Konstantin Shcheglov
e97f1bdbf0
This should allow doing partial migration, specifically protocol files, which are imported by other libraries, but are a small library cycle that does not import much outside of it. Change-Id: I904c05d6d5b444ee9a9dbd1f7ada12aabdcc5165 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/193583 Reviewed-by: Brian Wilkerson <brianwilkerson@google.com> Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
39 lines
925 B
Dart
39 lines
925 B
Dart
// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// @dart = 2.9
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/// Returns the given [list] if it is not empty, or `null` otherwise.
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List<E> nullIfEmpty<E>(List<E> list) {
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if (list == null) {
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return null;
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}
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if (list.isEmpty) {
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return null;
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}
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return list;
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}
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/// A container that remembers the last `n` items added to it.
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///
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/// It will never grow larger than [capacity]. It's a LIFO queue - the last item
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/// added will be the first one returned from [items].
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class RecentBuffer<T> {
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final int capacity;
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final List<T> _buffer = [];
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RecentBuffer(this.capacity);
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Iterable<T> get items => _buffer.reversed;
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void add(T item) {
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_buffer.add(item);
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if (_buffer.length > capacity) {
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_buffer.removeAt(0);
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}
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}
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}
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