Tidy up styling

8 files changed, 71 insertions, 54 deletions

diff --git a/src/eval/class.rs b/src/eval/class.rs
index 7888cba2..b7b4d012 100644
--- a/src/eval/class.rs
+++ b/src/eval/class.rs
@@ -66,7 +66,7 @@ impl Class {
         let mut styles = StyleMap::new();
         self.set(args, &mut styles)?;
         let node = (self.construct)(ctx, args)?;
-        Ok(node.styled(styles))
+        Ok(node.styled_with_map(styles))
     }
 
     /// Execute the class's set rule.
diff --git a/src/eval/node.rs b/src/eval/node.rs
index 2c955d01..37f230ee 100644
--- a/src/eval/node.rs
+++ b/src/eval/node.rs
@@ -5,7 +5,7 @@ use std::iter::Sum;
 use std::mem;
 use std::ops::{Add, AddAssign};
 
-use super::{StyleMap, Styled};
+use super::{Property, StyleMap, Styled};
 use crate::diag::StrResult;
 use crate::geom::SpecAxis;
 use crate::layout::{Layout, PackedNode, RootNode};
@@ -84,14 +84,33 @@ impl Node {
         Self::Block(node.pack())
     }
 
-    /// Style this node.
-    pub fn styled(self, styles: StyleMap) -> Self {
+    /// Style this node with a single property.
+    pub fn styled<P: Property>(mut self, key: P, value: P::Value) -> Self {
+        if let Self::Sequence(vec) = &mut self {
+            if let [styled] = vec.as_mut_slice() {
+                styled.map.set(key, value);
+                return self;
+            }
+        }
+
+        self.styled_with_map(StyleMap::with(key, value))
+    }
+
+    /// Style this node with a full style map.
+    pub fn styled_with_map(mut self, styles: StyleMap) -> Self {
+        if let Self::Sequence(vec) = &mut self {
+            if let [styled] = vec.as_mut_slice() {
+                styled.map.apply(&styles);
+                return self;
+            }
+        }
+
         Self::Sequence(vec![Styled::new(self, styles)])
     }
 
     /// Style this node in monospace.
     pub fn monospaced(self) -> Self {
-        self.styled(StyleMap::with(TextNode::MONOSPACE, true))
+        self.styled(TextNode::MONOSPACE, true)
     }
 
     /// Lift to a type-erased block-level node.
diff --git a/src/eval/styles.rs b/src/eval/styles.rs
index 54ac2697..0f3d694a 100644
--- a/src/eval/styles.rs
+++ b/src/eval/styles.rs
@@ -106,7 +106,6 @@ impl StyleMap {
     /// `outer`. The ones from `self` take precedence over the ones from
     /// `outer`. For folded properties `self` contributes the inner value.
     pub fn chain<'a>(&'a self, outer: &'a StyleChain<'a>) -> StyleChain<'a> {
-        // No need to chain an empty map.
         if self.is_empty() {
             *outer
         } else {
@@ -182,7 +181,9 @@ impl PartialEq for StyleMap {
 /// matches further up the chain.
 #[derive(Clone, Copy, Hash)]
 pub struct StyleChain<'a> {
+    /// The first map in the chain.
     inner: &'a StyleMap,
+    /// The remaining maps in the chain.
     outer: Option<&'a Self>,
 }
 
@@ -238,14 +239,13 @@ impl<'a> StyleChain<'a> {
     /// entry for it.
     pub fn get_cloned<P: Property>(self, key: P) -> P::Value {
         if let Some(value) = self.find(key).cloned() {
-            if P::FOLDABLE {
-                if let Some(outer) = self.outer {
-                    P::fold(value, outer.get_cloned(key))
-                } else {
-                    P::fold(value, P::default())
-                }
-            } else {
-                value
+            if !P::FOLDABLE {
+                return value;
+            }
+
+            match self.outer {
+                Some(outer) => P::fold(value, outer.get_cloned(key)),
+                None => P::fold(value, P::default()),
             }
         } else if let Some(outer) = self.outer {
             outer.get_cloned(key)
diff --git a/src/library/link.rs b/src/library/link.rs
index 1050963c..b7e3d587 100644
--- a/src/library/link.rs
+++ b/src/library/link.rs
@@ -15,9 +15,9 @@ pub fn link(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
         Node::Text(text.into())
     });
 
-    let mut passed = StyleMap::new();
-    passed.set(TextNode::LINK, Some(url.clone()));
-    passed.set(ImageNode::LINK, Some(url.clone()));
-    passed.set(ShapeNode::LINK, Some(url));
-    Ok(Value::Node(body.styled(passed)))
+    let mut map = StyleMap::new();
+    map.set(TextNode::LINK, Some(url.clone()));
+    map.set(ImageNode::LINK, Some(url.clone()));
+    map.set(ShapeNode::LINK, Some(url));
+    Ok(Value::Node(body.styled_with_map(map)))
 }
diff --git a/src/library/mod.rs b/src/library/mod.rs
index 89f4ab9d..461716a1 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -61,8 +61,8 @@ prelude! {
 
     pub use crate::diag::{At, TypResult};
     pub use crate::eval::{
-        Args, Construct, EvalContext, Node, Property, Set, Smart, StyleChain, StyleMap,
-        Styled, Value,
+        Args, Construct, EvalContext, Node, Property, Scope, Set, Smart, StyleChain,
+        StyleMap, Styled, Value,
     };
     pub use crate::frame::*;
     pub use crate::geom::*;
@@ -73,52 +73,49 @@ prelude! {
     pub use crate::util::{EcoString, OptionExt};
 }
 
