mockpe1/EmptyList.java at main · LimAiLin/mockpe1 · GitHub

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/**
 * CS2030S PE1 Question 2
 * AY20/21 Semester 2
 *
 * @author A0238768J
 */
class EmptyList<T> implements SourceList<T> {

  @Override
  public T getFirst() {
    return null;
  }

  @Override
  public SourceList<T> getSecond() {
    return null;
  }

  @Override
  public String toString() {
    return "EmptyList";
  }

  // Write your code here

  @Override
  public int length() {
    return 0;
  }

  @Override
  public boolean equals(Object o) {
    if (o instanceof EmptyList<?>) {
      return true;
    } else {
      return false;
    }
  }

  @Override
  public SourceList<T> filter(BooleanCondition cond) {
    return this;
  }

  @Override
  public <U> SourceList<U> map(Transformer<? super T, ? extends U> trans) {
    return new EmptyList<U>();
  }
}