Prototyping custom receiver types for self-typing and more

ArrayList.java

package root.sub;

import java.util.Arrays;
import java.util.Iterator;
import javax.annotation.Generated;
import root.List;

public class ArrayList<T> implements List<T> {
	protected @SuppressWarnings("unchecked") T[] array = (T[]) new Object[0];

	@Generated(value = { "javac" })
	public @Override <THIS extends List<T2>, T2 extends CharSequence> String join_List(THIS thiz, CharSequence delim) {
		return join_ArrayList((ArrayList<T2>) thiz, delim);
	}
	@Generated(value = { "consumer" })
	public <THIS extends ArrayList<T2>, T2 extends Object & CharSequence> String join_ArrayList(THIS thiz, CharSequence delim) {
		assert this == thiz;
		T2[] array2 = thiz.array;
		if(array2.length == 0) {
			return "";
		}
		if(array2.length == 1) {
			return array2[0].toString();
		}
		int length = delim.length() * (array2.length - 1);
		for(int i = 0; i < array2.length; i++) {
			CharSequence t2 = array2[i];
			length += t2.length();
		}
		StringBuilder bu = new StringBuilder(length);
		bu.append(array2[0]);
		for(int i = 1; i < array2.length; i++) {
			bu.append(delim);
			bu.append(array2[i]);
		}
		return bu.toString();
	}
	@Generated(value = { "javac" })
	public @Override <THIS extends List<T2>, T2 extends List<T3>, T3> T2 flatten_List(THIS thiz) {
		return flatten_ArrayList((ArrayList<T2>) thiz);
	}
	@Generated(value = { "consumer" })
	public <THIS extends ArrayList<T2>, T2 extends List<T3>, T3> T2 flatten_ArrayList(THIS thiz) {
		assert this == thiz;
		Object[] array2 = thiz.array;
		if(array2.length == 0) {
			return null;
		}
		int length = 0;
		for(int i = 0; i < array2.length; i++) {
			if(array2[i].getClass() == ArrayList.class) {
				ArrayList<?> list = (ArrayList<?>) array2[i];
				length += list.array.length;
			} else {
				return List.super.flatten_List(thiz);
			}
		}
		@SuppressWarnings("unchecked")
		ArrayList<T3> first = (ArrayList<T3>) array2[0];
		int offset = first.array.length;
		first.array = Arrays.copyOf(first.array, length);
		for(int i = 1; i < array2.length; i++) {
			ArrayList<?> src = (ArrayList<?>) array2[i];
			System.arraycopy(src.array, 0, first.array, offset, src.array.length);
			offset += src.array.length;
		}
		@SuppressWarnings("unchecked")
		T2 result = (T2) first;
		return result;
	}
	@Generated(value = { "javac" })
	public @Override <THIS extends List<T>, T2 extends T> THIS addAll_List(THIS thiz, Iterable<T2> iterable) {
		ArrayList<T> thiz2 = addAll_ArrayList((ArrayList<T>) thiz, iterable);
		@SuppressWarnings("unchecked")
		THIS thiz3 = (THIS) thiz2;
		return thiz3;
	}
	@Generated(value = { "javac" })
	public <THIS extends ArrayList<T>, T2 extends T> THIS addAll_ArrayList(THIS thiz, Iterable<T2> iterable) {
		return List.super.addAll_List(thiz, iterable);
	}
	@Generated(value = { "javac" })
	public @Override <THIS extends List<T>> THIS add_List(THIS thiz, T t) {
		ArrayList<T> thiz2 = (ArrayList<T>) thiz;
		@SuppressWarnings("unchecked")
		THIS thiz3 = (THIS) add_ArrayList(thiz2, t);
		return thiz3;
	}
	@Generated(value = { "consumer" })
	public <THIS extends ArrayList<T>> THIS add_ArrayList(THIS thiz, T t) {
		assert this == thiz;
		thiz.array = Arrays.copyOf(thiz.array, thiz.array.length + 1);
		thiz.array[thiz.array.length - 1] = t;
		return thiz;
	}
	@Generated(value = { "consumer" })
	public @Override Iterator<T> iterator() {
		return Arrays.asList(array).iterator();
	}
	@Generated(value = { "consumer" })
	public @Override String toString() {
		return Arrays.toString(array);
	}
	@Generated(value = { "consumer" })
	public @SafeVarargs static <T> ArrayList<T> asList(T... ts) {
		@SuppressWarnings("unchecked")
		T[] ts2 = (T[]) new Object[ts.length];
		System.arraycopy(ts, 0, ts2, 0, ts.length);
		ArrayList<T> a = new ArrayList<>();
		a.array = ts2;
		return a;
	}
	public static void main(String[] args) {
		version1("11");
		version2("12");
		version3("13");
		version4("14");
		version5("15");
		version6("16");
		version7("17");
		version8("18");
	}
	private static void version1(String name) {
		ArrayList<String> a1 = asList("1", "2");
		ArrayList<String> a2 = asList("4", "5");
