Remove look-up optimizations in "CountBy"/"ScanBy" (#855)

morelinq · Oct 26, 2022 · af98ba4 · af98ba4
1 parent 212be62
commit af98ba4
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Showing 2 changed files with 2 additions and 25 deletions.
diff --git a/MoreLinq/CountBy.cs b/MoreLinq/CountBy.cs
@@ -82,19 +82,12 @@ void Loop(IEqualityComparer<TKey> cmp)
 
                     keys = new List<TKey>();
                     counts = new List<int>();
-                    (bool, TKey) prevKey = default;
-                    var index = 0;
 
                     foreach (var item in source)
                     {
                         var key = keySelector(item);
 
-                        if (// key same as the previous? then re-use the index
-                            prevKey is (true, {} pk)
-                                && cmp.GetHashCode(pk) == cmp.GetHashCode(key)
-                                && cmp.Equals(pk, key)
-                            // otherwise try & find index of the key
-                            || dic.TryGetValue(key, out index))
+                        if (dic.TryGetValue(key, out var index))
                         {
                             counts[index]++;
                         }
@@ -105,8 +98,6 @@ prevKey is (true, {} pk)
                             keys.Add(key);
                             counts.Add(1);
                         }
-
-                        prevKey = (true, key);
                     }
                 }
             }

diff --git a/MoreLinq/ScanBy.cs b/MoreLinq/ScanBy.cs
@@ -91,27 +91,13 @@ IEnumerable<KeyValuePair<TKey, TState>> _(IEqualityComparer<TKey> comparer)
             {
                 var stateByKey = new Collections.Dictionary<TKey, TState>(comparer);
 
-                (bool, TKey, TState) prev = default;
-
                 foreach (var item in source)
                 {
                     var key = keySelector(item);
-
-                    var state = // key same as the previous? then re-use the state
-                                prev is (true, {} pk, {} ps)
-                                && comparer.GetHashCode(pk) == comparer.GetHashCode(key)
-                                && comparer.Equals(pk, key) ? ps
-                              : // otherwise try & find state of the key
-                                stateByKey.TryGetValue(key, out var ns) ? ns
-                              : seedSelector(key);
-
+                    var state = stateByKey.TryGetValue(key, out var s) ? s : seedSelector(key);
                     state = accumulator(state, key, item);
-
                     stateByKey[key] = state;
-
                     yield return new KeyValuePair<TKey, TState>(key, state);
-
-                    prev = (true, key, state);
                 }
             }
         }