Fix enum parsing and allow zero in numberings

Fixes #353.

3 files changed, 5 insertions, 9 deletions

diff --git a/src/eval/library.rs b/src/eval/library.rs
index 85d5647b..5b0ff8e6 100644
--- a/src/eval/library.rs
+++ b/src/eval/library.rs
@@ -74,7 +74,7 @@ pub struct LangItems {
     /// An item in a bullet list: `- ...`.
     pub list_item: fn(body: Content) -> Content,
     /// An item in an enumeration (numbered list): `+ ...` or `1. ...`.
-    pub enum_item: fn(number: Option<NonZeroUsize>, body: Content) -> Content,
+    pub enum_item: fn(number: Option<usize>, body: Content) -> Content,
     /// An item in a term list: `/ Term: Details`.
     pub term_item: fn(term: Content, description: Content) -> Content,
     /// A mathematical equation: `$x$`, `$ x^2 $`.
diff --git a/src/syntax/ast.rs b/src/syntax/ast.rs
index bd8fa230..b064da88 100644
--- a/src/syntax/ast.rs
+++ b/src/syntax/ast.rs
@@ -681,7 +681,7 @@ node! {
 
 impl EnumItem {
     /// The explicit numbering, if any: `23.`.
-    pub fn number(&self) -> Option<NonZeroUsize> {
+    pub fn number(&self) -> Option<usize> {
         self.0.children().find_map(|node| match node.kind() {
             SyntaxKind::EnumMarker => node.text().trim_end_matches('.').parse().ok(),
             _ => Option::None,
diff --git a/src/syntax/lexer.rs b/src/syntax/lexer.rs
index 90a10f52..c46fa37b 100644
--- a/src/syntax/lexer.rs
+++ b/src/syntax/lexer.rs
@@ -170,7 +170,6 @@ impl Lexer<'_> {
             '`' => self.raw(),
             'h' if self.s.eat_if("ttp://") => self.link(),
             'h' if self.s.eat_if("ttps://") => self.link(),
-            '0'..='9' => self.numbering(start),
             '<' if self.s.at(is_id_continue) => self.label(),
             '@' => self.ref_marker(),
 
@@ -200,6 +199,7 @@ impl Lexer<'_> {
             '-' if self.space_or_end() => SyntaxKind::ListMarker,
             '+' if self.space_or_end() => SyntaxKind::EnumMarker,
             '/' if self.space_or_end() => SyntaxKind::TermMarker,
+            '0'..='9' => self.numbering(start),
 
             _ => self.text(),
         }
@@ -284,12 +284,8 @@ impl Lexer<'_> {
         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::<usize>() {
-                if number == 0 {
-                    return self.error("must be positive");
-                }
-
+        if self.s.eat_if('.') && self.space_or_end() {
+            if read.parse::<usize>().is_ok() {
                 return SyntaxKind::EnumMarker;
             }
         }