Multi-part numbering patterns

5 files changed, 20 insertions, 7 deletions

diff --git a/src/model/library.rs b/src/model/library.rs
index eee69675..c890fef1 100644
--- a/src/model/library.rs
+++ b/src/model/library.rs
@@ -60,7 +60,7 @@ pub struct LangItems {
     /// An item in an unordered list: `- ...`.
     pub list_item: fn(body: Content) -> Content,
     /// An item in an enumeration (ordered list): `+ ...` or `1. ...`.
-    pub enum_item: fn(number: Option<usize>, body: Content) -> Content,
+    pub enum_item: fn(number: Option<NonZeroUsize>, body: Content) -> Content,
     /// An item in a description list: `/ Term: Details`.
     pub desc_item: fn(term: Content, body: Content) -> Content,
     /// A mathematical formula: `$x$`, `$ x^2 $`.
diff --git a/src/syntax/ast.rs b/src/syntax/ast.rs
index 81ddd596..3c60acbb 100644
--- a/src/syntax/ast.rs
+++ b/src/syntax/ast.rs
@@ -365,7 +365,7 @@ node! {
 
 impl EnumItem {
     /// The explicit numbering, if any: `23.`.
-    pub fn number(&self) -> Option<usize> {
+    pub fn number(&self) -> Option<NonZeroUsize> {
         self.0.children().find_map(|node| match node.kind() {
             SyntaxKind::EnumNumbering(num) => Some(*num),
             _ => None,
diff --git a/src/syntax/kind.rs b/src/syntax/kind.rs
index b7ee6a79..a7425d70 100644
--- a/src/syntax/kind.rs
+++ b/src/syntax/kind.rs
@@ -1,4 +1,5 @@
 use std::hash::{Hash, Hasher};
+use std::num::NonZeroUsize;
 use std::sync::Arc;
 
 use crate::geom::{AbsUnit, AngleUnit};
@@ -164,7 +165,7 @@ pub enum SyntaxKind {
     /// An item in an enumeration (ordered list): `+ ...` or `1. ...`.
     EnumItem,
     /// An explicit enumeration numbering: `23.`.
-    EnumNumbering(usize),
+    EnumNumbering(NonZeroUsize),
     /// An item in a description list: `/ Term: Details`.
     DescItem,
     /// A mathematical formula: `$x$`, `$ x^2 $`.
diff --git a/src/syntax/tokens.rs b/src/syntax/tokens.rs
index e0ef2fa1..e7015bb2 100644
--- a/src/syntax/tokens.rs
+++ b/src/syntax/tokens.rs
@@ -1,3 +1,4 @@
+use std::num::NonZeroUsize;
 use std::sync::Arc;
 
 use unicode_xid::UnicodeXID;
@@ -395,8 +396,11 @@ impl<'s> Tokens<'s> {
         self.s.eat_while(char::is_ascii_digit);
         let read = self.s.from(start);
         if self.s.eat_if('.') {
-            if let Ok(number) = read.parse() {
-                return SyntaxKind::EnumNumbering(number);
+            if let Ok(number) = read.parse::<usize>() {
+                return match NonZeroUsize::new(number) {
+                    Some(number) => SyntaxKind::EnumNumbering(number),
+                    None => SyntaxKind::Error(ErrorPos::Full, "must be positive".into()),
+                };
             }
         }
 
@@ -933,8 +937,8 @@ mod tests {
         t!(Markup["a "]: r"a--" => Text("a"), Shorthand('\u{2013}'));
         t!(Markup["a1/"]: "- "  => Minus, Space(0));
         t!(Markup[" "]: "+"     => Plus);
-        t!(Markup[" "]: "1."    => EnumNumbering(1));
-        t!(Markup[" "]: "1.a"   => EnumNumbering(1), Text("a"));
+        t!(Markup[" "]: "1."    => EnumNumbering(NonZeroUsize::new(1).unwrap()));
+        t!(Markup[" "]: "1.a"   => EnumNumbering(NonZeroUsize::new(1).unwrap()), Text("a"));
         t!(Markup[" /"]: "a1."  => Text("a1."));
     }
 
diff --git a/src/util/eco.rs b/src/util/eco.rs
index 5a4d7629..8f519504 100644
--- a/src/util/eco.rs
+++ b/src/util/eco.rs
@@ -368,6 +368,14 @@ impl FromIterator<Self> for EcoString {
     }
 }
 
+impl Extend<char> for EcoString {
+    fn extend<T: IntoIterator<Item = char>>(&mut self, iter: T) {
+        for c in iter {
+            self.push(c);
+        }
+    }
+}
+
 impl From<EcoString> for String {
     fn from(s: EcoString) -> Self {
         match s.0 {