| 1 | | // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
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| 2 | | // for details. All rights reserved. Use of this source code is governed by a
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| 3 | | // BSD-style license that can be found in the LICENSE file.
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| 4 | |
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| 5 | | library dart_style.src.fast_hash;
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| 6 | |
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| 7 | | /// A mixin for classes with identity equality that need to be frequently
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| 8 | | /// hashed.
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| 9 | | abstract class FastHash {
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| 10 | | static int _nextId = 0;
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| 11 | |
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| 12 | | /// A semi-unique numeric indentifier for the object.
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| 13 | | ///
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| 14 | | /// This is useful for debugging and also speeds up using the object in hash
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| 15 | | /// sets. Ids are *semi*-unique because they may wrap around in long running
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| 16 | | /// processes. Since objects are equal based on their identity, this is
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| 17 | | /// innocuous and prevents ids from growing without bound.
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| 18 | | final int id = _nextId = (_nextId + 1) & 0x0fffffff;
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| 19 | |
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| 20 | 6 | int get hashCode => id;
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| 21 | | }
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