Summary:
@public
Limit child cloning to layout calculation. This also allows for mixing shared and owned children.
Rationale:
We do allow for shared children if the caller manages themselves. The single known use case is React Native.
So far, we have cloned children eagerly whenever child lists are mutated, or layout is run. This was to allow for a quick check of the owner of any first child, assuming that either *all* or *no* child of a node are shared.
For Yoga/Java, we want to get rid of global weak JNI refs, and these are also used to invoke clone callbacks. We can achieve that goal by switching to an alternative approach, passing additional data to the layout pass. This additional data has to be passed to any configured cloning callback. Therefore, it is desirable to **only call cloning functions during the layout pass.**
The obvious solution seems to be to not uphold the invariant of the first child determining shared/owned state of all siblings, and allow for a mix of shared and own children.
Reviewed By: shergin
Differential Revision: D14136223
fbshipit-source-id: 34490cfeeb2170c99d6ed1b9bdcbcedb316813af
Summary: This change drops the year from the copyright headers and the LICENSE file.
Reviewed By: yungsters
Differential Revision: D9727774
fbshipit-source-id: df4fc1e4390733fe774b1a160dd41b4a3d83302a
Summary:
Includes React Native and its dependencies Fresco, Metro, and Yoga. Excludes samples/examples/docs.
find: ^(?:( *)|( *(?:[\*~#]|::))( )? *)?Copyright (?:\(c\) )?(\d{4})\b.+Facebook[\s\S]+?BSD[\s\S]+?(?:this source tree|the same directory)\.$
replace: $1$2$3Copyright (c) $4-present, Facebook, Inc.\n$2\n$1$2$3This source code is licensed under the MIT license found in the\n$1$2$3LICENSE file in the root directory of this source tree.
Reviewed By: TheSavior, yungsters
Differential Revision: D7007050
fbshipit-source-id: 37dd6bf0ffec0923bfc99c260bb330683f35553e
Summary:
This is meant to show a possible route format for a persistent form of Yoga. Where previous layouts can remain intact while still taking advantage of incremental layout by reusing previous subtrees.
```c
YGNodeRef YGNodeClone(const YGNodeRef node);
```
The core of this functionality is a new API to clone an existing node. This makes a new detached node with all the same values as the previous one. Conceptually this makes the original node "frozen" from that point on. It's now immutable. (This is not yet enforced at runtime in this PR but something we should add.)
Since the original is frozen, we reuse the children set from the original node. Their parent pointers still point back to the original tree though.
The cloned node is still mutable. It can have its styles updated, and nodes can be inserted or deleted. If an insertion/deletion happens on a cloned node whose children were reused, it'll first shallow clone its children automatically.
As a convenience I also added an API to clear all children:
```c
void YGNodeRemoveAllChildren(const YGNodeRef node);
```
During insert/delete, or as a result of layout a set of reused children may need to be first cloned. A kind of copy-on-write. When that happens, the host may want to respond. E.g. by updating the `context` such as by cloning any wrapper objects and attaching them to the new node.
```c
typedef void (*YGNodeClonedFunc)(YGNodeRef oldNode,
YGNodeRef newNode,
YGNodeRef parent,
int childIndex);
void YGConfigSetNodeClonedFunc(YGConfigRef config,
YGNodeClonedFunc callback);
```
This PR doesn't change any existing semantics for trees that are not first cloned.
It's possible for a single node to exist in two trees at once and be used by multiple threads. Therefore it's not safe to recursively free a whole tree when you use persistence. To solve this, any user of the library has to manually manage ref counting or tracing GC. E.g. by replicating the tree structure in a wrapper.
In a follow up we could consider moving ref counting into Yoga.
Closes https://github.com/facebook/yoga/pull/636
Reviewed By: emilsjolander
Differential Revision: D5941921
Pulled By: sebmarkbage
fbshipit-source-id: c8e93421824c112d09c4773bed4e3141b6491ccf
