Split `show` into `realize` and `finalize`

10 files changed, 166 insertions, 171 deletions

diff --git a/src/eval/content.rs b/src/eval/content.rs
index 098bfbfc..2465f0e3 100644
--- a/src/eval/content.rs
+++ b/src/eval/content.rs
@@ -104,6 +104,23 @@ impl Content {
         Self::Show(node.pack())
     }
 
+    /// Create a new sequence nodes from multiples nodes.
+    pub fn sequence(seq: Vec<Self>) -> Self {
+        if seq.len() == 1 {
+            seq.into_iter().next().unwrap()
+        } else {
+            Self::Sequence(Arc::new(seq))
+        }
+    }
+
+    /// Repeat this content `n` times.
+    pub fn repeat(&self, n: i64) -> StrResult<Self> {
+        let count = usize::try_from(n)
+            .map_err(|_| format!("cannot repeat this content {} times", n))?;
+
+        Ok(Self::sequence(vec![self.clone(); count]))
+    }
+
     /// Style this content with a single style property.
     pub fn styled<'k, K: Key<'k>>(mut self, key: K, value: K::Value) -> Self {
         if let Self::Styled(styled) = &mut self {
@@ -137,21 +154,24 @@ impl Content {
         Self::show(DecoNode::<UNDERLINE>(self))
     }
 
-    /// Create a new sequence nodes from multiples nodes.
-    pub fn sequence(seq: Vec<Self>) -> Self {
-        if seq.len() == 1 {
-            seq.into_iter().next().unwrap()
-        } else {
-            Self::Sequence(Arc::new(seq))
+    /// Return a node that is spaced apart at top and bottom.
+    pub fn spaced(self, above: Length, below: Length) -> Self {
+        if above.is_zero() && below.is_zero() {
+            return self;
         }
-    }
 
-    /// Repeat this content `n` times.
-    pub fn repeat(&self, n: i64) -> StrResult<Self> {
-        let count = usize::try_from(n)
-            .map_err(|_| format!("cannot repeat this content {} times", n))?;
+        let mut seq = vec![];
+        if !above.is_zero() {
+            seq.push(Content::Vertical(above.into()));
+        }
 
-        Ok(Self::sequence(vec![self.clone(); count]))
+        seq.push(self);
+
+        if !below.is_zero() {
+            seq.push(Content::Vertical(below.into()));
+        }
+
+        Self::sequence(seq)
     }
 
     /// Layout this content into a collection of pages.
@@ -454,8 +474,11 @@ impl<'a> Builder<'a> {
             }
             Content::Show(node) => {
                 let id = node.id();
-                let realized = styles.realize(ctx, node)?;
-                let content = node.show(ctx, styles, realized)?;
+                let realized = match styles.realize(ctx, node)? {
+                    Some(content) => content,
+                    None => node.realize(ctx, styles)?,
+                };
+                let content = node.finalize(ctx, styles, realized)?;
                 let stored = self.tpa.alloc(content);
                 self.process(ctx, stored, styles.unscoped(id))?;
             }
diff --git a/src/eval/show.rs b/src/eval/show.rs
index f8d98d52..c374c2df 100644
--- a/src/eval/show.rs
+++ b/src/eval/show.rs
@@ -13,14 +13,26 @@ pub trait Show: 'static {
     /// Encode this node into a dictionary.
     fn encode(&self) -> Dict;
 
-    /// Show this node in the given styles and optionally given the realization
-    /// of a show rule.
-    fn show(
+    /// The base recipe for this node that is executed if there is no
+    /// user-defined show rule.
+    fn realize(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Content>;
+
+    /// Finalize this node given the realization of a base or user recipe. Use
+    /// this for effects that should work even in the face of a user-defined
+    /// show rule, for example:
+    /// - Application of general settable properties
+    /// - Attaching things like semantics to a heading
+    ///
+    /// Defaults to just the realized content.
+    #[allow(unused_variables)]
+    fn finalize(
         &self,
         ctx: &mut Context,
         styles: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content>;
+        realized: Content,
+    ) -> TypResult<Content> {
+        Ok(realized)
+    }
 
     /// Convert to a packed show node.
     fn pack(self) -> ShowNode
@@ -55,13 +67,17 @@ impl Show for ShowNode {
         self.0.encode()
     }
 
-    fn show(
+    fn realize(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Content> {
+        self.0.realize(ctx, styles)
+    }
+
+    fn finalize(
         &self,
         ctx: &mut Context,
         styles: StyleChain,
-        realized: Option<Content>,
+        realized: Content,
     ) -> TypResult<Content> {
-        self.0.show(ctx, styles, realized)
+        self.0.finalize(ctx, styles, realized)
     }
 
     fn pack(self) -> ShowNode {
diff --git a/src/library/math/mod.rs b/src/library/math/mod.rs
index 587949d7..345bb3f6 100644
--- a/src/library/math/mod.rs
+++ b/src/library/math/mod.rs
@@ -35,26 +35,27 @@ impl Show for MathNode {
         }
     }
 
