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node_modules/react-native/ReactCommon/react/renderer/mounting/MountingTransaction.h

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+/*
+ * 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/mounting/ShadowViewMutation.h>
+#include <react/renderer/telemetry/SurfaceTelemetry.h>
+#include <react/renderer/telemetry/TransactionTelemetry.h>
+
+namespace facebook::react {
+
+/*
+ * Encapsulates all artifacts of `ShadowTree` commit (or a series of them),
+ * particularly list of mutations and meta-data associated with the commit.
+ * Movable and copyable, but moving is strongly encouraged.
+ * Beware: A moved-from object of this type has unspecified value and accessing
+ * that is UB (Undefined Behaviour).
+ */
+class MountingTransaction final {
+ public:
+  /*
+   * A Number (or revision) grows continuously starting from `1`. Value `0`
+   * represents the state before the very first transaction happens.
+   */
+  using Number = int64_t;
+
+  /*
+   * Copying a list of `ShadowViewMutation` is expensive, so the constructor
+   * accepts it as rvalue reference to discourage copying.
+   */
+  MountingTransaction(
+      SurfaceId surfaceId,
+      Number number,
+      ShadowViewMutationList &&mutations,
+      TransactionTelemetry telemetry);
+
+  /*
+   * Copy semantic.
+   * Copying of MountingTransaction is expensive, so copy-constructor is
+   * explicit and copy-assignment is deleted to prevent accidental copying.
+   */
+  explicit MountingTransaction(const MountingTransaction &mountingTransaction) = default;
+  MountingTransaction &operator=(const MountingTransaction &other) = delete;
+
+  /*
+   * Move semantic.
+   */
+  MountingTransaction(MountingTransaction &&mountingTransaction) noexcept = default;
+  MountingTransaction &operator=(MountingTransaction &&other) = default;
+
+  /*
+   * Returns a list of mutations that represent the transaction. The list can be
+   * empty (theoretically).
+   */
+  const ShadowViewMutationList &getMutations() const &;
+  ShadowViewMutationList getMutations() &&;
+
+  /*
+   * Returns telemetry associated with this transaction.
+   */
+  TransactionTelemetry &getTelemetry() const;
+
+  /*
+   * Returns the id of the surface that the transaction belongs to.
+   */
+  SurfaceId getSurfaceId() const;
+
+  /*
+   * Returns a sequential number of the particular transaction.
+   */
+  Number getNumber() const;
+
+  /*
+   * Merges the given transaction in the current transaction, so they
+   * can be executed atomatically as a single transaction.
+   *
+   * This is required for Android UI, which needs to separately apply
+   * each ShadowTree mutation due to differences in props representation.
+   */
+  void mergeWith(MountingTransaction &&transaction);
+
+ private:
+  SurfaceId surfaceId_;
+  Number number_;
+  ShadowViewMutationList mutations_;
+  mutable TransactionTelemetry telemetry_;
+};
+
+} // namespace facebook::react