amis-rpc-design/node_modules/react-native/ReactCommon/react/renderer/mounting/Differentiator.h

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2023-10-07 19:42:30 +08:00
/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#pragma once
#include <react/renderer/core/ShadowNode.h>
#include <react/renderer/debug/flags.h>
#include <react/renderer/mounting/ShadowViewMutation.h>
#include <deque>
namespace facebook {
namespace react {
enum class ReparentMode { Flatten, Unflatten };
/**
* During differ, we need to keep some `ShadowViewNodePair`s in memory.
* Some `ShadowViewNodePair`s are referenced from std::vectors returned
* by `sliceChildShadowNodeViewPairsV2`; some are referenced in TinyMaps
* for view (un)flattening especially; and it is not always clear which
* std::vectors will outlive which TinyMaps, and vice-versa, so it doesn't
* make sense for the std::vector or TinyMap to own any `ShadowViewNodePair`s.
*
* Thus, we introduce the concept of a scope.
*
* For the duration of some operation, we keep a ViewNodePairScope around, such
* that: (1) the ViewNodePairScope keeps each
* ShadowViewNodePair alive, (2) we have a stable pointer value that we can
* use to reference each ShadowViewNodePair (not guaranteed with std::vector,
* for example, which may have to resize and move values around).
*
* As long as we only manipulate the data-structure with push_back, std::deque
* both (1) ensures that pointers into the data-structure are never invalidated,
* and (2) tries to efficiently allocate storage such that as many objects as
* possible are close in memory, but does not guarantee adjacency.
*/
using ViewNodePairScope = std::deque<ShadowViewNodePair>;
/*
* Calculates a list of view mutations which describes how the old
* `ShadowTree` can be transformed to the new one.
* The list of mutations might be and might not be optimal.
*/
ShadowViewMutation::List calculateShadowViewMutations(
ShadowNode const &oldRootShadowNode,
ShadowNode const &newRootShadowNode);
/**
* Generates a list of `ShadowViewNodePair`s that represents a layer of a
* flattened view hierarchy. The V2 version preserves nodes even if they do
* not form views and their children are flattened.
*/
ShadowViewNodePair::NonOwningList sliceChildShadowNodeViewPairsV2(
ShadowNode const &shadowNode,
ViewNodePairScope &viewNodePairScope,
bool allowFlattened = false,
Point layoutOffset = {0, 0});
/*
* Generates a list of `ShadowViewNodePair`s that represents a layer of a
* flattened view hierarchy. This is *only* used by unit tests currently.
*/
ShadowViewNodePair::OwningList sliceChildShadowNodeViewPairsLegacy(
ShadowNode const &shadowNode);
} // namespace react
} // namespace facebook