-    fn show(
+    fn realize(&self, _: &mut Context, _: StyleChain) -> TypResult<Content> {
+        Ok(Content::Text(self.formula.trim().into()))
+    }
+
+    fn finalize(
         &self,
         _: &mut Context,
         styles: StyleChain,
-        realized: Option<Content>,
+        mut realized: Content,
     ) -> TypResult<Content> {
-        let mut content =
-            realized.unwrap_or_else(|| Content::Text(self.formula.trim().into()));
-
         let mut map = StyleMap::new();
         if let Smart::Custom(family) = styles.get(Self::FAMILY) {
             map.set_family(family.clone(), styles);
         }
 
-        content = content.styled_with_map(map);
+        realized = realized.styled_with_map(map);
 
         if self.display {
-            content = Content::Block(content.pack());
+            realized = Content::block(realized);
         }
 
-        Ok(content)
+        Ok(realized)
     }
 }
diff --git a/src/library/structure/heading.rs b/src/library/structure/heading.rs
index a352cc92..a6c87912 100644
--- a/src/library/structure/heading.rs
+++ b/src/library/structure/heading.rs
@@ -63,11 +63,15 @@ impl Show for HeadingNode {
         }
     }
 
-    fn show(
+    fn realize(&self, _: &mut Context, _: StyleChain) -> TypResult<Content> {
+        Ok(self.body.clone())
+    }
+
+    fn finalize(
         &self,
         ctx: &mut Context,
         styles: StyleChain,
-        realized: Option<Content>,
+        mut realized: Content,
     ) -> TypResult<Content> {
         macro_rules! resolve {
             ($key:expr) => {
@@ -75,8 +79,6 @@ impl Show for HeadingNode {
             };
         }
 
-        let mut body = realized.unwrap_or_else(|| self.body.clone());
-
         let mut map = StyleMap::new();
         map.set(TextNode::SIZE, resolve!(Self::SIZE));
 
@@ -96,30 +98,22 @@ impl Show for HeadingNode {
             map.set(TextNode::EMPH, Toggle);
         }
 
-        let mut seq = vec![];
         if resolve!(Self::UNDERLINE) {
-            body = body.underlined();
-        }
-
-        let above = resolve!(Self::ABOVE);
-        if !above.is_zero() {
-            seq.push(Content::Vertical(above.resolve(styles).into()));
+            realized = realized.underlined();
         }
 
-        seq.push(body);
-
-        let below = resolve!(Self::BELOW);
-        if !below.is_zero() {
-            seq.push(Content::Vertical(below.resolve(styles).into()));
-        }
-
-        let mut content = Content::sequence(seq).styled_with_map(map);
+        realized = realized.styled_with_map(map);
 
         if resolve!(Self::BLOCK) {
-            content = Content::block(content);
+            realized = Content::block(realized);
         }
 
-        Ok(content)
+        realized = realized.spaced(
+            resolve!(Self::ABOVE).resolve(styles),
+            resolve!(Self::BELOW).resolve(styles),
+        );
+
+        Ok(realized)
     }
 }
 
diff --git a/src/library/structure/list.rs b/src/library/structure/list.rs
index c59b443d..6655175f 100644
--- a/src/library/structure/list.rs
+++ b/src/library/structure/list.rs
@@ -79,66 +79,51 @@ impl<const L: ListKind> Show for ListNode<L> {
         }
     }
 
-    fn show(
-        &self,
-        ctx: &mut Context,
-        styles: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content> {
-        let content = if let Some(content) = realized {
-            content
-        } else {
-            let mut cells = vec![];
-            let mut number = self.start;
-
-            let label = styles.get(Self::LABEL);
-
-            for item in &self.items {
-                number = item.number.unwrap_or(number);
-                cells.push(LayoutNode::default());
-                cells.push(label.resolve(ctx, L, number)?.pack());
-                cells.push(LayoutNode::default());
-                cells.push((*item.body).clone().pack());
-                number += 1;
-            }
-
-            let leading = styles.get(ParNode::LEADING);
-            let spacing = if self.tight {
-                styles.get(Self::SPACING)
-            } else {
-                styles.get(ParNode::SPACING)
-            };
-
-            let gutter = leading + spacing;
-            let indent = styles.get(Self::INDENT);
-            let body_indent = styles.get(Self::BODY_INDENT);
-
-            Content::block(GridNode {
-                tracks: Spec::with_x(vec![
-                    TrackSizing::Relative(indent.into()),
-                    TrackSizing::Auto,
-                    TrackSizing::Relative(body_indent.into()),
-                    TrackSizing::Auto,
-                ]),
-                gutter: Spec::with_y(vec![TrackSizing::Relative(gutter.into())]),
-                cells,
-            })
-        };
-
-        let mut seq = vec![];
-        let above = styles.get(Self::ABOVE);
-        if !above.is_zero() {
-            seq.push(Content::Vertical(above.into()));
+    fn realize(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Content> {
+        let mut cells = vec![];
+        let mut number = self.start;
+
+        let label = styles.get(Self::LABEL);
+
+        for item in &self.items {
+            number = item.number.unwrap_or(number);
+            cells.push(LayoutNode::default());
+            cells.push(label.resolve(ctx, L, number)?.pack());
+            cells.push(LayoutNode::default());
+            cells.push((*item.body).clone().pack());
+            number += 1;
         }
 
