72 lines
2.7 KiB
C++
72 lines
2.7 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <react/renderer/core/ShadowNode.h>
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#include <react/renderer/debug/flags.h>
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#include <react/renderer/mounting/ShadowViewMutation.h>
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#include <deque>
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namespace facebook {
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namespace react {
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enum class ReparentMode { Flatten, Unflatten };
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/**
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* During differ, we need to keep some `ShadowViewNodePair`s in memory.
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* Some `ShadowViewNodePair`s are referenced from std::vectors returned
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* by `sliceChildShadowNodeViewPairsV2`; some are referenced in TinyMaps
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* for view (un)flattening especially; and it is not always clear which
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* std::vectors will outlive which TinyMaps, and vice-versa, so it doesn't
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* make sense for the std::vector or TinyMap to own any `ShadowViewNodePair`s.
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*
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* Thus, we introduce the concept of a scope.
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*
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* For the duration of some operation, we keep a ViewNodePairScope around, such
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* that: (1) the ViewNodePairScope keeps each
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* ShadowViewNodePair alive, (2) we have a stable pointer value that we can
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* use to reference each ShadowViewNodePair (not guaranteed with std::vector,
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* for example, which may have to resize and move values around).
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*
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* As long as we only manipulate the data-structure with push_back, std::deque
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* both (1) ensures that pointers into the data-structure are never invalidated,
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* and (2) tries to efficiently allocate storage such that as many objects as
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* possible are close in memory, but does not guarantee adjacency.
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*/
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using ViewNodePairScope = std::deque<ShadowViewNodePair>;
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/*
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* Calculates a list of view mutations which describes how the old
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* `ShadowTree` can be transformed to the new one.
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* The list of mutations might be and might not be optimal.
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*/
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ShadowViewMutation::List calculateShadowViewMutations(
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ShadowNode const &oldRootShadowNode,
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ShadowNode const &newRootShadowNode);
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/**
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* Generates a list of `ShadowViewNodePair`s that represents a layer of a
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* flattened view hierarchy. The V2 version preserves nodes even if they do
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* not form views and their children are flattened.
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*/
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ShadowViewNodePair::NonOwningList sliceChildShadowNodeViewPairsV2(
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ShadowNode const &shadowNode,
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ViewNodePairScope &viewNodePairScope,
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bool allowFlattened = false,
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Point layoutOffset = {0, 0});
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/*
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* Generates a list of `ShadowViewNodePair`s that represents a layer of a
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* flattened view hierarchy. This is *only* used by unit tests currently.
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*/
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ShadowViewNodePair::OwningList sliceChildShadowNodeViewPairsLegacy(
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ShadowNode const &shadowNode);
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} // namespace react
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} // namespace facebook
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