Castable optional and smart values

15 files changed, 215 insertions, 103 deletions

diff --git a/src/eval/value.rs b/src/eval/value.rs
index e224438a..dec5c6c0 100644
--- a/src/eval/value.rs
+++ b/src/eval/value.rs
@@ -252,43 +252,6 @@ pub trait Cast<V>: Sized {
     fn cast(value: V) -> StrResult<Self>;
 }
 
-impl Cast<Value> for Value {
-    fn is(_: &Value) -> bool {
-        true
-    }
-
-    fn cast(value: Value) -> StrResult<Self> {
-        Ok(value)
-    }
-}
-
-impl<T> Cast<Spanned<Value>> for T
-where
-    T: Cast<Value>,
-{
-    fn is(value: &Spanned<Value>) -> bool {
-        T::is(&value.v)
-    }
-
-    fn cast(value: Spanned<Value>) -> StrResult<Self> {
-        T::cast(value.v)
-    }
-}
-
-impl<T> Cast<Spanned<Value>> for Spanned<T>
-where
-    T: Cast<Value>,
-{
-    fn is(value: &Spanned<Value>) -> bool {
-        T::is(&value.v)
-    }
-
-    fn cast(value: Spanned<Value>) -> StrResult<Self> {
-        let span = value.span;
-        T::cast(value.v).map(|t| Spanned::new(t, span))
-    }
-}
-
 /// Implement traits for primitives.
 macro_rules! primitive {
     (
@@ -400,6 +363,113 @@ primitive! { Dict: "dictionary", Dict }
 primitive! { Template: "template", Template }
 primitive! { Function: "function", Func }
 
+impl Cast<Value> for Value {
+    fn is(_: &Value) -> bool {
+        true
+    }
+
+    fn cast(value: Value) -> StrResult<Self> {
+        Ok(value)
+    }
+}
+
+impl<T> Cast<Spanned<Value>> for T
+where
+    T: Cast<Value>,
+{
+    fn is(value: &Spanned<Value>) -> bool {
+        T::is(&value.v)
+    }
+
+    fn cast(value: Spanned<Value>) -> StrResult<Self> {
+        T::cast(value.v)
+    }
+}
+
+impl<T> Cast<Spanned<Value>> for Spanned<T>
+where
+    T: Cast<Value>,
+{
+    fn is(value: &Spanned<Value>) -> bool {
+        T::is(&value.v)
+    }
+
+    fn cast(value: Spanned<Value>) -> StrResult<Self> {
+        let span = value.span;
+        T::cast(value.v).map(|t| Spanned::new(t, span))
+    }
+}
+
+/// A value that can be automatically determined.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+pub enum Smart<T> {
+    /// The value should be determined smartly based on the
+    /// circumstances.
+    Auto,
+    /// A forced, specific value.
+    Custom(T),
+}
+
+impl<T> Smart<T> {
+    /// Returns the contained custom value or a provided default value.
+    pub fn unwrap_or(self, default: T) -> T {
+        match self {
+            Self::Auto => default,
+            Self::Custom(x) => x,
+        }
+    }
+}
+
+impl<T> Default for Smart<T> {
+    fn default() -> Self {
+        Self::Auto
+    }
+}
+
+impl<T> Cast<Value> for Option<T>
+where
+    T: Cast<Value>,
+{
+    fn is(value: &Value) -> bool {
+        matches!(value, Value::None) || T::is(value)
+    }
+
+    fn cast(value: Value) -> StrResult<Self> {
+        match value {
+            Value::None => Ok(None),
+            v => T::cast(v).map(Some).map_err(|msg| with_alternative(msg, "none")),
+        }
+    }
+}
+
+impl<T> Cast<Value> for Smart<T>
+where
+    T: Cast<Value>,
+{
+    fn is(value: &Value) -> bool {
+        matches!(value, Value::Auto) || T::is(value)
+    }
+
+    fn cast(value: Value) -> StrResult<Self> {
+        match value {
+            Value::Auto => Ok(Self::Auto),
+            v => T::cast(v)
+                .map(Self::Custom)
+                .map_err(|msg| with_alternative(msg, "auto")),
+        }
+    }
+}
+
+/// Transform `expected X, found Y` into `expected X or A, found Y`.
+fn with_alternative(msg: String, alt: &str) -> String {
+    let mut parts = msg.split(", found ");
+    if let (Some(a), Some(b)) = (parts.next(), parts.next()) {
+        format!("{} or {}, found {}", a, alt, b)
+    } else {
+        msg
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/src/library/deco.rs b/src/library/deco.rs
index 1f8c051f..cb065689 100644
--- a/src/library/deco.rs
+++ b/src/library/deco.rs
@@ -17,7 +17,7 @@ pub fn overline(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 }
 
