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V2.java
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199 lines (173 loc) · 4.98 KB
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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.List;
import fj.data.NonEmptyList;
import fj.data.Stream;
import java.util.Iterator;
/**
* A vector-2.
*/
public final class V2<A> implements Iterable<A> {
private final P2<A, A> inner;
private V2(final P2<A, A> inner) {
this.inner = inner;
}
/**
* Creates a vector-2 from a homogeneous product-2.
*
* @param p The product-2 from which to create a vector.
* @return A new vector-2.
*/
public static <A> V2<A> p(final P2<A, A> p) {
return new V2<>(p);
}
/**
* Returns the first element of this vector.
*
* @return the first element of this vector.
*/
public A _1() {
return inner._1();
}
/**
* Returns the second element of this vector.
*
* @return the second element of this vector.
*/
public A _2() {
return inner._2();
}
/**
* 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 <A> F<V2<A>, A> __1() {
return V2::_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 <A> F<V2<A>, A> __2() {
return V2::_2;
}
/**
* Returns an iterator for the elements of this vector.
*
* @return an iterator for the elements of this vector.
*/
public Iterator<A> iterator() {
return toStream().iterator();
}
/**
* Returns a homogeneous product-2 equivalent to this vector.
*
* @return a homogeneous product-2 equivalent to this vector.
*/
public P2<A, A> p() {
return inner;
}
/**
* Returns a nonempty list with the elements of this vector.
*
* @return a nonempty list with the elements of this vector.
*/
public NonEmptyList<A> toNonEmptyList() {
return NonEmptyList.nel(_1(), List.single(_2()));
}
/**
* Returns a stream of the elements of this vector.
*
* @return a stream of the elements of this vector.
*/
public Stream<A> toStream() {
return Stream.cons(_1(), () -> Stream.single(_2()));
}
/**
* Returns a function that transforms a vector-2 to a stream of its elements.
*
* @return a function that transforms a vector-2 to a stream of its elements.
*/
public static <A> F<V2<A>, Stream<A>> toStream_() {
return V2::toStream;
}
/**
* Returns a function that transforms a vector-2 to the equivalent product-2.
*
* @return a function that transforms a vector-2 to the equivalent product-2.
*/
public static <A> F<V2<A>, P2<A, A>> p_() {
return V2::p;
}
/**
* Returns an array with the elements of this vector.
*
* @return an array with the elements of this vector.
*/
@SuppressWarnings("unchecked")
public Array<A> toArray() {
return Array.array(_1(), _2());
}
/**
* 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 <B> V2<B> map(final F<A, B> f) {
return p(inner.split(f, 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 <B> V2<B> apply(final V2<F<A, B>> vf) {
return p(inner.split(vf._1(), vf._2()));
}
/**
* 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 <B, C> V2<C> zipWith(final F<A, F<B, C>> f, final V2<B> 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 <B> V2<P2<A, B>> zip(final V2<B> bs) {
final F<A, F<B, P2<A, B>>> __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 V2<V2<A>> vzip(final V2<A> bs) {
final F2<A, A, V2<A>> __2 = V.v2();
return zipWith(curry(__2), bs);
}
/**
* Return the first element of this vector as a product-1.
*
* @return the first element of this vector as a product-1.
*/
public P1<A> head() {
return P.lazy(V2.this::_1);
}
}