任意のオブジェクトを戻り値thisにするパターン化するためのラッパー

Pipeline.java

import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;

public class Pipeline<T, R> {
    private final T value;
    Object lastReturn;

    private Pipeline(T value) {
        this.value = value;
        lastReturn = null;
    }

    public static <T> Pipeline<T, ?> of(T value) {
        return new Pipeline<>(value);
    }

    public R lastReturn() {
        @SuppressWarnings("unchecked")
        R lastReturn = (R)this.lastReturn;
        return lastReturn;
    }

    public Pipeline<T, R> consumeLastReturn(Consumer<? super R> consumer) {
        consumer.accept(lastReturn());
        return this;
    }

    public Pipeline<T, ?> exec(Consumer<? super T> consumer) {
        consumer.accept(value);
        lastReturn = null;
        return this;
    }

    public <V> Pipeline<T, V> exec(Function<? super T, ? extends V> function) {
        lastReturn = function.apply(value);
        @SuppressWarnings("unchecked")
        Pipeline<T, V> ret = (Pipeline<T, V>)this;
        return ret;
    }

    public <Arg1, V> Pipeline<T, V> exec(BiFunction<? super T, ? super Arg1, ? extends V> function, Arg1 arg1) {
        lastReturn = function.apply(value, arg1);
        @SuppressWarnings("unchecked")
        Pipeline<T, V> ret = (Pipeline<T, V>)this;
        return ret;
    }

    public static void main(String[] args) {
        Pipeline.of("Test")
                .exec(String::startsWith, "T").consumeLastReturn(System.out::println)
                .exec(String::length).consumeLastReturn(System.out::println);
    }
}