-        seq.push(content);
+        let leading = styles.get(ParNode::LEADING);
+        let spacing = if self.tight {
+            styles.get(Self::SPACING)
+        } else {
+            styles.get(ParNode::SPACING)
+        };
 
-        let below = styles.get(Self::BELOW);
-        if !below.is_zero() {
-            seq.push(Content::Vertical(below.into()));
-        }
+        let gutter = leading + spacing;
+        let indent = styles.get(Self::INDENT);
+        let body_indent = styles.get(Self::BODY_INDENT);
+
+        Ok(Content::block(GridNode {
+            tracks: Spec::with_x(vec![
+                TrackSizing::Relative(indent.into()),
+                TrackSizing::Auto,
+                TrackSizing::Relative(body_indent.into()),
+                TrackSizing::Auto,
+            ]),
+            gutter: Spec::with_y(vec![TrackSizing::Relative(gutter.into())]),
+            cells,
+        }))
+    }
 
-        Ok(Content::sequence(seq))
+    fn finalize(
+        &self,
+        _: &mut Context,
+        styles: StyleChain,
+        realized: Content,
+    ) -> TypResult<Content> {
+        Ok(realized.spaced(styles.get(Self::ABOVE), styles.get(Self::BELOW)))
     }
 }
 
diff --git a/src/library/structure/table.rs b/src/library/structure/table.rs
index aefd01b5..191d3dd3 100644
--- a/src/library/structure/table.rs
+++ b/src/library/structure/table.rs
@@ -64,16 +64,7 @@ impl Show for TableNode {
         }
     }
 
-    fn show(
-        &self,
-        _: &mut Context,
-        styles: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content> {
-        if let Some(content) = realized {
-            return Ok(content);
-        }
-
+    fn realize(&self, _: &mut Context, styles: StyleChain) -> TypResult<Content> {
         let primary = styles.get(Self::PRIMARY);
         let secondary = styles.get(Self::SECONDARY);
         let stroke = styles.get(Self::STROKE).map(RawStroke::unwrap_or_default);
diff --git a/src/library/text/deco.rs b/src/library/text/deco.rs
index 9fe4e65a..52f8ea80 100644
--- a/src/library/text/deco.rs
+++ b/src/library/text/deco.rs
@@ -47,20 +47,13 @@ impl<const L: DecoLine> Show for DecoNode<L> {
         dict! { "body" => Value::Content(self.0.clone()) }
     }
 
-    fn show(
-        &self,
-        _: &mut Context,
-        styles: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content> {
-        Ok(realized.unwrap_or_else(|| {
-            self.0.clone().styled(TextNode::DECO, Decoration {
-                line: L,
-                stroke: styles.get(Self::STROKE).unwrap_or_default(),
-                offset: styles.get(Self::OFFSET),
-                extent: styles.get(Self::EXTENT),
-                evade: styles.get(Self::EVADE),
-            })
+    fn realize(&self, _: &mut Context, styles: StyleChain) -> TypResult<Content> {
+        Ok(self.0.clone().styled(TextNode::DECO, Decoration {
+            line: L,
+            stroke: styles.get(Self::STROKE).unwrap_or_default(),
+            offset: styles.get(Self::OFFSET),
+            extent: styles.get(Self::EXTENT),
+            evade: styles.get(Self::EVADE),
         }))
     }
 }
diff --git a/src/library/text/link.rs b/src/library/text/link.rs
index d1e5eb8e..710fbc47 100644
--- a/src/library/text/link.rs
+++ b/src/library/text/link.rs
@@ -38,13 +38,8 @@ impl Show for LinkNode {
         }
     }
 
