From c73ed9310d8162b71183688de62bf8c1fc8420df Mon Sep 17 00:00:00 2001
From: Jonas Maier <jonas@x77.dev>
Date: Mon, 1 Jun 2026 21:55:53 +0200
Subject: syntax highlighting for regex; syntax highlighting syntax errors

---
 src/parse/regex/mod.rs | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

(limited to 'src/parse/regex')

diff --git a/src/parse/regex/mod.rs b/src/parse/regex/mod.rs
index d5e4cdf..98056cb 100644
--- a/src/parse/regex/mod.rs
+++ b/src/parse/regex/mod.rs
@@ -1,3 +1,5 @@
+use crate::parse::OtherHighlights;
+
 use super::{Parse, ParseError, Result};
 
 mod byte_range;
@@ -16,10 +18,19 @@ pub enum Pattern {
 
 impl Parse for Pattern {
     fn parse(b: &mut super::Cursor<'_>) -> super::Result<Self> {
-        parse_alt(b)
+        let begin = b.loc();
+        let result = parse0(b);
+        if result.is_ok() {
+            b.highlight_from(begin, OtherHighlights::Regex);
+        }
+        result
     }
 }
 
+fn parse0(s: &mut super::Cursor<'_>) -> Result<Pattern> {
+    parse_alt(s)
+}
+
 fn parse_alt(s: &mut super::Cursor<'_>) -> Result<Pattern> {
     let mut seqs = vec![];
     loop {
@@ -27,8 +38,10 @@ fn parse_alt(s: &mut super::Cursor<'_>) -> Result<Pattern> {
         if seq != Pattern::Nothing {
             seqs.push(seq);
         }
+        let begin = s.loc();
         if s.has() && s.peek() == b'|' {
             s.adv();
+            s.highlight_from(begin, OtherHighlights::RegexSymbol);
         } else {
             break;
         }
@@ -70,17 +83,22 @@ fn parse_rep(s: &mut super::Cursor<'_>) -> Result<Pattern> {
         return Ok(atom);
     }
 
+    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)))
         }
         _ => Ok(atom),
@@ -99,21 +117,26 @@ fn parse_atom(s: &mut super::Cursor<'_>) -> Result<Pattern> {
         return Ok(Pattern::Nothing);
     }
 
+    let begin = s.loc();
+
     match s.peek() {
         b'[' => {
             s.adv();
+            s.highlight_from(begin, OtherHighlights::RegexSymbol);
             let mut ranges = Vec::new();
             loop {
                 if !s.has() {
                     return Err(ParseError::Eof);
                 }
 
+                let begin = s.loc();
                 let tok = s.adv();
 
                 if tok == b']' {
                     if ranges.is_empty() {
                         todo!("error handling for empty alternative list");
                     }
+                    s.highlight_from(begin, OtherHighlights::RegexSymbol);
                     return Ok(Pattern::Alt(ranges));
                 }
 
@@ -121,8 +144,10 @@ fn parse_atom(s: &mut super::Cursor<'_>) -> Result<Pattern> {
                     return Err(ParseError::Unknown(tok));
                 }
 
+                let begin = s.loc();
                 if s.has() && s.peek() == b'-' {
                     s.adv();
+                    s.highlight_from(begin, OtherHighlights::RegexSymbol);
 
                     if !s.has() {
                         return Err(ParseError::Eof);
@@ -141,17 +166,21 @@ fn parse_atom(s: &mut super::Cursor<'_>) -> Result<Pattern> {
         }
         b'(' => {
             s.adv();
-            let inner = Pattern::parse(s)?;
+            s.highlight_from(begin, OtherHighlights::RegexSymbol);
+            let inner = parse0(s)?;
             if !s.has() {
                 return Err(ParseError::Eof);
             }
+            let begin = s.loc();
             if s.adv() != b')' {
                 return Err(ParseError::Expected(')'));
             }
+            s.highlight_from(begin, OtherHighlights::RegexSymbol);
             Ok(inner)
         }
         b'.' => {
             s.adv();
+            s.highlight_from(begin, OtherHighlights::RegexSymbol);
             Ok(Pattern::Range(0, 127))
         }
         x if is_symbol(x) => Ok(Pattern::Nothing),
-- 
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