feat: add optional fallback getter when parsing string with shortcodes

* add optional fallback method when parsing string with shortcodes

lib/src/emojis/emoji_parser.dart

@@ -102,16 +102,21 @@ class EmojiParser {
   String toShortcodes([Platform platform = Platform.Default]) {
     return _value.splitMapJoin(Regex.emoji, onMatch: (m) {
       final match = m.group(0)!;
-      return _emojis.getOne(match).shortcodes.wherePlatform(platform) ?? match;
+      return _emojis.getOneOrNull(match)?.shortcodes.wherePlatform(platform) ??
+          match;
     });
   }
 
   /// Converts the emojis in [_value] from shortcode format to Unicode characters.
   /// Shortcodes are the text-based representations of emojis used by some platforms.
   /// Returns a new String with the converted emojis.
-  String fromShortcodes() {
+  String fromShortcodes(
+      {String Function(String unknownShortcode)? onUnknownShortcode}) {
     return _value.splitMapJoin(Regex.shortcode, onMatch: (m) {
-      return _emojis.getOne(m.group(0)!.removeColons()).value;
+      final match = m.group(0)!;
+      return _emojis.getOneOrNull(match.removeColons())?.value ??
+          onUnknownShortcode?.call(match) ??
+          match;
     });
   }
 

test/src/emojis/emoji_parser_test.dart

@@ -257,6 +257,25 @@ void main() {
       expect(value, expected);
     });
 
+    test(
+        'fromShortcodes() returns this raw shortcode when the shortcode does not exist and no replacement method is provided',
+        () {
+      const text = ':man: :this-shortcode-does-not-exist: :woman:';
+      final value = EmojiParser(text).fromShortcodes();
+      const expected = '👨 :this-shortcode-does-not-exist: 👩';
+      expect(value, expected);
+    });
+
+    test(
+        'fromShortcodes() returns this replacement text when shortcode cannot be found and a replacement method is provided',
+        () {
+      const text = ':man: :this-shortcode-does-not-exist: :woman:';
+      final value =
+          EmojiParser(text).fromShortcodes(onUnknownShortcode: (_) => '🤷');
+      const expected = '👨 🤷 👩';
+      expect(value, expected);
+    });
+
     test('get returns list of emojis from given text', () {
       const text = 'text😀text🤦🏾‍♀️text';
       final value = EmojiParser(text).get;