Improve value casting infrastructure

6 files changed, 72 insertions, 100 deletions

diff --git a/library/src/math/accent.rs b/library/src/math/accent.rs
index 7878782b..4a12f5c5 100644
--- a/library/src/math/accent.rs
+++ b/library/src/math/accent.rs
@@ -128,15 +128,12 @@ impl Accent {
     }
 }
 
-cast_from_value! {
+cast! {
     Accent,
+    self => self.0.into_value(),
     v: char => Self::new(v),
     v: Content => match v.to::<TextElem>() {
         Some(elem) => Value::Str(elem.text().into()).cast()?,
         None => Err("expected text")?,
     },
 }
-
-cast_to_value! {
-    v: Accent => v.0.into()
-}
diff --git a/library/src/math/delimited.rs b/library/src/math/delimited.rs
index 403f7922..08d18a5e 100644
--- a/library/src/math/delimited.rs
+++ b/library/src/math/delimited.rs
@@ -113,12 +113,11 @@ fn scale(
 ///
 /// Display: Floor
 /// Category: math
-/// Returns: content
 #[func]
 pub fn floor(
     /// The expression to floor.
     body: Content,
-) -> Value {
+) -> Content {
     delimited(body, '⌊', '⌋')
 }
 
@@ -131,12 +130,11 @@ pub fn floor(
 ///
 /// Display: Ceil
 /// Category: math
-/// Returns: content
 #[func]
 pub fn ceil(
     /// The expression to ceil.
     body: Content,
-) -> Value {
+) -> Content {
     delimited(body, '⌈', '⌉')
 }
 
@@ -149,12 +147,11 @@ pub fn ceil(
 ///
 /// Display: Round
 /// Category: math
-/// Returns: content
 #[func]
 pub fn round(
     /// The expression to round.
     body: Content,
-) -> Value {
+) -> Content {
     delimited(body, '⌊', '⌉')
 }
 
@@ -168,12 +165,11 @@ pub fn round(
 ///
 /// Display: Abs
 /// Category: math
-/// Returns: content
 #[func]
 pub fn abs(
     /// The expression to take the absolute value of.
     body: Content,
-) -> Value {
+) -> Content {
     delimited(body, '|', '|')
 }
 
@@ -186,21 +182,19 @@ pub fn abs(
 ///
 /// Display: Norm
 /// Category: math
-/// Returns: content
 #[func]
 pub fn norm(
     /// The expression to take the norm of.
     body: Content,
-) -> Value {
+) -> Content {
     delimited(body, '‖', '‖')
 }
 
-fn delimited(body: Content, left: char, right: char) -> Value {
+fn delimited(body: Content, left: char, right: char) -> Content {
     LrElem::new(Content::sequence([
         TextElem::packed(left),
         body,
         TextElem::packed(right),
     ]))
     .pack()
-    .into()
 }
diff --git a/library/src/math/mod.rs b/library/src/math/mod.rs
index 3ea96cfa..4ab23f23 100644
--- a/library/src/math/mod.rs
+++ b/library/src/math/mod.rs
@@ -59,11 +59,11 @@ pub fn module() -> Module {
 
     // Grouping.
     math.define("lr", LrElem::func());
-    math.define("abs", abs);
-    math.define("norm", norm);
-    math.define("floor", floor);
-    math.define("ceil", ceil);
-    math.define("round", round);
+    math.define("abs", abs_func());
+    math.define("norm", norm_func());
+    math.define("floor", floor_func());
+    math.define("ceil", ceil_func());
+    math.define("round", round_func());
 
     // Attachments and accents.
     math.define("attach", AttachElem::func());
@@ -86,24 +86,24 @@ pub fn module() -> Module {
     math.define("cases", CasesElem::func());
 
     // Roots.
-    math.define("sqrt", sqrt);
+    math.define("sqrt", sqrt_func());
     math.define("root", RootElem::func());
 
