Remove assertion that threw when any matcher had empty pattern

kaboc · Dec 23, 2023 · b9a057f · b9a057f
1 parent 06271e7
commit b9a057f
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Showing 2 changed files with 39 additions and 21 deletions.
diff --git a/lib/src/parser.dart b/lib/src/parser.dart
@@ -37,16 +37,21 @@ class Parser {
     _matcherGroupRanges.clear();
 
     var groupIndexStart = 2;
+    final patterns = <String>[];
+
     for (var i = 0; i < matchers.length; i++) {
-      assert(
-        matchers[i].pattern.isNotEmpty,
-        'All matchers must have a non-empty pattern.',
-      );
+      final groupName = '$_kMatcherGroupPrefix$i';
+      _matcherGroupNames.add(groupName);
 
-      _matcherGroupNames.add('$_kMatcherGroupPrefix$i');
+      var pattern = matchers[i].pattern;
+      if (pattern.isEmpty) {
+        // Expression that does not match anything.
+        pattern = '(?!)';
+      }
+      patterns.add('(?<$groupName>$pattern)');
 
       final regExp = RegExp(
-        '${matchers[i].pattern}|.*',
+        '$pattern|.*',
         multiLine: multiLine,
         caseSensitive: caseSensitive,
         unicode: unicode,
@@ -57,14 +62,10 @@ class Parser {
       _matcherGroupRanges.add([
         for (var i = 0; i < groupCount; i++) groupIndexStart + i,
       ]);
-
       groupIndexStart += groupCount + 1;
     }
 
-    _pattern = {
-      for (var i = 0; i < matchers.length; i++)
-        '(?<${_matcherGroupNames[i]}>${matchers[i].pattern})',
-    }.join('|');
+    _pattern = patterns.join('|');
   }
 
   List<TextElement> parse(String text, {required bool onlyMatches}) {

diff --git a/test/matchers/matcher_test.dart b/test/matchers/matcher_test.dart
@@ -49,17 +49,34 @@ void main() {
       );
     });
 
-    test('Having matcher containing empty pattern throws AssertionError', () {
-      expect(
-        () => TextParser(matchers: const [EmailMatcher(), PatternMatcher('')]),
-        throwsA(
-          isA<AssertionError>().having(
-            (e) => e.message,
-            'message',
-            contains('must have a non-empty pattern'),
-          ),
-        ),
+    test('correctly parsed with matchers containing empty pattern', () async {
+      final parser = TextParser(
+        matchers: const [
+          PatternMatcher('(bbb)'),
+          PatternMatcher(''),
+          PatternMatcher('(ddd)'),
+        ],
       );
+      final elements = await parser.parse('aaabbbcccdddeee');
+
+      expect(elements, hasLength(5));
+      expect(elements[0], const TextElement('aaa'));
+      expect(elements[0].matcherType, TextMatcher);
+      expect(elements[0].matcherIndex, null);
+      expect(elements[1].text, 'bbb');
+      expect(elements[1].matcherType, PatternMatcher);
+      expect(elements[1].matcherIndex, 0);
+      expect(elements[1].groups, ['bbb']);
+      expect(elements[2].text, 'ccc');
+      expect(elements[2].matcherType, TextMatcher);
+      expect(elements[2].matcherIndex, null);
+      expect(elements[3].text, 'ddd');
+      expect(elements[3].matcherType, PatternMatcher);
+      expect(elements[3].matcherIndex, 2);
+      expect(elements[3].groups, ['ddd']);
+      expect(elements[4].text, 'eee');
+      expect(elements[4].matcherType, TextMatcher);
+      expect(elements[4].matcherIndex, null);
     });
   });
 }