getProperty() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/HIR/PropagateScopeDependenciesHIR.ts lines 338–384

function getProperty(
  object: Place,
  propertyName: PropertyLiteral,
  optional: boolean,
  temporaries: ReadonlyMap<IdentifierId, ReactiveScopeDependency>,
): ReactiveScopeDependency {
  /*
   * (1) Get the base object either from the temporary sidemap (e.g. a LoadLocal)
   * or a deep copy of an existing property dependency.
   *  Example 1:
   *    $0 = LoadLocal x
   *    $1 = PropertyLoad $0.y
   *  getProperty($0, ...) -> resolvedObject = x, resolvedDependency = null
   *
   *  Example 2:
   *    $0 = LoadLocal x
   *    $1 = PropertyLoad $0.y
   *    $2 = PropertyLoad $1.z
   *  getProperty($1, ...) -> resolvedObject = null, resolvedDependency = x.y
   *
   *  Example 3:
   *    $0 = Call(...)
   *    $1 = PropertyLoad $0.y
   *  getProperty($0, ...) -> resolvedObject = null, resolvedDependency = null
   */
  const resolvedDependency = temporaries.get(object.identifier.id);

  /**
   * (2) Push the last PropertyLoad
   * TODO(mofeiZ): understand optional chaining
   */
  let property: ReactiveScopeDependency;
  if (resolvedDependency == null) {
    property = {
      identifier: object.identifier,
      reactive: object.reactive,
      path: [{property: propertyName, optional}],
    };
  } else {
    property = {
      identifier: resolvedDependency.identifier,
      reactive: resolvedDependency.reactive,
      path: [...resolvedDependency.path, {property: propertyName, optional}],
    };
  }
  return property;
}