Fix #33: Mixing patterns w/ and w/o prematchers

CHANGELOG.rst

@@ -7,6 +7,11 @@
 Changelog
 =========
 
+2.0.1 (2023-XX-XX)
+------------------
+
+- Fix exception when mixing patterns with prematchers and without prematchers.
+
 2.0.0 (2023-03-08)
 ------------------
 

src/multiregex/__init__.py

@@ -83,10 +83,13 @@ def __init__(
         patterns = self._generate_missing_prematchers(patterns)
         self.patterns = [pattern for pattern, _ in patterns]
         self.prematchers = dict(patterns)
+        enumerated_patterns = list(enumerate(patterns))
         self.patterns_without_prematchers = {
-            pattern for pattern, prematchers in patterns if not prematchers
+            (idx, pattern)
+            for idx, (pattern, prematchers) in enumerated_patterns
+            if not prematchers
         }
-        self.automaton = self._make_automaton(patterns)
+        self.automaton = self._make_automaton(enumerated_patterns)
 
         self.count_prematcher_false_positives = count_prematcher_false_positives
         if count_prematcher_false_positives:
@@ -142,10 +145,10 @@ def _generate_missing_prematchers(self, patterns):
         return patterns
 
     @staticmethod
-    def _make_automaton(patterns):
+    def _make_automaton(enumerated_patterns):
         """Create the pyahocorasick automaton."""
         pattern_candidates_by_prematchers = collections.defaultdict(set)
-        for pattern_idx, (pattern, prematchers) in enumerate(patterns):
+        for pattern_idx, (pattern, prematchers) in enumerated_patterns:
             for prematcher in prematchers:
                 # `pattern_idx` is used for keeping patterns in order, see `get_pattern_candidates`.
                 pattern_candidates_by_prematchers[prematcher].add(

tests/test_multiregex.py

@@ -38,11 +38,13 @@ def test_search_match_fullmatch():
 
 
 def test_ordered():
-    patterns = [re.compile(c) for c in "abcdef"]
+    patterns = [
+        (re.compile(c), None if i % 2 == 0 else []) for i, c in enumerate("abcdef")
+    ]  # type: ignore
     random.shuffle(patterns)
     matcher = RegexMatcher(patterns)
-    matches = matcher.search("abcdef")
-    assert [p for p, _ in matches] == patterns
+    matches = matcher.search("abcdefg")
+    assert [p for p, _ in matches] == [p for p, _ in patterns]
 
 
 @pytest.mark.parametrize(