ReactivityMap Class — react Architecture

Source Code

compiler/packages/babel-plugin-react-compiler/src/Inference/InferReactivePlaces.ts lines 368–413

class ReactivityMap {
  hasChanges: boolean = false;
  reactive: Set<IdentifierId> = new Set();

  /**
   * Sets of mutably aliased identifiers — these are the same foundation for determining
   * reactive scopes a few passes later. The actual InferReactiveScopeVariables pass runs
   * after LeaveSSA, which artificially merges mutable ranges in cases such as declarations
   * that are later reassigned. Here we use only the underlying sets of mutably aliased values.
   *
   * Any identifier that has a mapping in this disjoint set will be treated as a stand in for
   * its canonical identifier in all cases, so that any reactivity flowing into one identifier of
   * an alias group will effectively make the whole alias group (all its identifiers) reactive.
   */
  aliasedIdentifiers: DisjointSet<Identifier>;

  constructor(aliasedIdentifiers: DisjointSet<Identifier>) {
    this.aliasedIdentifiers = aliasedIdentifiers;
  }

  isReactive(place: Place): boolean {
    const identifier =
      this.aliasedIdentifiers.find(place.identifier) ?? place.identifier;
    const reactive = this.reactive.has(identifier.id);
    if (reactive) {
      place.reactive = true;
    }
    return reactive;
  }

  markReactive(place: Place): void {
    place.reactive = true;
    const identifier =
      this.aliasedIdentifiers.find(place.identifier) ?? place.identifier;
    if (!this.reactive.has(identifier.id)) {
      this.hasChanges = true;
      this.reactive.add(identifier.id);
    }
  }

  snapshot(): boolean {
    const hasChanges = this.hasChanges;
    this.hasChanges = false;
    return hasChanges;
  }
}