[fix] do highlight replacement at once

Highlights all search queries in search result in one go.

Fixes the case where search query contains word from highlight HTML code,
which causes broken HTML to appear in search results.

Closes searxng#3057

searx/webutils.py

@@ -290,10 +290,8 @@ def highlight_content(content, query):
         if len(qs) > 0:
             queries.extend(re.findall(regex_highlight_cjk(qs), content, flags=re.I | re.U))
     if len(queries) > 0:
-        for q in set(queries):
-            content = re.sub(
-                regex_highlight_cjk(q), f'<span class="highlight">{q}</span>'.replace('\\', r'\\'), content
-            )
+        regex = re.compile("|".join(map(regex_highlight_cjk, queries)))
+        return regex.sub(lambda match: f'<span class="highlight">{match.group(0)}</span>'.replace('\\', r'\\'), content)
     return content
 
 

tests/unit/test_webutils.py

@@ -57,6 +57,11 @@ def test_highlight_content(self):
                     ]
                 ),
             ),
+            (
+                'a class',
+                'a string with class.',
+                '<span class="highlight">a</span> string with <span class="highlight">class</span>.',
+            ),
         )
         for query, content, expected in data:
             self.assertEqual(webutils.highlight_content(content, query), expected)