Navigation extension point.

pkg/analysis_server/lib/src/collections.dart

Index: pkg/analysis_server/lib/src/collections.dart
diff --git a/pkg/analysis_server/lib/src/collections.dart b/pkg/analysis_server/lib/src/collections.dart
index 8ab3da82284b89201485a2db7bd03c04f5a4ea17..1a1ba38e53540225abe11ab5c5807b38e3294213 100644
--- a/pkg/analysis_server/lib/src/collections.dart
+++ b/pkg/analysis_server/lib/src/collections.dart
@@ -28,3 +28,20 @@ List nullIfEmpty(List list) {
   }
   return list;
 }
+
+/// A pair of values.
+class Pair<E, F> {
+  final E first;
+  final F last;
+
+  Pair(this.first, this.last);
+
+  int get hashCode => first.hashCode ^ last.hashCode;
+
+  bool operator ==(other) {
+    if (other is! Pair) return false;
+    return other.first == first && other.last == last;
+  }
+
+  String toString() => '($first, $last)';
+}