 fn line_impl(args: &mut Args, kind: LineKind) -> TypResult<Value> {
-    let stroke = args.named("stroke")?.or_else(|| args.find()).map(Paint::Solid);
+    let stroke = args.named("stroke")?.or_else(|| args.find());
     let thickness = args.named::<Linear>("thickness")?.or_else(|| args.find());
     let offset = args.named("offset")?;
     let extent = args.named("extent")?.unwrap_or_default();
diff --git a/src/library/mod.rs b/src/library/mod.rs
index 7b8acf9e..6260e6fc 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -26,7 +26,7 @@ mod prelude {
     pub use std::rc::Rc;
 
     pub use crate::diag::{At, TypResult};
-    pub use crate::eval::{Args, EvalContext, Template, Value};
+    pub use crate::eval::{Args, EvalContext, Smart, Template, Value};
     pub use crate::frame::*;
     pub use crate::geom::*;
     pub use crate::layout::*;
@@ -144,3 +144,9 @@ dynamic! {
     FontFamily: "font family",
     Value::Str(string) => Self::Named(string.to_lowercase()),
 }
+
+castable! {
+    Paint,
+    Expected: "color",
+    Value::Color(color) => Paint::Solid(color),
+}
diff --git a/src/library/page.rs b/src/library/page.rs
index 20871bd9..b256a521 100644
--- a/src/library/page.rs
+++ b/src/library/page.rs
@@ -12,13 +12,13 @@ pub fn page(ctx: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     let paper = args.named::<Paper>("paper")?.or_else(|| args.find());
     let width = args.named("width")?;
     let height = args.named("height")?;
+    let flip = args.named("flip")?;
     let margins = args.named("margins")?;
     let left = args.named("left")?;
     let top = args.named("top")?;
     let right = args.named("right")?;
     let bottom = args.named("bottom")?;
-    let flip = args.named("flip")?;
-    let fill = args.named("fill")?.map(Paint::Solid);
+    let fill = args.named("fill")?;
 
     ctx.template.modify(move |style| {
         let page = style.page_mut();
@@ -33,37 +33,37 @@ pub fn page(ctx: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
             page.size.w = width;
         }
 
+        if flip.unwrap_or(false) {
+            std::mem::swap(&mut page.size.w, &mut page.size.h);
+        }
+
         if let Some(height) = height {
             page.class = PaperClass::Custom;
             page.size.h = height;
         }
 
         if let Some(margins) = margins {
-            page.margins = Sides::splat(Some(margins));
+            page.margins = Sides::splat(margins);
         }
 
         if let Some(left) = left {
-            page.margins.left = Some(left);
+            page.margins.left = left;
         }
 
         if let Some(top) = top {
-            page.margins.top = Some(top);
+            page.margins.top = top;
         }
 
         if let Some(right) = right {
-            page.margins.right = Some(right);
+            page.margins.right = right;
         }
 
         if let Some(bottom) = bottom {
-            page.margins.bottom = Some(bottom);
-        }
-
-        if flip.unwrap_or(false) {
-            std::mem::swap(&mut page.size.w, &mut page.size.h);
+            page.margins.bottom = bottom;
         }
 
         if let Some(fill) = fill {
-            page.fill = Some(fill);
+            page.fill = fill;
         }
     });
 
diff --git a/src/library/shape.rs b/src/library/shape.rs
index abf927e4..f47da82f 100644
--- a/src/library/shape.rs
+++ b/src/library/shape.rs
@@ -58,11 +58,11 @@ fn shape_impl(
     };
 
