2 files changed, 73 insertions, 13 deletions

diff --git a/src/exec/context.rs b/src/exec/context.rs
index f19f6561..6ba5b25f 100644
--- a/src/exec/context.rs
+++ b/src/exec/context.rs
@@ -3,7 +3,7 @@ use std::rc::Rc;
 
 use fontdock::FontStyle;
 
-use super::{Exec, State};
+use super::{Exec, FontFamily, State};
 use crate::diag::{Diag, DiagSet, Pass};
 use crate::env::Env;
 use crate::eval::TemplateValue;
@@ -74,8 +74,7 @@ impl<'a> ExecContext<'a> {
     /// Set the font to monospace.
     pub fn set_monospace(&mut self) {
         let families = self.state.font.families_mut();
-        families.list.insert(0, "monospace".to_string());
-        families.flatten();
+        families.list.insert(0, FontFamily::Monospace);
     }
 
     /// Push a layout node into the active paragraph.
diff --git a/src/exec/state.rs b/src/exec/state.rs
index f66694fd..0322c437 100644
--- a/src/exec/state.rs
+++ b/src/exec/state.rs
@@ -1,6 +1,7 @@
+use std::fmt::{self, Display, Formatter};
 use std::rc::Rc;
 
-use fontdock::{fallback, FallbackTree, FontStretch, FontStyle, FontVariant, FontWeight};
+use fontdock::{FontStretch, FontStyle, FontVariant, FontWeight};
 
 use crate::color::{Color, RgbaColor};
 use crate::geom::*;
@@ -98,8 +99,8 @@ impl Default for ParState {
 /// Defines font properties.
 #[derive(Debug, Clone, PartialEq)]
 pub struct FontState {
-    /// A tree of font family names and generic class names.
-    pub families: Rc<FallbackTree>,
+    /// A list of font families with generic class definitions.
+    pub families: Rc<FamilyMap>,
     /// The selected font variant.
     pub variant: FontVariant,
     /// The font size.
@@ -122,7 +123,7 @@ pub struct FontState {
 
 impl FontState {
     /// Access the `families` mutably.
-    pub fn families_mut(&mut self) -> &mut FallbackTree {
+    pub fn families_mut(&mut self) -> &mut FamilyMap {
         Rc::make_mut(&mut self.families)
     }
 
@@ -135,12 +136,7 @@ impl FontState {
 impl Default for FontState {
     fn default() -> Self {
         Self {
-            // The default tree of font fallbacks.
-            families: Rc::new(fallback! {
-                list: [],
-                classes: { "monospace"  => ["inconsolata"] },
-                base: ["eb garamond", "twitter color emoji"],
-            }),
+            families: Rc::new(FamilyMap::default()),
             variant: FontVariant {
                 style: FontStyle::Normal,
                 weight: FontWeight::REGULAR,
@@ -156,3 +152,68 @@ impl Default for FontState {
         }
     }
 }
+
+/// Font family definitions.
+#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub struct FamilyMap {
+    /// The user-defined list of font families.
+    pub list: Vec<FontFamily>,
+    /// Definition of serif font families.
+    pub serif: Vec<String>,
+    /// Definition of sans-serif font families.
+    pub sans_serif: Vec<String>,
+    /// Definition of monospace font families used for raw text.
+    pub monospace: Vec<String>,
+    /// Base fonts that are tried if the list has no match.
+    pub base: Vec<String>,
+}
+
+impl FamilyMap {
+    /// Flat iterator over this map's family names.
+    pub fn iter(&self) -> impl Iterator<Item = &str> {
+        self.list
+            .iter()
+            .flat_map(move |family: &FontFamily| {
+                match family {
+                    FontFamily::Named(name) => std::slice::from_ref(name),
+                    FontFamily::Serif => &self.serif,
+                    FontFamily::SansSerif => &self.sans_serif,
+                    FontFamily::Monospace => &self.monospace,
+                }
+            })
+            .chain(&self.base)
+            .map(String::as_str)
+    }
+}
+
+impl Default for FamilyMap {
+    fn default() -> Self {
+        Self {
+            list: vec![FontFamily::Serif],
+            serif: vec!["eb garamond".into()],
+            sans_serif: vec![/* TODO */],
+            monospace: vec!["inconsolata".into()],
+            base: vec!["twitter color emoji".into()],
+        }
+    }
+}
+
+/// A generic or named font family.
+#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub enum FontFamily {
+    Serif,
+    SansSerif,
+    Monospace,
+    Named(String),
+}
+
+impl Display for FontFamily {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Self::Serif => "serif",
+            Self::SansSerif => "sans-serif",
+            Self::Monospace => "monospace",
+            Self::Named(s) => s,
+        })
+    }
+}