internal_links: Parse "/is/mentioned" internal links.

As of now, we don't have generic for the "is" operator, but it will be a
easy refactor once we do.

Fixes #250.

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

lib/model/internal_link.dart

@@ -154,6 +154,7 @@ Narrow? _interpretNarrowSegments(List<String> segments, PerAccountStore store) {
   ApiNarrowStream? streamElement;
   ApiNarrowTopic? topicElement;
   ApiNarrowDm? dmElement;
+  ApiNarrowIsMentioned? isMentionedElement;
 
   for (var i = 0; i < segments.length; i += 2) {
     final (operator, negated) = _parseOperator(segments[i]);
@@ -181,6 +182,10 @@ Narrow? _interpretNarrowSegments(List<String> segments, PerAccountStore store) {
         if (dmIds == null) return null;
         dmElement = ApiNarrowDm(dmIds, negated: negated);
 
+      case _NarrowOperator.is_:
+        if (isMentionedElement != null) return null;
+        if (operand == 'mentioned') isMentionedElement = ApiNarrowIsMentioned();
+
       case _NarrowOperator.near: // TODO(#82): support for near
       case _NarrowOperator.with_: // TODO(#683): support for with
         continue;
@@ -190,7 +195,10 @@ Narrow? _interpretNarrowSegments(List<String> segments, PerAccountStore store) {
     }
   }
 
-  if (dmElement != null) {
+  if (isMentionedElement != null) {
+    if (streamElement != null || topicElement != null || dmElement != null) return null;
+    return const MentionsNarrow();
+  } else if (dmElement != null) {
     if (streamElement != null || topicElement != null) return null;
     return DmNarrow.withUsers(dmElement.operand, selfUserId: store.selfUserId);
   } else if (streamElement != null) {
@@ -212,6 +220,9 @@ enum _NarrowOperator {
   // cannot use `with` as it is a reserved keyword in Dart
   @JsonValue('with')
   with_,
+  // cannot use `is` as it is a reserved keyword in Dart
+  @JsonValue('is')
+  is_,
   pmWith,
   stream,
   channel,

lib/model/internal_link.g.dart

@@ -221,6 +221,20 @@ void main() {
       testExpectedNarrows(testCases, streams: streams);
     });
 
+    group('"/#narrow/is/mentioned returns expected MentionsNarrow', () {
+      final testCases = [
+        ('/#narrow/is/mentioned',                                     const MentionsNarrow()),
+        ('/#narrow/is/mentioned/near/1',                              const MentionsNarrow()),
+        ('/#narrow/is/mentioned/with/2',                              const MentionsNarrow()),
+        ('/#narrow/channel/7-test-here/is/mentioned',                 null),
+        ('/#narrow/channel/check/topic/test/is/mentioned',            null),
+        ('/#narrow/topic/test/is/mentioned',                          null),
+        ('/#narrow/dm/17327-Chris-Bobbe-(Test-Account)/is/mentioned', null),
+        ('/#narrow/-is/mentioned',                                    null),
+      ];
+      testExpectedNarrows(testCases, streams: streams);
+    });
+
     group('unexpected link shapes are rejected', () {
       final testCases = [
         ('/#narrow/stream/name/topic/',           null), // missing operand