e08c3c3bdc
```dart expect(x, moreOrLessEquals(0.0)); ``` ...for those cases where `x` might be 1e-11 or whatever. Also, be more resilient when dumping the tree from inside the test framework. Also, add an assert that helped me debug something the other day.
62 lines
1.9 KiB
Dart
62 lines
1.9 KiB
Dart
// Copyright 2016 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/foundation.dart';
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import 'package:flutter/widgets.dart';
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/// Provides an iterable that efficiently returns all the elements
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/// rooted at the given element. See [CachingIterable] for details.
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///
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/// This method must be called again if the tree changes. You cannot
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/// call this function once, then reuse the iterable after having
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/// changed the state of the tree, because the iterable returned by
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/// this function caches the results and only walks the tree once.
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///
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/// The same applies to any iterable obtained indirectly through this
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/// one, for example the results of calling `where` on this iterable
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/// are also cached.
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Iterable<Element> collectAllElementsFrom(Element rootElement, {
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@required bool skipOffstage
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}) {
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return new CachingIterable<Element>(new _DepthFirstChildIterator(rootElement, skipOffstage));
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}
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class _DepthFirstChildIterator implements Iterator<Element> {
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_DepthFirstChildIterator(Element rootElement, bool skipOffstage)
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: skipOffstage = skipOffstage,
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_stack = _reverseChildrenOf(rootElement, skipOffstage).toList();
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final bool skipOffstage;
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Element _current;
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final List<Element> _stack;
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@override
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Element get current => _current;
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@override
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bool moveNext() {
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if (_stack.isEmpty)
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return false;
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_current = _stack.removeLast();
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// Stack children in reverse order to traverse first branch first
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_stack.addAll(_reverseChildrenOf(_current, skipOffstage));
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return true;
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}
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static Iterable<Element> _reverseChildrenOf(Element element, bool skipOffstage) {
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assert(element != null);
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final List<Element> children = <Element>[];
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if (skipOffstage) {
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element.visitChildrenForSemantics(children.add);
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} else {
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element.visitChildren(children.add);
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}
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return children.reversed;
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}
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}
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