Fabric: Introducing `TreeMutationInstruction`

Summary: The Great Diffing algorithm is coming.

Reviewed By: fkgozali

Differential Revision: D7376528

fbshipit-source-id: bdfef69551980136cfd1717a11ae376d5eef126b

ReactCommon/fabric/uimanager/TreeMutationInstruction.cpp

@@ -0,0 +1,150 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "TreeMutationInstruction.h"
+
+#include <fabric/debug/DebugStringConvertibleItem.h>
+
+namespace facebook {
+namespace react {
+
+const TreeMutationInstruction TreeMutationInstruction::Insert(
+  SharedShadowNode parentNode,
+  SharedShadowNode childNode,
+  int index
+) {
+  assert(parentNode);
+  assert(childNode);
+  assert(index != -1);
+
+  return TreeMutationInstruction(
+    Inserting,
+    parentNode,
+    nullptr,
+    childNode,
+    index
+  );
+}
+
+const TreeMutationInstruction TreeMutationInstruction::Delete(
+  SharedShadowNode parentNode,
+  SharedShadowNode childNode,
+  int index
+) {
+  assert(parentNode);
+  assert(childNode);
+  assert(index != -1);
+
+  return TreeMutationInstruction(
+    Deleting,
+    parentNode,
+    childNode,
+    nullptr,
+    index
+  );
+}
+
+const TreeMutationInstruction TreeMutationInstruction::Update(
+  SharedShadowNode parentNode,
+  SharedShadowNode oldChildNode,
+  SharedShadowNode newChildNode,
+  int index
+) {
+  assert(parentNode);
+  assert(oldChildNode);
+  assert(newChildNode);
+  assert(index != -1);
+
+  return TreeMutationInstruction(
+    Updating,
+    parentNode,
+    oldChildNode,
+    newChildNode,
+    index
+  );
+}
+
+TreeMutationInstruction::TreeMutationInstruction(
+  Type type,
+  SharedShadowNode parentNode,
+  SharedShadowNode oldChildNode,
+  SharedShadowNode newChildNode,
+  int index
+):
+  type_(type),
+  parentNode_(parentNode),
+  oldChildNode_(oldChildNode),
+  newChildNode_(newChildNode),
+  index_(index) {};
+
+#pragma mark - Getters
+
+TreeMutationInstruction::Type TreeMutationInstruction::getType() const {
+  return type_;
+}
+
+SharedShadowNode TreeMutationInstruction::getParentNode() const {
+  assert(parentNode_);
+  return parentNode_;
+}
+
+SharedShadowNode TreeMutationInstruction::getOldChildNode() const {
+  assert(oldChildNode_);
+  return oldChildNode_;
+}
+
+SharedShadowNode TreeMutationInstruction::getNewChildNode() const {
+  assert(newChildNode_);
+  return newChildNode_;
+}
+
+int TreeMutationInstruction::getIndex() const {
+  assert(index_ != -1);
+  return index_;
+}
+
+#pragma mark - DebugStringConvertible
+
+std::string TreeMutationInstruction::getDebugName() const {
+  switch (type_) {
+    case Inserting:
+      return "Insert";
+    case Deleting:
+      return "Delete";
+    case Updating:
+      return "Update";
+  }
+};
+
+SharedDebugStringConvertibleList TreeMutationInstruction::getDebugProps() const {
+  DebugStringConvertibleOptions options = {.maximumDepth = 1, .format = false};
+
+  switch (type_) {
+    case Inserting:
+      return SharedDebugStringConvertibleList {
+        std::make_shared<DebugStringConvertibleItem>("parentNode", parentNode_->getDebugDescription(options)),
+        std::make_shared<DebugStringConvertibleItem>("childNode", newChildNode_->getDebugDescription(options)),
+        std::make_shared<DebugStringConvertibleItem>("index", std::to_string(index_))
+      };
+    case Deleting:
+      return SharedDebugStringConvertibleList {
+        std::make_shared<DebugStringConvertibleItem>("parentNode", parentNode_->getDebugDescription(options)),
+        std::make_shared<DebugStringConvertibleItem>("childNode", oldChildNode_->getDebugDescription(options)),
+        std::make_shared<DebugStringConvertibleItem>("index", std::to_string(index_))
+      };
+    case Updating:
+      return SharedDebugStringConvertibleList {
+        std::make_shared<DebugStringConvertibleItem>("parentNode", parentNode_->getDebugDescription(options)),
+        std::make_shared<DebugStringConvertibleItem>("oldChildNode", oldChildNode_->getDebugDescription(options)),
+        std::make_shared<DebugStringConvertibleItem>("newChildNode", newChildNode_->getDebugDescription(options)),
+        std::make_shared<DebugStringConvertibleItem>("index", std::to_string(index_))
+      };
+  }
+}
+
+} // namespace react
+} // namespace facebook

