Using IndexedScore as part of the search pre-filtering. (#8232)

Author: isoos

app/lib/search/mem_index.dart

@@ -113,31 +113,28 @@ class InMemoryPackageIndex {
   }
 
   PackageSearchResult search(ServiceSearchQuery query) {
-    final packages = Set<String>.of(_documentsByName.keys);
+    final packageScores = IndexedScore(_packageNameIndex._packageNames, 1.0);
 
     // filter on package prefix
     if (query.parsedQuery.packagePrefix != null) {
       final String prefix = query.parsedQuery.packagePrefix!.toLowerCase();
-      packages.removeWhere(
-        (package) => !_documentsByName[package]!
-            .package
-            .toLowerCase()
-            .startsWith(prefix),
+      packageScores.retainWhere(
+        (i, _) => _documents[i].packageNameLowerCased.startsWith(prefix),
       );
     }
 
     // filter on tags
     final combinedTagsPredicate =
         query.tagsPredicate.appendPredicate(query.parsedQuery.tagsPredicate);
     if (combinedTagsPredicate.isNotEmpty) {
-      packages.retainWhere((package) => combinedTagsPredicate
-          .matches(_documentsByName[package]!.tagsForLookup));
+      packageScores.retainWhere(
+          (i, _) => combinedTagsPredicate.matches(_documents[i].tagsForLookup));
     }
 
     // filter on dependency
     if (query.parsedQuery.hasAnyDependency) {
-      packages.removeWhere((package) {
-        final doc = _documentsByName[package]!;
+      packageScores.removeWhere((i, _) {
+        final doc = _documents[i];
         if (doc.dependencies.isEmpty) return true;
         for (final dependency in query.parsedQuery.allDependencies) {
           if (!doc.dependencies.containsKey(dependency)) return true;
@@ -152,22 +149,18 @@ class InMemoryPackageIndex {
 
     // filter on points
     if (query.minPoints != null && query.minPoints! > 0) {
-      packages.removeWhere((package) {
-        final doc = _documentsByName[package]!;
-        return doc.grantedPoints < query.minPoints!;
-      });
+      packageScores.removeWhere(
+          (i, _) => _documents[i].grantedPoints < query.minPoints!);
     }
 
     // filter on updatedDuration
     final updatedDuration = query.parsedQuery.updatedDuration;
     if (updatedDuration != null && updatedDuration > Duration.zero) {
       final now = clock.now();
-      packages.removeWhere((package) {
-        final doc = _documentsByName[package]!;
-        final diff = now.difference(doc.updated);
-        return diff > updatedDuration;
-      });
+      packageScores.removeWhere(
+          (i, _) => now.difference(_documents[i].updated) > updatedDuration);
     }
+    final packages = packageScores.toKeySet();
 
     // do text matching
     final parsedQueryText = query.parsedQuery.text;

app/lib/search/search_service.dart

@@ -132,6 +132,8 @@ class PackageDocument {
 
   @JsonKey(includeFromJson: false, includeToJson: false)
   late final Set<String> tagsForLookup = Set.of(tags);
+
+  late final packageNameLowerCased = package.toLowerCase();
 }
 
 /// A reference to an API doc page

app/lib/search/token_index.dart

@@ -214,27 +214,26 @@ class TokenIndex {
   Map<String, double> _scoreDocs(TokenMatch tokenMatch,
       {double weight = 1.0, Set<String>? limitToIds}) {
     // Summarize the scores for the documents.
-    final docScores = List<double>.filled(_length, 0.0);
+    final scores = IndexedScore(_ids);
     for (final token in tokenMatch.tokens) {
       final docWeights = _inverseIds[token]!;
       for (final e in docWeights.entries) {
-        final i = e.key;
-        docScores[i] = math.max(docScores[i], tokenMatch[token]! * e.value);
+        scores.setValueMaxOf(e.key, tokenMatch[token]! * e.value);
       }
     }
 
+    if (limitToIds != null) {
+      scores.retainWhere((_, id) => limitToIds.contains(id));
+    }
     final result = <String, double>{};
     // post-process match weights
     for (var i = 0; i < _length; i++) {
-      final id = _ids[i];
-      final w = docScores[i];
+      final w = scores._values[i];
       if (w <= 0.0) {
         continue;
       }
-      if (limitToIds != null && !limitToIds.contains(id)) {
-        continue;
-      }
-      result[id] = w * weight;
+      final id = _ids[i];
+      result[id] = scores._values[i] * weight;
     }
     return result;
   }
@@ -269,3 +268,53 @@ class TokenIndex {
     return Score.multiply(scores);
   }
 }
+
+/// Mutable score list that can accessed via integer index.
+class IndexedScore {
+  final List<String> _keys;
+  final List<double> _values;
+
+  IndexedScore._(this._keys, this._values);
+
+  factory IndexedScore(List<String> keys, [double value = 0.0]) =>
+      IndexedScore._(keys, List<double>.filled(keys.length, value));
+
+  late final length = _values.length;
+
+  bool isNotPositive(int index) {
+    return _values[index] <= 0.0;
+  }
+
+  void setValueMaxOf(int index, double value) {
+    _values[index] = math.max(_values[index], value);
+  }
+
+  void removeWhere(bool Function(int index, String key) fn) {
+    for (var i = 0; i < length; i++) {
+      if (isNotPositive(i)) continue;
+      if (fn(i, _keys[i])) {
+        _values[i] = 0.0;
+      }
+    }
+  }
+
+  void retainWhere(bool Function(int index, String key) fn) {
+    for (var i = 0; i < length; i++) {
+      if (isNotPositive(i)) continue;
+      if (!fn(i, _keys[i])) {
+        _values[i] = 0.0;
+      }
+    }
+  }
+
+  Set<String> toKeySet() {
+    final set = <String>{};
+    for (var i = 0; i < _values.length; i++) {
+      final v = _values[i];
+      if (v > 0.0) {
+        set.add(_keys[i]);
+      }
+    }
+    return set;
+  }
+}