		ArrayList<ArrayList<String>> b = asList(a1.add_List(a1, "3"), a2.add_ArrayList(a2, "6"));
		ArrayList<ArrayList<String>> c = b.addAll_ArrayList(b, asList(asList("7"), asList(name)));
		ArrayList<String> d = c.flatten_ArrayList(c);
		String e = d.join_ArrayList(d, "-");
		System.out.print(d);
		System.out.println(e);
	}
	private static void version2(String name) {
		List<String> a1 = asList("1", "2");
		ArrayList<String> a2 = asList("4", "5");
		ArrayList<List<String>> b = asList(a1.add_List(a1, "3"), a2.add_List(a2, "6"));
		ArrayList<List<String>> c = b.addAll_List(b, asList(asList("7"), asList(name)));
		List<String> d = c.flatten_ArrayList(c);
		String e = d.join_List(d, "");
		System.out.print(d);
		System.out.println(e);
	}
	private static void version3(String name) {
		ArrayList<String> a1 = asList("1", "2");
		List<String> a2 = asList("4", "5");
		ArrayList<List<String>> b = asList(a1.add_ArrayList(a1, "3"), a2.add_List(a2, "6"));
		ArrayList<List<String>> c = b.addAll_ArrayList(b, asList(asList("7"), asList(name)));
		List<String> d = c.flatten_List(c);
		String e = d.join_List(d, "-");
		System.out.print(d);
		System.out.println(e);
	}
	private static void version4(String name) {
		List<String> a1 = asList("1", "2");
		List<String> a2 = asList("4", "5");
		ArrayList<List<String>> b = asList(a1.add_List(a1, "3"), a2.add_List(a2, "6"));
		ArrayList<List<String>> c = b.addAll_List(b, asList(asList("7"), asList(name)));
		List<String> d = c.flatten_List(c);
		String e = d.join_List(d, "");
		System.out.print(d);
		System.out.println(e);
	}
	private static void version5(String name) {
		ArrayList<String> a1 = asList("1", "2");
		ArrayList<String> a2 = asList("4", "5");
		List<ArrayList<String>> b = asList(a1.add_ArrayList(a1, "3"), a2.add_List(a2, "6"));
		List<ArrayList<String>> c = b.addAll_List(b, asList(asList("7"), asList(name)));
		ArrayList<String> d = c.flatten_List(c);
		String e = d.join_List(d, "-");
		System.out.print(d);
		System.out.println(e);
	}
	private static void version6(String name) {
		List<String> a1 = asList("1", "2");
		ArrayList<String> a2 = asList("4", "5");
		List<List<String>> b = asList(a1.add_List(a1, "3"), a2.add_ArrayList(a2, "6"));
		List<List<String>> c = b.addAll_List(b, asList(asList("7"), asList(name)));
		List<String> d = c.flatten_List(c);
		String e = d.join_List(d, "");
		System.out.print(d);
		System.out.println(e);
	}
	private static void version7(String name) {
		ArrayList<String> a1 = asList("1", "2");
		List<String> a2 = asList("4", "5");
		List<List<String>> b = asList(a1.add_List(a1, "3"), a2.add_List(a2, "6"));
		List<List<String>> c = b.addAll_List(b, asList(asList("7"), asList(name)));
		List<String> d = c.flatten_List(c);
		String e = d.join_List(d, "-");
		System.out.print(d);
		System.out.println(e);
	}
	private static void version8(String name) {
		List<String> a1 = asList("1", "2");
		List<String> a2 = asList("4", "5");
		List<List<String>> b = asList(a1.add_List(a1, "3"), a2.add_List(a2, "6"));
		List<List<String>> c = b.addAll_List(b, asList(asList("7"), asList(name)));
		List<String> d = c.flatten_List(c);
		String e = d.join_List(d, "");
		System.out.print(d);
		System.out.println(e);
	}
}

List.java

package root;

import javax.annotation.Generated;

public interface List<T> extends Iterable<T> {
	@Generated(value = { "consumer" })
	default <THIS extends List<T2>, T2 extends CharSequence> String join_List(THIS thiz, CharSequence delim) {
		assert this == thiz;
		return String.join(delim, thiz);
	}
	@Generated(value = { "consumer" })
	default <THIS extends List<T3>, T3 extends List<T2>, T2> T3 flatten_List(THIS thiz) {
		assert this == thiz;
		T3 result = null;
		for(T3 items : thiz) {
			result = result == null ? items : result.addAll_List(result, items);
		}
		return result;
	}
	@Generated(value = { "consumer" })
	default <THIS extends List<T>, T2 extends T> THIS addAll_List(THIS thiz, Iterable<T2> iterable) {
		assert this == thiz;
		THIS result = thiz;
		for(T2 item : iterable) {
			result = result.add_List(result, item);
		}
		return result;
	}
	@Generated(value = { "consumer" })
	<THIS extends List<T>> THIS add_List(THIS thiz, T t);
}