Visitor Class — react Architecture

Source Code

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/CollectReactiveIdentifiers.ts lines 20–63

class Visitor extends ReactiveFunctionVisitor<Set<IdentifierId>> {
  /*
   * Visitors don't visit lvalues as places by default, but we want to visit all places to
   * check for reactivity
   */
  override visitLValue(
    id: InstructionId,
    lvalue: Place,
    state: Set<IdentifierId>,
  ): void {
    this.visitPlace(id, lvalue, state);
  }

  /*
   * This visitor only infers data dependencies and does not account for control dependencies
   * where a variable may be assigned a different value based on some conditional, eg via two
   * different paths of an if statement.
   */
  override visitPlace(
    _id: InstructionId,
    place: Place,
    state: Set<IdentifierId>,
  ): void {
    if (place.reactive) {
      state.add(place.identifier.id);
    }
  }

  override visitPrunedScope(
    scopeBlock: PrunedReactiveScopeBlock,
    state: Set<IdentifierId>,
  ): void {
    this.traversePrunedScope(scopeBlock, state);

    for (const [id, decl] of scopeBlock.scope.declarations) {
      if (
        !isPrimitiveType(decl.identifier) &&
        !isStableRefType(decl.identifier, state)
      ) {
        state.add(id);
      }
    }
  }
}