1 files changed, 102 insertions, 0 deletions
diff --git a/src/library/list.rs b/src/library/list.rs
new file mode 100644
index 00000000..74f0abe8
--- /dev/null
+++ b/src/library/list.rs
@@ -0,0 +1,102 @@
+use std::hash::Hash;
+
+use super::prelude::*;
+use super::{GridNode, TextNode, TrackSizing};
+
+/// An unordered or ordered list.
+#[derive(Debug, Hash)]
+pub struct ListNode<L> {
+    /// The node that produces the item's body.
+    pub child: PackedNode,
+    /// The list labelling style -- unordered or ordered.
+    pub labelling: L,
+}
+
+#[properties]
+impl<L: Labelling> ListNode<L> {
+    /// The indentation of each item's label.
+    pub const LABEL_INDENT: Linear = Relative::new(0.0).into();
+    /// The space between the label and the body of each item.
+    pub const BODY_INDENT: Linear = Relative::new(0.5).into();
+}
+
+impl<L: Labelling> Construct for ListNode<L> {
+    fn construct(_: &mut EvalContext, args: &mut Args) -> TypResult<Node> {
+        Ok(args
+            .all()
+            .map(|node: Node| {
+                Node::block(Self {
+                    child: node.into_block(),
+                    labelling: L::default(),
+                })
+            })
+            .sum())
+    }
+}
+
+impl<L: Labelling> Set for ListNode<L> {
+    fn set(styles: &mut Styles, args: &mut Args) -> TypResult<()> {
+        styles.set_opt(Self::LABEL_INDENT, args.named("label-indent")?);
+        styles.set_opt(Self::BODY_INDENT, args.named("body-indent")?);
+        Ok(())
+    }
+}
+
+impl<L: Labelling> Layout for ListNode<L> {
+    fn layout(
+        &self,
+        ctx: &mut LayoutContext,
+        regions: &Regions,
+    ) -> Vec<Constrained<Rc<Frame>>> {
+        let em = ctx.styles.get(TextNode::SIZE).abs;
+        let label_indent = ctx.styles.get(Self::LABEL_INDENT).resolve(em);
+        let body_indent = ctx.styles.get(Self::BODY_INDENT).resolve(em);
+
+        let columns = vec![
+            TrackSizing::Linear(label_indent.into()),
+            TrackSizing::Auto,
+            TrackSizing::Linear(body_indent.into()),
+            TrackSizing::Auto,
+        ];
+
+        let children = vec![
+            PackedNode::default(),
+            Node::Text(self.labelling.label()).into_block(),
+            PackedNode::default(),
+            self.child.clone(),
+        ];
+
+        GridNode {
+            tracks: Spec::new(columns, vec![]),
+            gutter: Spec::default(),
+            children,
+        }
+        .layout(ctx, regions)
+    }
+}
+
+/// How to label a list.
+pub trait Labelling: Debug + Default + Hash + 'static {
+    /// Return the item's label.
+    fn label(&self) -> EcoString;
+}
+
+/// Unordered list labelling style.
+#[derive(Debug, Default, Hash)]
+pub struct Unordered;
+
+impl Labelling for Unordered {
+    fn label(&self) -> EcoString {
+        '•'.into()
+    }
+}
+
+/// Ordered list labelling style.
+#[derive(Debug, Default, Hash)]
+pub struct Ordered(pub Option<usize>);
+
+impl Labelling for Ordered {
+    fn label(&self) -> EcoString {
+        format_eco!("{}.", self.0.unwrap_or(1))
+    }
+}