     // Styles.
-    math.define("upright", upright);
-    math.define("bold", bold);
-    math.define("italic", italic);
-    math.define("serif", serif);
-    math.define("sans", sans);
-    math.define("cal", cal);
-    math.define("frak", frak);
-    math.define("mono", mono);
-    math.define("bb", bb);
-
-    math.define("display", display);
-    math.define("inline", inline);
-    math.define("script", script);
-    math.define("sscript", sscript);
+    math.define("upright", upright_func());
+    math.define("bold", bold_func());
+    math.define("italic", italic_func());
+    math.define("serif", serif_func());
+    math.define("sans", sans_func());
+    math.define("cal", cal_func());
+    math.define("frak", frak_func());
+    math.define("mono", mono_func());
+    math.define("bb", bb_func());
+
+    math.define("display", display_func());
+    math.define("inline", inline_func());
+    math.define("script", script_func());
+    math.define("sscript", sscript_func());
 
     // Text operators.
     math.define("op", OpElem::func());
@@ -197,9 +197,7 @@ impl Synthesize for EquationElem {
         let supplement = match self.supplement(styles) {
             Smart::Auto => TextElem::packed(self.local_name_in(styles)),
             Smart::Custom(None) => Content::empty(),
-            Smart::Custom(Some(supplement)) => {
-                supplement.resolve(vt, [self.clone().into()])?
-            }
+            Smart::Custom(Some(supplement)) => supplement.resolve(vt, [self.clone()])?,
         };
 
         self.push_block(self.block(styles));
diff --git a/library/src/math/root.rs b/library/src/math/root.rs
index 05f3a2a7..d1c5f46a 100644
--- a/library/src/math/root.rs
+++ b/library/src/math/root.rs
@@ -9,13 +9,12 @@ use super::*;
 ///
 /// Display: Square Root
 /// Category: math
-/// Returns: content
 #[func]
 pub fn sqrt(
     /// The expression to take the square root of.
     radicand: Content,
-) -> Value {
-    RootElem::new(radicand).pack().into()
+) -> Content {
+    RootElem::new(radicand).pack()
 }
 
 /// A general root.
diff --git a/library/src/math/row.rs b/library/src/math/row.rs
index 9b693bc1..6e666e89 100644
--- a/library/src/math/row.rs
+++ b/library/src/math/row.rs
@@ -233,3 +233,22 @@ impl<T: Into<MathFragment>> From<T> for MathRow {
         Self(vec![fragment.into()])
     }
 }
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+enum LeftRightAlternator {
+    Left,
+    Right,
+}
+
+impl Iterator for LeftRightAlternator {
+    type Item = LeftRightAlternator;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let r = Some(*self);
+        match self {
+            Self::Left => *self = Self::Right,
+            Self::Right => *self = Self::Left,
+        }
+        r
+    }
+}
diff --git a/library/src/math/style.rs b/library/src/math/style.rs
index e0e1ccad..05ff64dc 100644
--- a/library/src/math/style.rs
+++ b/library/src/math/style.rs
@@ -9,13 +9,12 @@ use super::*;
 ///
 /// Display: Bold
 /// Category: math
-/// Returns: content
 #[func]
 pub fn bold(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body).with_bold(Some(true)).pack().into()
+) -> Content {
+    MathStyleElem::new(body).with_bold(Some(true)).pack()
 }
 
 /// Upright (non-italic) font style in math.
@@ -27,13 +26,12 @@ pub fn bold(
 ///
 /// Display: Upright
 /// Category: math
-/// Returns: content
 #[func]
 pub fn upright(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body).with_italic(Some(false)).pack().into()
+) -> Content {
+    MathStyleElem::new(body).with_italic(Some(false)).pack()
 }
 
 /// Italic font style in math.
@@ -42,13 +40,12 @@ pub fn upright(
 ///
 /// Display: Italic
 /// Category: math
-/// Returns: content
 #[func]
 pub fn italic(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body).with_italic(Some(true)).pack().into()
+) -> Content {
+    MathStyleElem::new(body).with_italic(Some(true)).pack()
 }
 /// Serif (roman) font style in math.
 ///
@@ -56,16 +53,12 @@ pub fn italic(
 ///
 /// Display: Serif
 /// Category: math
-/// Returns: content
 #[func]
 pub fn serif(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body)
-        .with_variant(Some(MathVariant::Serif))
-        .pack()
-        .into()
+) -> Content {
+    MathStyleElem::new(body).with_variant(Some(MathVariant::Serif)).pack()
 }
 
 /// Sans-serif font style in math.
@@ -77,16 +70,12 @@ pub fn serif(
 ///
 /// Display: Sans-serif
 /// Category: math
-/// Returns: content
 #[func]
 pub fn sans(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body)
-        .with_variant(Some(MathVariant::Sans))
-        .pack()
-        .into()
+) -> Content {
+    MathStyleElem::new(body).with_variant(Some(MathVariant::Sans)).pack()
 }
 