     // Parse fill & stroke.
-    let fill = args.named("fill")?.map(Paint::Solid);
+    let fill = args.named("fill")?.unwrap_or(None);
     let stroke = match (args.named("stroke")?, args.named("thickness")?) {
         (None, None) => fill.is_none().then(|| default),
-        (color, thickness) => Some(Stroke {
-            paint: color.map(Paint::Solid).unwrap_or(default.paint),
+        (color, thickness) => color.unwrap_or(Some(default.paint)).map(|paint| Stroke {
+            paint,
             thickness: thickness.unwrap_or(default.thickness),
         }),
     };
diff --git a/src/library/text.rs b/src/library/text.rs
index d0b5c8e6..c0ee80e1 100644
--- a/src/library/text.rs
+++ b/src/library/text.rs
@@ -93,18 +93,16 @@ pub fn font(ctx: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 
     castable! {
         StylisticSet,
-        Expected: "none or integer",
-        Value::None => Self(None),
+        Expected: "integer",
         Value::Int(v) => match v {
-            1 ..= 20 => Self(Some(v as u8)),
+            1 ..= 20 => Self::new(v as u8),
             _ => Err("must be between 1 and 20")?,
         },
     }
 
     castable! {
         NumberType,
-        Expected: "auto or string",
-        Value::Auto => Self::Auto,
+        Expected: "string",
         Value::Str(string) => match string.as_str() {
             "lining" => Self::Lining,
             "old-style" => Self::OldStyle,
@@ -114,8 +112,7 @@ pub fn font(ctx: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 
     castable! {
         NumberWidth,
-        Expected: "auto or string",
-        Value::Auto => Self::Auto,
+        Expected: "string",
         Value::Str(string) => match string.as_str() {
             "proportional" => Self::Proportional,
             "tabular" => Self::Tabular,
@@ -629,8 +626,8 @@ fn tags(features: &FontFeatures) -> Vec<Feature> {
     }
 
     let storage;
-    if let StylisticSet(Some(set @ 1 ..= 20)) = features.stylistic_set {
-        storage = [b's', b's', b'0' + set / 10, b'0' + set % 10];
+    if let Some(set) = features.stylistic_set {
+        storage = [b's', b's', b'0' + set.get() / 10, b'0' + set.get() % 10];
         feat(&storage, 1);
     }
 
@@ -648,15 +645,15 @@ fn tags(features: &FontFeatures) -> Vec<Feature> {
     }
 
     match features.numbers.type_ {
-        NumberType::Auto => {}
-        NumberType::Lining => feat(b"lnum", 1),
-        NumberType::OldStyle => feat(b"onum", 1),
+        Smart::Auto => {}
+        Smart::Custom(NumberType::Lining) => feat(b"lnum", 1),
+        Smart::Custom(NumberType::OldStyle) => feat(b"onum", 1),
     }
 
     match features.numbers.width {
-        NumberWidth::Auto => {}
-        NumberWidth::Proportional => feat(b"pnum", 1),
-        NumberWidth::Tabular => feat(b"tnum", 1),
+        Smart::Auto => {}
+        Smart::Custom(NumberWidth::Proportional) => feat(b"pnum", 1),
+        Smart::Custom(NumberWidth::Tabular) => feat(b"tnum", 1),
     }
 
     match features.numbers.position {
diff --git a/src/style/mod.rs b/src/style/mod.rs
index 4a8830f8..45dbeb54 100644
--- a/src/style/mod.rs
+++ b/src/style/mod.rs
@@ -9,6 +9,7 @@ use std::rc::Rc;
 
 use ttf_parser::Tag;
 
