fj.data.vector.V4 Maven / Gradle / Ivy

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package fj.data.vector;

import fj.*;

import static fj.Function.curry;
import static fj.P.p2;
import fj.data.Array;
import fj.data.NonEmptyList;
import fj.data.Stream;

import java.util.Iterator;

/**
 * A vector-4.
 */
public final class V4 implements Iterable {

  private final V3 tail;
  private final P1 head;

  private V4(final P1 head, final V3 tail) {
    this.head = head;
    this.tail = tail;
  }

  @Override
  public final boolean equals(Object other) {
    return Equal.equals0(V4.class, this, other, () -> Equal.v4Equal(Equal.anyEqual()));
  }

  @Override
  public final int hashCode() {
    return Hash.v4Hash(Hash.anyHash()).hash(this);
  }

  /**
   * Creates a vector-4 from a homogeneous product-4.
   *
   * @param p The product-4 from which to create a vector.
   * @return A new vector-4.
   */
  public static  V4 p(final P4 p) {
    return new V4<>(P.lazy(p::_1),
        V3.p(new P3() {
          public A _1() {
            return p._2();
          }

          public A _2() {
            return p._3();
          }

          public A _3() {
            return p._4();
          }
        }));
  }

  /**
   * Creates a vector-4 from a head and a tail.
   *
   * @param head The value to put as the first element of the vector.
   * @param tail The vector representing all but the first element of the new vector.
   * @return The new vector.
   */
  public static  V4 cons(final P1 head, final V3 tail) {
    return new V4<>(head, tail);
  }

  /**
   * Returns the first element of this vector.
   *
   * @return the first element of this vector.
   */
  public A _1() {
    return head._1();
  }

  /**
   * Returns the second element of this vector.
   *
   * @return the second element of this vector.
   */
  public A _2() {
    return tail._1();
  }

  /**
   * Returns the third element of this vector.
   *
   * @return the third element of this vector.
   */
  public A _3() {
    return tail._2();
  }

  /**
   * Returns the fourth element of this vector.
   *
   * @return the fourth element of this vector.
   */
  public A _4() {
    return tail._3();
  }

  /**
   * Returns all but the first element of this vector, as a vector-3.
   *
   * @return all but the first element of this vector, as a vector-3.
   */
  public V3 tail() {
    return tail;
  }

  /**
   * Returns the first element of this vector, as a product-1.
   *
   * @return the first element of this vector, as a product-1.
   */
  public P1 head() {
    return head;
  }

  /**
   * Returns an iterator for the elements of this vector.
   *
   * @return an iterator for the elements of this vector.
   */
  public Iterator iterator() {
    return toStream().iterator();
  }

  /**
   * Returns a homogeneous product-4 equivalent to this vector.
   *
   * @return a homogeneous product-4 equivalent to this vector.
   */
  public P4 p() {
    return new P4() {
      public A _1() {
        return V4.this._1();
      }

      public A _2() {
        return V4.this._2();
      }

      public A _3() {
        return V4.this._3();
      }

      public A _4() {
        return V4.this._4();
      }
    };
  }

  /**
   * Returns a nonempty list with the elements of this vector.
   *
   * @return a nonempty list with the elements of this vector.
   */
  public NonEmptyList toNonEmptyList() {
    return NonEmptyList.nel(_1(), tail.toNonEmptyList().toList());
  }

  /**
   * Returns a stream of the elements of this vector.
   *
   * @return a stream of the elements of this vector.
   */
  public Stream toStream() {
    return Stream.cons(head._1(), tail::toStream);
  }

  /**
   * Returns an array with the elements of this vector.
   *
   * @return an array with the elements of this vector.
   */
  @SuppressWarnings("unchecked")
  public Array toArray() {
    return Array.array(_1(), _2(), _3(), _4());
  }

  /**
   * Maps the given function across this vector.
   *
   * @param f The function to map across this vector.
   * @return A new vector after the given function has been applied to each element.
   */
  public  V4 map(final F f) {
    return new V4<>(head.map(f), tail.map(f));
  }

  /**
   * Performs function application within a vector (applicative functor pattern).
   *
   * @param vf The vector of functions to apply.
   * @return A new vector after zipping the given vector of functions over this vector.
   */
  public  V4 apply(final V4> vf) {
    return new V4<>(head.apply(vf.head()), tail.apply(vf.tail()));
  }

  /**
   * Zips this vector with the given vector using the given function to produce a new vector.
   *
   * @param bs The vector to zip this vector with.
   * @param f  The function to zip this vector and the given vector with.
   * @return A new vector with the results of the function.
   */
  public  V4 zipWith(final F> f, final V4 bs) {
    return bs.apply(map(f));
  }

  /**
   * Zips this vector with the given vector to produce a vector of pairs.
   *
   * @param bs The vector to zip this vector with.
   * @return A new vector with a length the same as the shortest of this vector and the given
   *         vector.
   */
  public  V4> zip(final V4 bs) {
    final F>> __2 = p2();
    return zipWith(__2, bs);
  }

  /**
   * Zips this vector with the given vector to produce a vector of vectors.
   *
   * @param bs The vector to zip this vector with.
   * @return A new vector of vectors.
   */
  public V4> vzip(final V4 bs) {
    final F2> __2 = V.v2();
    return zipWith(curry(__2), bs);
  }

  /**
   * Returns a function that transforms a vector-4 to a stream of its elements.
   *
   * @return a function that transforms a vector-4 to a stream of its elements.
   */
  public static  F, Stream> toStream_() {
    return V4::toStream;
  }

  /**
   * Returns a function that transforms a vector-4 to the equivalent product-4.
   *
   * @return a function that transforms a vector-4 to the equivalent product-4.
   */
  public static  F, P4> p_() {
    return V4::p;
  }

  /**
   * A first-class function to get the first element of a vector.
   *
   * @return a function that gets the first element of a given vector.
   */
  public static  F, A> __1() {
    return V4::_1;
  }

  /**
   * A first-class function to get the second element of a vector.
   *
   * @return a function that gets the second element of a given vector.
   */
  public static  F, A> __2() {
    return V4::_2;
  }

  /**
   * A first-class function to get the third element of a vector.
   *
   * @return a function that gets the third element of a given vector.
   */
  public static  F, A> __3() {
    return V4::_3;
  }

  /**
   * A first-class function to get the fourth element of a vector.
   *
   * @return a function that gets the fourth element of a given vector.
   */
  public static  F, A> __4() {
    return V4::_4;
  }
}