 /// Calligraphic font style in math.
@@ -98,16 +87,12 @@ pub fn sans(
 ///
 /// Display: Calligraphic
 /// Category: math
-/// Returns: content
 #[func]
 pub fn cal(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body)
-        .with_variant(Some(MathVariant::Cal))
-        .pack()
-        .into()
+) -> Content {
+    MathStyleElem::new(body).with_variant(Some(MathVariant::Cal)).pack()
 }
 
 /// Fraktur font style in math.
@@ -119,16 +104,12 @@ pub fn cal(
 ///
 /// Display: Fraktur
 /// Category: math
-/// Returns: content
 #[func]
 pub fn frak(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body)
-        .with_variant(Some(MathVariant::Frak))
-        .pack()
-        .into()
+) -> Content {
+    MathStyleElem::new(body).with_variant(Some(MathVariant::Frak)).pack()
 }
 
 /// Monospace font style in math.
@@ -140,16 +121,12 @@ pub fn frak(
 ///
 /// Display: Monospace
 /// Category: math
-/// Returns: content
 #[func]
 pub fn mono(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body)
-        .with_variant(Some(MathVariant::Mono))
-        .pack()
-        .into()
+) -> Content {
+    MathStyleElem::new(body).with_variant(Some(MathVariant::Mono)).pack()
 }
 
 /// Blackboard bold (double-struck) font style in math.
@@ -166,16 +143,12 @@ pub fn mono(
 ///
 /// Display: Blackboard Bold
 /// Category: math
-/// Returns: content
 #[func]
 pub fn bb(
     /// The content to style.
     body: Content,
-) -> Value {
-    MathStyleElem::new(body)
-        .with_variant(Some(MathVariant::Bb))
-        .pack()
-        .into()
+) -> Content {
+    MathStyleElem::new(body).with_variant(Some(MathVariant::Bb)).pack()
 }
 
 /// Forced display style in math.
@@ -189,7 +162,6 @@ pub fn bb(
 ///
 /// Display: Display Size
 /// Category: math
-/// Returns: content
 #[func]
 pub fn display(
     /// The content to size.
@@ -199,12 +171,11 @@ pub fn display(
     #[named]
     #[default(false)]
     cramp: bool,
-) -> Value {
+) -> Content {
     MathStyleElem::new(body)
         .with_size(Some(MathSize::Display))
         .with_cramp(Some(cramp))
         .pack()
-        .into()
 }
 
 /// Forced inline (text) style in math.
@@ -219,7 +190,6 @@ pub fn display(
 ///
 /// Display: Inline Size
 /// Category: math
-/// Returns: content
 #[func]
 pub fn inline(
     /// The content to size.
@@ -229,12 +199,11 @@ pub fn inline(
     #[named]
     #[default(false)]
     cramp: bool,
-) -> Value {
+) -> Content {
     MathStyleElem::new(body)
         .with_size(Some(MathSize::Text))
         .with_cramp(Some(cramp))
         .pack()
-        .into()
 }
 
 /// Forced script style in math.
@@ -248,7 +217,6 @@ pub fn inline(
 ///
 /// Display: Script Size
 /// Category: math
-/// Returns: content
 #[func]
 pub fn script(
     /// The content to size.
@@ -258,12 +226,11 @@ pub fn script(
     #[named]
     #[default(true)]
     cramp: bool,
-) -> Value {
+) -> Content {
     MathStyleElem::new(body)
         .with_size(Some(MathSize::Script))
         .with_cramp(Some(cramp))
         .pack()
-        .into()
 }
 
 /// Forced second script style in math.
@@ -278,7 +245,6 @@ pub fn script(
 ///
 /// Display: Script-Script Size
 /// Category: math
-/// Returns: content
 #[func]
 pub fn sscript(
     /// The content to size.
@@ -288,12 +254,11 @@ pub fn sscript(
     #[named]
     #[default(true)]
     cramp: bool,
-) -> Value {
+) -> Content {
     MathStyleElem::new(body)
         .with_size(Some(MathSize::ScriptScript))
         .with_cramp(Some(cramp))
         .pack()
-        .into()
 }
 
 /// A font variant in math.