+use crate::eval::Smart;
 use crate::font::*;
 use crate::geom::*;
 use crate::util::EcoString;
@@ -70,7 +71,7 @@ pub struct PageStyle {
     pub size: Size,
     /// The amount of white space on each side of the page. If a side is set to
     /// `None`, the default for the paper class is used.
-    pub margins: Sides<Option<Linear>>,
+    pub margins: Sides<Smart<Linear>>,
     /// The background fill of the page.
     pub fill: Option<Paint>,
 }
@@ -94,7 +95,7 @@ impl Default for PageStyle {
         Self {
             class: paper.class(),
             size: paper.size(),
-            margins: Sides::splat(None),
+            margins: Sides::splat(Smart::Auto),
             fill: None,
         }
     }
@@ -301,7 +302,7 @@ pub struct FontFeatures {
     /// Whether to apply stylistic alternates. ("salt")
     pub alternates: bool,
     /// Which stylistic set to apply. ("ss01" - "ss20")
-    pub stylistic_set: StylisticSet,
+    pub stylistic_set: Option<StylisticSet>,
     /// Configuration of ligature features.
     pub ligatures: LigatureFeatures,
     /// Configuration of numbers features.
@@ -316,7 +317,7 @@ impl Default for FontFeatures {
             kerning: true,
             smallcaps: false,
             alternates: false,
-            stylistic_set: StylisticSet::default(),
+            stylistic_set: None,
             ligatures: LigatureFeatures::default(),
             numbers: NumberFeatures::default(),
             raw: vec![],
@@ -326,11 +327,17 @@ impl Default for FontFeatures {
 
 /// A stylistic set in a font face.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
-pub struct StylisticSet(pub Option<u8>);
+pub struct StylisticSet(u8);
 
-impl Default for StylisticSet {
-    fn default() -> Self {
-        Self(None)
+impl StylisticSet {
+    /// Creates a new set, clamping to 1-20.
+    pub fn new(index: u8) -> Self {
+        Self(index.clamp(1, 20))
+    }
+
+    /// Get the value, guaranteed to be 1-20.
+    pub fn get(self) -> u8 {
+        self.0
     }
 }
 
@@ -359,9 +366,9 @@ impl Default for LigatureFeatures {
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub struct NumberFeatures {
     /// Whether to use lining or old-style numbers.
-    pub type_: NumberType,
+    pub type_: Smart<NumberType>,
     /// Whether to use proportional or tabular numbers.
-    pub width: NumberWidth,
+    pub width: Smart<NumberWidth>,
     /// How to position numbers vertically.
     pub position: NumberPosition,
     /// Whether to have a slash through the zero glyph. ("zero")
@@ -373,8 +380,8 @@ pub struct NumberFeatures {
 impl Default for NumberFeatures {
     fn default() -> Self {
         Self {
-            type_: NumberType::Auto,
-            width: NumberWidth::Auto,
+            type_: Smart::Auto,
+            width: Smart::Auto,
             position: NumberPosition::Normal,
             slashed_zero: false,
             fractions: false,
@@ -385,8 +392,6 @@ impl Default for NumberFeatures {
 /// Which kind of numbers / figures to select.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub enum NumberType {
-    /// Select the font's preference.
-    Auto,
     /// Numbers that fit well with capital text. ("lnum")
     Lining,
     /// Numbers that fit well into flow of upper- and lowercase text. ("onum")
@@ -396,8 +401,6 @@ pub enum NumberType {
 /// The width of numbers / figures.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub enum NumberWidth {
-    /// Select the font's preference.
-    Auto,
     /// Number widths are glyph specific. ("pnum")
     Proportional,
     /// All numbers are of equal width / monospaced. ("tnum")
diff --git a/tests/ref/elements/fill-stroke.png b/tests/ref/elements/fill-stroke.png
new file mode 100644
index 00000000..2d04b3dd
--- /dev/null
+++ b/tests/ref/elements/fill-stroke.png
diff --git a/tests/ref/layout/page.png b/tests/ref/layout/page.png
index dae3d488..57e4b8f1 100644
--- a/tests/ref/layout/page.png
+++ b/tests/ref/layout/page.png
diff --git a/tests/ref/layout/pagebreak.png b/tests/ref/layout/pagebreak.png
index 043b5086..fbb1d00c 100644
--- a/tests/ref/layout/pagebreak.png
+++ b/tests/ref/layout/pagebreak.png
diff --git a/tests/typ/elements/fill-stroke.typ b/tests/typ/elements/fill-stroke.typ
new file mode 100644
index 00000000..b8f2b4bc
--- /dev/null
+++ b/tests/typ/elements/fill-stroke.typ
@@ -0,0 +1,26 @@
+// Test shape fill & stroke.
+
+---
+#let rect with (width: 20pt, height: 10pt)
+#let items = for i, rect in (
+  rect(stroke: none),
+  rect(),
+  rect(fill: none),
+  rect(thickness: 2pt),
+  rect(stroke: eastern),
+  rect(stroke: eastern, thickness: 2pt),
+  rect(fill: eastern),
+  rect(fill: eastern, stroke: none),
+  rect(fill: forest, stroke: none, thickness: 2pt),
+  rect(fill: forest, stroke: conifer),
+  rect(fill: forest, thickness: 2pt),
+  rect(fill: forest, stroke: conifer, thickness: 2pt),
+) {
+  (align(vertical: center)[{i + 1}.], rect, [])
+}
+
+#grid(
+  columns: (auto, auto, 1fr, auto, auto, 0fr),
+  gutter: 5pt,
+  ..items,
+)
diff --git a/tests/typ/layout/page.typ b/tests/typ/layout/page.typ
index 9bb3097d..1f707327 100644
--- a/tests/typ/layout/page.typ
+++ b/tests/typ/layout/page.typ
@@ -27,20 +27,8 @@
 [#page(paper: "a11", flip: true) Flipped A11]
 
