Add an additional MMR "Max Rank 5" metric to the output of the completion_metrics.dart

Change-Id: I00ff65853eaef85bd33d76e930d7ba1d39783a14
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/138882
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Jaime Wren <jwren@google.com>

Author: jwren

pkg/analysis_server/test/services/completion/dart/keyword_contributor_test.dart

@@ -1008,7 +1008,7 @@ class C {
   }
 
   Future<void> test_constructor_param_prefix() async {
-    addTestSource('class A { A(^) {}}');
+    addTestSource('class A { A(t^) {}}');
     await computeSuggestions();
     assertSuggestKeywords(constructorParameter);
   }

pkg/analysis_server/test/tool/completion_metrics/metrics_util_test.dart

@@ -46,7 +46,7 @@ void main() {
       var mrrc = MeanReciprocalRankComputer();
       expect(mrrc.rankCount, equals(0));
       expect(mrrc.ranks, isEmpty);
-      expect(mrrc.mrr, equals(0));
+      expect(mrrc.getMRR(), equals(0));
     });
 
     test('clear', () {
@@ -69,7 +69,7 @@ void main() {
       mrrc.addRank(3);
       expect(mrrc.rankCount, equals(5));
       expect(mrrc.ranks, equals([3, 3, 3, 3, 3]));
-      expect(mrrc.mrr, doubleEquals(1 / 3));
+      expect(mrrc.getMRR(), doubleEquals(1 / 3));
     });
 
     test('mmr- example', () {
@@ -79,7 +79,17 @@ void main() {
       mrrc.addRank(1);
       expect(mrrc.rankCount, equals(3));
       expect(mrrc.ranks, equals([3, 2, 1]));
-      expect(mrrc.mrr, doubleEquals(11 / 18));
+      expect(mrrc.getMRR(), doubleEquals(11 / 18));
+    });
+
+    test('mmr- max rank', () {
+      var mrrc = MeanReciprocalRankComputer();
+      mrrc.addRank(3);
+      mrrc.addRank(2);
+      mrrc.addRank(1);
+      expect(mrrc.rankCount, equals(3));
+      expect(mrrc.ranks, equals([3, 2, 1]));
+      expect(mrrc.getMRR(2), doubleEquals(1 / 2));
     });
   });
 

pkg/analysis_server/tool/completion_metrics/metrics_util.dart

@@ -65,14 +65,21 @@ class MeanReciprocalRankComputer {
   final List<int> ranks = [];
   MeanReciprocalRankComputer();
 
-  double get mrr {
-    if (ranks.isEmpty) {
+  double getMRR([int maxRank = 0]) {
+    if (ranks.isEmpty || maxRank < 0) {
       return 0;
     }
-
     double sum = 0;
     ranks.forEach((rank) {
-      sum += rank != 0 ? (1 / rank) : 0;
+      if (maxRank == 0) {
+        if (rank != 0) {
+          sum += 1 / rank;
+        }
+      } else {
+        if (rank != 0 && rank <= maxRank) {
+          sum += 1 / rank;
+        }
+      }
     });
     return sum / rankCount;
   }
@@ -86,9 +93,15 @@ class MeanReciprocalRankComputer {
   void clear() => ranks.clear();
 
   void printMean() {
-    var mrrVal = mrr;
-    print('Mean Reciprocal Rank    = ${mrrVal.toStringAsFixed(5)}');
-    print('Harmonic Mean (inverse) = ${(1 / mrrVal).toStringAsFixed(2)}');
+    var mrrVal = getMRR();
+    print(
+        'Mean Reciprocal Rank                  = ${mrrVal.toStringAsFixed(6)} '
+        '(inverse = ${(1 / mrrVal).toStringAsFixed(3)})');
+
+    var mrrVal5 = getMRR(5);
+    print(
+        'Mean Reciprocal Rank (max rank 5)     = ${mrrVal5.toStringAsFixed(6)} '
+        '(inverse = ${(1 / mrrVal5).toStringAsFixed(3)})');
   }
 }