From b39823a4f9d13a5d313ca665e06884b587bceb9a Mon Sep 17 00:00:00 2001
From: Jonas Maier <jonas@x77.dev>
Date: Wed, 3 Jun 2026 20:17:25 +0200
Subject: regex: explicitly return an error for unsupported non-greedy
 repetitions

---
 src/parse/mod.rs       |  7 +++++++
 src/parse/regex/mod.rs | 39 ++++++++++++++++++++-------------------
 2 files changed, 27 insertions(+), 19 deletions(-)

(limited to 'src')

diff --git a/src/parse/mod.rs b/src/parse/mod.rs
index f61baf9..10ea979 100644
--- a/src/parse/mod.rs
+++ b/src/parse/mod.rs
@@ -1186,6 +1186,13 @@ pub enum ParseError {
     NotAWhile,
 
     ExpectedKeyword(Keyword),
+
+    NotYetImplemented(NotImplementedKind),
+}
+
+#[derive(Debug, PartialEq)]
+pub enum NotImplementedKind {
+    NonGreedyRegexRepetition,
 }
 
 type Result<T> = std::result::Result<T, ParseError>;
diff --git a/src/parse/regex/mod.rs b/src/parse/regex/mod.rs
index f35d3f2..72e11da 100644
--- a/src/parse/regex/mod.rs
+++ b/src/parse/regex/mod.rs
@@ -1,4 +1,4 @@
-use crate::parse::OtherHighlights;
+use crate::parse::{NotImplementedKind, OtherHighlights};
 
 use super::{Parse, ParseError, Result};
 
@@ -98,26 +98,27 @@ fn parse_rep(s: &mut super::Cursor<'_>) -> Result<Pattern> {
 
     let begin = s.loc();
 
-    match s.peek() {
-        b'*' => {
-            s.adv();
-            s.highlight_from(begin, OtherHighlights::RegexSymbol);
-            Ok(Pattern::Rep(Box::new(atom), 0, None))
-        }
-        b'+' => {
-            s.adv();
-            s.highlight_from(begin, OtherHighlights::RegexSymbol);
-            Ok(Pattern::Rep(Box::new(atom), 1, None))
-        }
-        b'?' => {
-            s.adv();
-            s.highlight_from(begin, OtherHighlights::RegexSymbol);
-            Ok(Pattern::Rep(Box::new(atom), 0, Some(1)))
+    let rep = match s.peek() {
+        b'*' => Some((0, None)),
+        b'+' => Some((1, None)),
+        b'?' => Some((0, Some(1))),
+        _ => None,
+    };
+
+    if let Some((min_rep, max_rep)) = rep {
+        s.adv();
+        s.highlight_from(begin, OtherHighlights::RegexSymbol);
+
+        if s.has() && s.peek() == b'?' {
+            return Err(ParseError::NotYetImplemented(
+                NotImplementedKind::NonGreedyRegexRepetition,
+            ));
         }
-        _ => Ok(atom),
-    }
 
-    // TODO: non-greedy
+        Ok(Pattern::Rep(Box::new(atom), min_rep, max_rep))
+    } else {
+        Ok(atom)
+    }
 }
 
 const SYMBOLS: &[u8] = b"{}[]()*+-?|.\\ ";
-- 
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