.width.0)
     }
 
     /// The height of the paper.
     pub fn height(self) -> Abs {
-        Abs::mm(self.height)
+        Abs::mm(self.height.0)
     }
 }
 
 /// Defines paper constants and a paper parsing implementation.
 macro_rules! papers {
-    ($(($var:ident: $width:expr, $height: expr, $($pats:tt)*))*) => {
+    ($(($var:ident: $width:expr, $height: expr, $pat:literal))*) => {
         /// Predefined papers.
         ///
         /// Each paper is parsable from its name in kebab-case.
         impl Paper {
-            $(pub const $var: Self = Self { width: $width, height: $height };)*
+            $(pub const $var: Self = Self {
+                width: Scalar($width),
+                height: Scalar($height),
+            };)*
         }
 
         impl FromStr for Paper {
@@ -240,18 +258,17 @@ macro_rules! papers {
 
             fn from_str(name: &str) -> Result<Self, Self::Err> {
                 match name.to_lowercase().as_str() {
-                    $($($pats)* => Ok(Self::$var),)*
+                    $($pat => Ok(Self::$var),)*
                     _ => Err("invalid paper name"),
                 }
             }
         }
-    };
-}
 
-castable! {
-    Paper,
-    Expected: "string",
-    Value::Str(string) => Self::from_str(&string)?,
+        castable! {
+            Paper,
+            $($pat => Self::$var,)*
+        }
+    };
 }
 
 // All paper sizes in mm.
diff --git a/library/src/layout/par.rs b/library/src/layout/par.rs
index 925eea54..eed0dbb1 100644
--- a/library/src/layout/par.rs
+++ b/library/src/layout/par.rs
@@ -12,6 +12,8 @@ use crate::text::{
 };
 
 /// Arrange text, spacing and inline-level nodes into a paragraph.
+///
+/// Tags: layout.
 #[func]
 #[capable]
 #[derive(Hash)]
@@ -109,9 +111,8 @@ pub struct HorizontalAlign(pub GenAlign);
 
 castable! {
     HorizontalAlign,
-    Expected: "alignment",
-    @align: GenAlign => match align.axis() {
-        Axis::X => Self(*align),
+    align: GenAlign => match align.axis() {
+        Axis::X => Self(align),
         Axis::Y => Err("must be horizontal")?,
     },
 }
@@ -135,15 +136,15 @@ pub enum Linebreaks {
 
 castable! {
     Linebreaks,
-    Expected: "string",
-    Value::Str(string) => match string.as_str() {
-        "simple" => Self::Simple,
-        "optimized" => Self::Optimized,
-        _ => Err(r#"expected "simple" or "optimized""#)?,
-    },
+    /// Determine the linebreaks in a simple first-fit style.
+    "simple" => Self::Simple,
+    /// Optimize the linebreaks for the whole paragraph.
+    "optimized" => Self::Optimized,
 }
 
 /// A paragraph break.
+///
+/// Tags: layout.
 #[func]
 #[capable(Unlabellable)]
 #[derive(Debug, Hash)]
diff --git a/library/src/layout/place.rs b/library/src/layout/place.rs
index 4c9c0a46..c3fcd0d5 100644
--- a/library/src/layout/place.rs
+++ b/library/src/layout/place.rs
@@ -1,6 +1,8 @@
 use crate::prelude::*;
 
 /// Place content at an absolute position.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout, Behave)]
 #[derive(Debug, Hash)]
diff --git a/library/src/layout/repeat.rs b/library/src/layout/repeat.rs
index 196f19de..a47dbb3e 100644
--- a/library/src/layout/repeat.rs
+++ b/library/src/layout/repeat.rs
@@ -1,6 +1,8 @@
 use crate::prelude::*;
 
 /// Repeats content to fill a line.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout, Inline)]
 #[derive(Debug, Hash)]
diff --git a/library/src/layout/spacing.rs b/library/src/layout/spacing.rs
index 91e45b03..e961c0cf 100644
--- a/library/src/layout/spacing.rs
+++ b/library/src/layout/spacing.rs
@@ -3,6 +3,8 @@ use std::cmp::Ordering;
 use crate::prelude::*;
 
 /// Horizontal spacing.
+///
+/// Tags: layout.
 #[func]
 #[capable(Behave)]
 #[derive(Debug, Copy, Clone, Hash)]
@@ -52,6 +54,8 @@ impl Behave for HNode {
 }
 
 /// Vertical spacing.
+///
+/// Tags: layout.
 #[func]
 #[capable(Behave)]
 #[derive(Debug, Copy, Clone, Hash, PartialEq, PartialOrd)]
@@ -119,6 +123,11 @@ impl Behave for VNode {
     }
 }
 
+castable! {
+    VNode,
+    spacing: Spacing => VNode::block_around(spacing),
+}
+
 /// Kinds of spacing.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub enum Spacing {
@@ -160,9 +169,6 @@ impl PartialOrd for Spacing {
 
 castable! {
     Spacing,
-    Expected: "relative length or fraction",
-    Value::Length(v) => Self::Relative(v.into()),
-    Value::Ratio(v) => Self::Relative(v.into()),
-    Value::Relative(v) => Self::Relative(v),
-    Value::Fraction(v) => Self::Fractional(v),
+    v: Rel<Length> => Self::Relative(v),
+    v: Fr => Self::Fractional(v),
 }
diff --git a/library/src/layout/stack.rs b/library/src/layout/stack.rs
index 1e956669..111e3433 100644
--- a/library/src/layout/stack.rs
+++ b/library/src/layout/stack.rs
@@ -4,6 +4,8 @@ use super::{AlignNode, Spacing};
 use crate::prelude::*;
 
 /// Arrange content and spacing along an axis.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout)]
 #[derive(Debug, Hash)]
@@ -81,12 +83,8 @@ impl Debug for StackChild {
 
 castable! {
     StackChild,
-    Expected: "relative length, fraction, or content",
-    Value::Length(v) => Self::Spacing(Spacing::Relative(v.into())),
-    Value::Ratio(v) => Self::Spacing(Spacing::Relative(v.into())),
-    Value::Relative(v) => Self::Spacing(Spacing::Relative(v)),
-    Value::Fraction(v) => Self::Spacing(Spacing::Fractional(v)),
-    Value::Content(v) => Self::Block(v),
+    spacing: Spacing => Self::Spacing(spacing),
+    content: Content => Self::Block(content),
 }
 
 /// Performs stack layout.
diff --git a/library/src/layout/transform.rs b/library/src/layout/transform.rs
index 35b6709a..f1a89d4c 100644
--- a/library/src/layout/transform.rs
+++ b/library/src/layout/transform.rs
@@ -3,6 +3,8 @@ use typst::geom::Transform;
 use crate::prelude::*;
 
 /// Move content without affecting layout.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout, Inline)]
 #[derive(Debug, Hash)]
@@ -46,6 +48,8 @@ impl Layout for MoveNode {
 impl Inline for MoveNode {}
 
 /// Transform content without affecting layout.
+///
+/// Tags: layout.
 #[func]
 #[capable(Layout, Inline)]
 #[derive(Debug, Hash)]