/
hash.dart
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/
hash.dart
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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/// Generates a hash code for multiple [objects].
int hashObjects(Iterable objects) =>
_finish(objects.fold(0, (h, i) => _combine(h, i.hashCode)));
/// Generates a hash code for two objects.
int hash2(a, b) => _finish(_combine(_combine(0, a.hashCode), b.hashCode));
/// Generates a hash code for three objects.
int hash3(a, b, c) => _finish(
_combine(_combine(_combine(0, a.hashCode), b.hashCode), c.hashCode));
/// Generates a hash code for four objects.
int hash4(a, b, c, d) => _finish(_combine(
_combine(_combine(_combine(0, a.hashCode), b.hashCode), c.hashCode),
d.hashCode));
// Jenkins hash functions
int _combine(int hash, int value) {
hash = 0x1fffffff & (hash + value);
hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
return hash ^ (hash >> 6);
}
int _finish(int hash) {
hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
hash = hash ^ (hash >> 11);
return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
}