ReactCommon/fabric/uimanager/TreeMutationInstruction.h

@@ -0,0 +1,109 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * 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 <vector>
+
+#include <fabric/core/ShadowNode.h>
+#include <fabric/debug/DebugStringConvertible.h>
+
+namespace facebook {
+namespace react {
+
+class TreeMutationInstruction;
+
+using TreeMutationInstructionList = std::vector<TreeMutationInstruction>;
+
+/*
+ * Describes single native views tree mutation instruction which may contain
+ * pointers to an old shadow node, a new shadow node, a parent shadow node and
+ * final index of inserted or updated node.
+ * The relationship between native view instances and shadow node instances is
+ * defined by `tag` value.
+ */
+class TreeMutationInstruction:
+  public DebugStringConvertible {
+public:
+
+#pragma mark - Designated Initializers
+
+  /*
+   * Creates and returns an *Insert* instruction with following semantic:
+   *   1. Create a native view for the shadow node if needed;
+   *   2. Unmount the native view from a previous superview if needed;
+   *   3. Mount the native view to the new superview.
+   */
+  static const TreeMutationInstruction Insert(
+    SharedShadowNode parentNode,
+    SharedShadowNode childNode,
+    int index
+  );
+
+  /*
+   * Creates and returns a *Delete* instruction with following semantic:
+   *   1. Unmount the native view from a previous superview if needed;
+   *   2. Destroy (or return to a recycle pool) the native view.
+   */
+  static const TreeMutationInstruction Delete(
+    SharedShadowNode parentNode,
+    SharedShadowNode childNode,
+    int index
+  );
+  
+  /*
+   * Creates and returns an *Update* instruction with following semantic:
+   *   1. Update the presentation of a native view based on the new shadow node;
+   *   2. The exact set of changes are not specified but might contain
+   *      new props and/or new layout (or might be empty).
+   */
+  static const TreeMutationInstruction Update(
+    SharedShadowNode parentNode,
+    SharedShadowNode oldChildNode,
+    SharedShadowNode newChildNode,
+    int index
+  );
+
+#pragma mark - Type
+
+  enum Type {
+    Inserting,
+    Deleting,
+    Updating
+  };
+
+#pragma mark - Getters
+
+  Type getType() const;
+  SharedShadowNode getParentNode() const;
+  SharedShadowNode getOldChildNode() const;
+  SharedShadowNode getNewChildNode() const;
+  int getIndex() const;
+
+#pragma mark - DebugStringConvertible
+
+  std::string getDebugName() const override;
+  SharedDebugStringConvertibleList getDebugProps() const override;
+
+private:
+  TreeMutationInstruction(
+    Type type,
+    SharedShadowNode parentNode,
+    SharedShadowNode oldChildNode,
+    SharedShadowNode newChildNode,
+    int index
+  );
+
+  Type type_ {Inserting};
+  SharedShadowNode parentNode_ {nullptr};
+  SharedShadowNode oldChildNode_ {nullptr};
+  SharedShadowNode newChildNode_ {nullptr};
+  int index_ {-1};
+};
+
+} // namespace react
+} // namespace facebook