"Reverting 28184"

sdk/lib/math/jenkins_smi_hash.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-part of dart.math;
-
-/**
- * This is the [Jenkins hash function][1] but using masking to keep
- * values in SMI range.
- *
- * [1]: http://en.wikipedia.org/wiki/Jenkins_hash_function
- *
- * Use:
- * Hash each value with the hash of the previous value, then get the final
- * hash by calling finish.
- *
- *     var hash = 0;
- *     for (var value in values) {
- *       hash = JenkinsSmiHash.combine(hash, value.hashCode);
- *     }
- *     hash = JenkinsSmiHash.finish(hash);
- */
-class _JenkinsSmiHash {
-  // TODO(11617): This class should be optimized and standardized elsewhere.
-
-  static int combine(int hash, int value) {
-    hash = 0x1fffffff & (hash + value);
-    hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
-    return hash ^ (hash >> 6);
-  }
-
-  static int finish(int hash) {
-    hash = 0x1fffffff & (hash + ((0x03ffffff & hash) <<  3));
-    hash = hash ^ (hash >> 11);
-    return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
-  }
-
-  static int hash2(a, b) => finish(combine(combine(0, a), b));
-
-  static int hash4(a, b, c, d) =>
-      finish(combine(combine(combine(combine(0, a), b), c), d));
-}