-    fn show(
-        &self,
-        _: &mut Context,
-        styles: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content> {
-        let mut body = realized.or_else(|| self.body.clone()).unwrap_or_else(|| {
+    fn realize(&self, _: &mut Context, _: StyleChain) -> TypResult<Content> {
+        Ok(self.body.clone().unwrap_or_else(|| {
             let url = &self.url;
             let mut text = url.as_str();
             for prefix in ["mailto:", "tel:"] {
@@ -52,8 +47,15 @@ impl Show for LinkNode {
             }
             let shorter = text.len() < url.len();
             Content::Text(if shorter { text.into() } else { url.clone() })
-        });
+        }))
+    }
 
+    fn finalize(
+        &self,
+        _: &mut Context,
+        styles: StyleChain,
+        mut realized: Content,
+    ) -> TypResult<Content> {
         let mut map = StyleMap::new();
         map.set(TextNode::LINK, Some(self.url.clone()));
 
@@ -62,9 +64,9 @@ impl Show for LinkNode {
         }
 
         if styles.get(Self::UNDERLINE) {
-            body = body.underlined();
+            realized = realized.underlined();
         }
 
-        Ok(body.styled_with_map(map))
+        Ok(realized.styled_with_map(map))
     }
 }
diff --git a/src/library/text/mod.rs b/src/library/text/mod.rs
index e477e76d..3cfbc55d 100644
--- a/src/library/text/mod.rs
+++ b/src/library/text/mod.rs
@@ -475,13 +475,8 @@ impl Show for StrongNode {
         dict! { "body" => Value::Content(self.0.clone()) }
     }
 
-    fn show(
-        &self,
-        _: &mut Context,
-        _: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content> {
-        Ok(realized.unwrap_or_else(|| self.0.clone().styled(TextNode::STRONG, Toggle)))
+    fn realize(&self, _: &mut Context, _: StyleChain) -> TypResult<Content> {
+        Ok(self.0.clone().styled(TextNode::STRONG, Toggle))
     }
 }
 
@@ -501,12 +496,7 @@ impl Show for EmphNode {
         dict! { "body" => Value::Content(self.0.clone()) }
     }
 
-    fn show(
-        &self,
-        _: &mut Context,
-        _: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content> {
-        Ok(realized.unwrap_or_else(|| self.0.clone().styled(TextNode::EMPH, Toggle)))
+    fn realize(&self, _: &mut Context, _: StyleChain) -> TypResult<Content> {
+        Ok(self.0.clone().styled(TextNode::EMPH, Toggle))
     }
 }
diff --git a/src/library/text/raw.rs b/src/library/text/raw.rs
index cc225bed..13daa1b9 100644
--- a/src/library/text/raw.rs
+++ b/src/library/text/raw.rs
@@ -50,12 +50,7 @@ impl Show for RawNode {
         }
     }
 
-    fn show(
-        &self,
-        _: &mut Context,
-        styles: StyleChain,
-        realized: Option<Content>,
-    ) -> TypResult<Content> {
+    fn realize(&self, _: &mut Context, styles: StyleChain) -> TypResult<Content> {
         let lang = styles.get(Self::LANG).as_ref();
         let foreground = THEME
             .settings
@@ -64,9 +59,7 @@ impl Show for RawNode {
             .unwrap_or(Color::BLACK)
             .into();
 
-        let mut content = if let Some(content) = realized {
-            content
-        } else if matches!(
+        if matches!(
             lang.map(|s| s.to_lowercase()).as_deref(),
             Some("typ" | "typst")
         ) {
@@ -79,7 +72,7 @@ impl Show for RawNode {
                 seq.push(styled(&self.text[range], foreground, style));
             });
 
-            Content::sequence(seq)
+            Ok(Content::sequence(seq))
         } else if let Some(syntax) =
             lang.and_then(|token| SYNTAXES.find_syntax_by_token(&token))
         {
@@ -95,11 +88,18 @@ impl Show for RawNode {
                 }
             }
 
-            Content::sequence(seq)
+            Ok(Content::sequence(seq))
         } else {
-            Content::Text(self.text.clone())
-        };
+            Ok(Content::Text(self.text.clone()))
+        }
+    }
 
+    fn finalize(
+        &self,
+        _: &mut Context,
+        styles: StyleChain,
+        mut realized: Content,
+    ) -> TypResult<Content> {
         let mut map = StyleMap::new();
         map.set(TextNode::OVERHANG, false);
         map.set(TextNode::HYPHENATE, Smart::Custom(Hyphenate(false)));
@@ -109,13 +109,13 @@ impl Show for RawNode {
             map.set_family(family.clone(), styles);
         }
 
-        content = content.styled_with_map(map);
+        realized = realized.styled_with_map(map);
 
         if self.block {
-            content = Content::Block(content.pack());
+            realized = Content::block(realized);
         }
 
-        Ok(content)
+        Ok(realized)
     }
 }