-use crate::eval::Scope;
 use prelude::*;
 
 /// Construct a scope containing all standard library definitions.
 pub fn new() -> Scope {
     let mut std = Scope::new();
 
-    // Classes.
+    // Structure and semantics.
     std.def_class::<PageNode>("page");
     std.def_class::<ParNode>("par");
     std.def_class::<TextNode>("text");
-    std.def_class::<HeadingNode>("heading");
-    std.def_class::<ListNode<Unordered>>("list");
-    std.def_class::<ListNode<Ordered>>("enum");
-
-    // Text functions.
     std.def_func("underline", underline);
     std.def_func("strike", strike);
     std.def_func("overline", overline);
     std.def_func("link", link);
+    std.def_class::<HeadingNode>("heading");
+    std.def_class::<ListNode<Unordered>>("list");
+    std.def_class::<ListNode<Ordered>>("enum");
+    std.def_func("image", image);
+    std.def_func("rect", rect);
+    std.def_func("square", square);
+    std.def_func("ellipse", ellipse);
+    std.def_func("circle", circle);
 
-    // Break and spacing functions.
-    std.def_func("pagebreak", pagebreak);
-    std.def_func("colbreak", colbreak);
-    std.def_func("parbreak", parbreak);
-    std.def_func("linebreak", linebreak);
+    // Layout.
     std.def_func("h", h);
     std.def_func("v", v);
-
-    // Layout functions.
     std.def_func("box", box_);
     std.def_func("block", block);
-    std.def_func("stack", stack);
-    std.def_func("grid", grid);
-    std.def_func("pad", pad);
-    std.def_func("columns", columns);
     std.def_func("align", align);
+    std.def_func("pad", pad);
     std.def_func("place", place);
     std.def_func("move", move_);
     std.def_func("scale", scale);
     std.def_func("rotate", rotate);
-    std.def_func("image", image);
-    std.def_func("rect", rect);
-    std.def_func("square", square);
-    std.def_func("ellipse", ellipse);
-    std.def_func("circle", circle);
+    std.def_func("stack", stack);
+    std.def_func("grid", grid);
+    std.def_func("columns", columns);
+
+    // Breaks.
+    std.def_func("pagebreak", pagebreak);
+    std.def_func("colbreak", colbreak);
+    std.def_func("parbreak", parbreak);
+    std.def_func("linebreak", linebreak);
 
     // Utility functions.
     std.def_func("assert", assert);
diff --git a/src/library/page.rs b/src/library/page.rs
index a6d489ba..522fd3ac 100644
--- a/src/library/page.rs
+++ b/src/library/page.rs
@@ -4,7 +4,7 @@ use std::fmt::{self, Display, Formatter};
 use std::str::FromStr;
 
 use super::prelude::*;
-use super::{ColumnsNode, PadNode};
+use super::ColumnsNode;
 
 /// Layouts its child onto one or multiple pages.
 #[derive(Clone, PartialEq, Hash)]
@@ -111,7 +111,7 @@ impl PageNode {
         }
 
         // Realize margins with padding node.
-        child = PadNode { child, padding }.pack();
+        child = child.padded(padding);
 
         // Layout the child.
         let expand = size.map(Length::is_finite);
diff --git a/src/library/par.rs b/src/library/par.rs
index 87ad2ebe..38d15097 100644
--- a/src/library/par.rs
+++ b/src/library/par.rs
@@ -29,7 +29,10 @@ impl ParNode {
 
 impl Construct for ParNode {
     fn construct(_: &mut EvalContext, args: &mut Args) -> TypResult<Node> {
-        // Lift to a block so that it doesn't merge with adjacent stuff.
+        // The paragraph constructor is special: It doesn't create a paragraph
+        // since that happens automatically through markup. Instead, it just
+        // lifts the passed body to the block level so that it won't merge with
+        // adjacent stuff and it styles the contained paragraphs.
         Ok(Node::Block(args.expect("body")?))
     }
 }
diff --git a/src/library/text.rs b/src/library/text.rs
index ab5c15c3..d5c87949 100644
--- a/src/library/text.rs
+++ b/src/library/text.rs
@@ -96,10 +96,10 @@ impl TextNode {
 
 impl Construct for TextNode {
     fn construct(_: &mut EvalContext, args: &mut Args) -> TypResult<Node> {
-        // We don't need to do anything more here because the whole point of the
-        // text constructor is to apply the styles and that happens
-        // automatically during class construction.
-        args.expect::<Node>("body")
+        // The text constructor is special: It doesn't create a text node.
+        // Instead, it leaves the passed argument structurally unchanged, but
+        // styles all text in it.
+        args.expect("body")
     }
 }
 
@@ -404,9 +404,7 @@ fn line_impl(args: &mut Args, kind: LineKind) -> TypResult<Value> {
     let extent = args.named("extent")?.unwrap_or_default();
     let body: Node = args.expect("body")?;
     let deco = LineDecoration { kind, stroke, thickness, offset, extent };
-    Ok(Value::Node(
-        body.styled(StyleMap::with(TextNode::LINES, vec![deco])),
-    ))
+    Ok(Value::Node(body.styled(TextNode::LINES, vec![deco])))
 }
 
 /// Defines a line that is positioned over, under or on top of text.