 ---
-// Test a combination of pages with bodies and normal content.
-
-#page(width: 80pt, height: 30pt)
-
-[#page() First]
-[#page() Second]
-#pagebreak()
-#pagebreak()
-Fourth
-[#page(height: 25pt)]
-Sixth
-[#page() Seventh]
-
----
 #page(width: 80pt, height: 40pt, fill: eastern)
-#font(15pt, "Roboto", fill: white, smallcaps: true)
-Typst
+#font(15pt, "Roboto", fill: white, smallcaps: true)[Typst]
+
+#page(width: 40pt, fill: none, margins: auto, top: 10pt)
+Hi
diff --git a/tests/typ/layout/pagebreak.typ b/tests/typ/layout/pagebreak.typ
index ab591c87..f9a935bc 100644
--- a/tests/typ/layout/pagebreak.typ
+++ b/tests/typ/layout/pagebreak.typ
@@ -18,3 +18,17 @@ C
 // No consequences from the page("A4") call here.
 #pagebreak()
 D
+
+---
+// Test a combination of pages with bodies and normal content.
+
+#page(width: 80pt, height: 30pt)
+
+[#page() First]
+[#page() Second]
+#pagebreak()
+#pagebreak()
+Fourth
+[#page(height: 25pt)]
+Sixth
+[#page() Seventh]
diff --git a/tests/typ/text/features.typ b/tests/typ/text/features.typ
index fc84514b..d60583d8 100644
--- a/tests/typ/text/features.typ
+++ b/tests/typ/text/features.typ
@@ -53,10 +53,18 @@ fi vs. #font(ligatures: false)[No fi] \
 fi vs. #font(features: (liga: 0))[No fi]
 
 ---
+// Error: 22-27 expected integer or none, found boolean
+#font(stylistic-set: false)
+
+---
 // Error: 22-24 must be between 1 and 20
 #font(stylistic-set: 25)
 
 ---
+// Error: 20-21 expected string or auto, found integer
+#font(number-type: 2)
+
+---
 // Error: 20-31 expected "lining" or "old-style"
 #font(number-type: "different")
 
diff --git a/tests/typeset.rs b/tests/typeset.rs
index 723df4a8..6a21cf7b 100644
--- a/tests/typeset.rs
+++ b/tests/typeset.rs
@@ -10,7 +10,7 @@ use ttf_parser::{GlyphId, OutlineBuilder};
 use walkdir::WalkDir;
 
 use typst::diag::Error;
-use typst::eval::Value;
+use typst::eval::{Smart, Value};
 use typst::font::Face;
 use typst::frame::{Element, Frame, Geometry, Shape, Stroke, Text};
 use typst::geom::{self, Color, Length, Paint, PathElement, RgbaColor, Sides, Size};
@@ -64,7 +64,7 @@ fn main() {
     // large and fit them to match their content.
     let mut style = Style::default();
     style.page_mut().size = Size::new(Length::pt(120.0), Length::inf());
-    style.page_mut().margins = Sides::splat(Some(Length::pt(10.0).into()));
+    style.page_mut().margins = Sides::splat(Smart::Custom(Length::pt(10.0).into()));
     style.text_mut().size = Length::pt(10.0);
 
     // Hook up an assert function into the global scope.