ComposableMutator

ComposableMutator.ts

type ComposableMutatorFn<T> = (t: T) => T;
export class ComposableMutator<T> {
  constructor(private mutators: ComposableMutatorFn<T>[], private data?: T) {
    this.mutators = mutators || [data => data];
  }

  public addMutator(fn: ComposableMutatorFn<T>): ComposableMutator<T> {
    return this.dupe(fn);
  }

  public exec(data?: T): T {
      if (!data && !this.data) {
        throw new Error('No data set in ComposableMutator');
      }
      return this.mutators.reduce((s, factory) => {
        return factory(s);
      }, data || this.data);
  }

  private dupe(fn: ComposableMutatorFn<T>): ComposableMutator<T> {
    return ComposableMutator.for<T>([...this.mutators, fn], this.data);
  }


  static for<T>(mutators?: ComposableMutatorFn<T>[], data?: T) {
    return new ComposableMutator<T>(mutators, data);
  }
}