Revert "Use `values` iterator and `update` in map equality/hash (#718)" (#858)
diff --git a/pkgs/collection/CHANGELOG.md b/pkgs/collection/CHANGELOG.md
index 3231865..30f8c3f 100644
--- a/pkgs/collection/CHANGELOG.md
+++ b/pkgs/collection/CHANGELOG.md
@@ -1,9 +1,8 @@
+
## 1.20.0-wip
- Add `IterableMapEntryExtension` for working on `Map` as a list of pairs, using
`Map.entries`.
-- Optimize equality and hash code for maps by using `update` and a `values`
- iterator to avoid extra lookups.
- Address diagnostics from `strict_top_level_inference`.
## 1.19.1
diff --git a/pkgs/collection/lib/src/equality.dart b/pkgs/collection/lib/src/equality.dart
index 1e2f02a..0e1df23 100644
--- a/pkgs/collection/lib/src/equality.dart
+++ b/pkgs/collection/lib/src/equality.dart
@@ -325,19 +325,16 @@
var length = map1.length;
if (length != map2.length) return false;
Map<_MapEntry, int> equalElementCounts = HashMap();
- var values1 = map1.values.iterator;
for (var key in map1.keys) {
- var value = (values1..moveNext()).current;
- var entry = _MapEntry(this, key, value);
- equalElementCounts.update(entry, _addOne, ifAbsent: _one);
+ var entry = _MapEntry(this, key, map1[key]);
+ var count = equalElementCounts[entry] ?? 0;
+ equalElementCounts[entry] = count + 1;
}
- final values2 = map2.values.iterator;
for (var key in map2.keys) {
- var value = (values2..moveNext()).current;
- var entry = _MapEntry(this, key, value);
- var count = equalElementCounts.update(entry, _subtractOne,
- ifAbsent: _negativeOne);
- if (count < 0) return false;
+ var entry = _MapEntry(this, key, map2[key]);
+ var count = equalElementCounts[entry];
+ if (count == null || count == 0) return false;
+ equalElementCounts[entry] = count - 1;
}
return true;
}
@@ -346,11 +343,9 @@
int hash(Map<K, V>? map) {
if (map == null) return null.hashCode;
var hash = 0;
- var values = map.values.iterator;
for (var key in map.keys) {
- var value = (values..moveNext()).current;
var keyHash = _keyEquality.hash(key);
- var valueHash = _valueEquality.hash(value);
+ var valueHash = _valueEquality.hash(map[key] as V);
hash = (hash + 3 * keyHash + 7 * valueHash) & _hashMask;
}
hash = (hash + (hash << 3)) & _hashMask;
@@ -494,8 +489,3 @@
@override
bool isValidKey(Object? object) => object is String;
}
-
-int _addOne(int i) => i + 1;
-int _subtractOne(int i) => i - 1;
-int _one() => 1;
-int _negativeOne() => -1;
