added 99 bottles or beer

99bottles/Bottles.java

@@ -0,0 +1,197 @@
+public class Bottles {
+	@FunctionalInterface
+	static private interface Action {
+		void execute();
+	}
+	@FunctionalInterface
+	static private interface Consumer<T> {
+		void take(T t);
+	}
+
+	static private class NumberWrapper {
+		public Number number;
+
+		public NumberWrapper(Number n) {
+			number = n;
+		} 
+	}
+	
+	static private class CompareResult {
+		private Number r1;
+		private Number r2;
+
+		public CompareResult(Number r1, Number r2) {
+			this.r1 = r1;
+			this.r2 = r2;
+		}
+
+		public void executeIfEqual(Action action) {
+			r1.executeIfZero(() -> {
+				r2.executeIfZero(action);
+			});
+		}
+
+		public void executeIfGreaterOrEqual(Action action) {
+			r2.executeIfZero(action);
+		}
+
+		public void executeIfLessOrEqual(Action action) {
+			r1.executeIfZero(action);
+		}
+
+		public void executeIfGreater(Action action) {
+			r2.executeIfZero(() -> {
+				r1.executeIfNotZero(action);
+			});
+		}
+		public void executeIfLess(Action action) {
+			r1.executeIfZero(() -> {
+				r2.executeIfNotZero(action);
+			});
+		}
+	}
+
+	static private class Number {
+		private Number predecessor;
+
+		public Number(Number pre) {
+			predecessor = pre;
+		}
+
+		public Number clone() {
+			return new Number(predecessor);
+		}
+
+		public static Number succ(Number pre) {
+			return new Number(pre);
+		}
+
+		public static Number zero() {
+			return new Zero();
+		}
+
+		public static Number one() {
+			return succ(zero());
+		}
+
+		public static Number two() {
+			return succ(one());
+		}
+
+		public Number pre() {
+			return predecessor;
+		}
+
+		public static Number add(Number n1, Number n2) {
+			NumberWrapper wrapper = new NumberWrapper(zero());
+
+			n1.forEach((n) -> {
+				wrapper.number = succ(wrapper.number);
+			});
+
+			n2.forEach((n) -> {
+				wrapper.number = succ(wrapper.number);
+			});
+
+			return wrapper.number;
+		}
+
+		public static Number multiply(Number n1, Number n2) {
+			NumberWrapper wrapper = new NumberWrapper(zero());
+
+			n1.forEach((n) -> {
+				wrapper.number = add(wrapper.number, n2); 
+			});
+
+			return wrapper.number;
+		}
+
+		public int value() {
+			return predecessor.value() + 1;
+		}
+		
+		public void executeIfZero(Action action) {
+		}
+
+		public void executeIfNotZero(Action action) {
+			action.execute();
+		}
+
+		public void forEach(Consumer<Number> consumer) {
+			executeIfNotZero(() -> {
+				consumer.take(this);
+				predecessor.forEach(consumer);
+			});
+		}
+
+		public static Number subtract(Number n1, Number n2) {
+			NumberWrapper wrapper = new NumberWrapper(n1.clone());
+
+			n2.forEach((n) -> {
+				wrapper.number = wrapper.number.pre();
+			});
+
+			return wrapper.number;
+		}
+
+		public CompareResult compare(Number compare) {
+			return new CompareResult(subtract(this, compare), subtract(compare, this));
+		}
+
+		public String toString() {
+			return String.valueOf(value());
+		}
+	}
+
+	static private class Zero extends Number {
+		public Zero() {
+			super(null);
+		}
+
+		@Override
+		public Number clone() {
+			return new Zero();
+		}
+
+		@Override
+		public int value() {
+			return 0;
+		}
+
+		@Override
+		public void executeIfZero(Action action) {
+			action.execute();
+		}
+
+		@Override
+		public void executeIfNotZero(Action action) {
+		}
+	
+		@Override
+		public Number pre() {
+			return this;
+		}
+	}
+
+
+
+	public static void main(String[] args) {
+		Number one = Number.one();
+		Number five = Number.add(Number.add(Number.two(), Number.two()), one);
+		Number ten = Number.multiply(five, Number.two());
+		Number hundred = Number.multiply(ten, ten);
+		Number nintynine = hundred.pre();
+
+		nintynine.forEach((n) -> {
+			CompareResult cr = n.compare(one);
+			cr.executeIfGreater(() -> {
+				System.out.println(n + " bottles of beer on the wall.");
+			});
+			cr.executeIfEqual(() -> {
+				System.out.println("One bottle of beer on the wall.");
+			});
+		});
+
+		System.out.println("No bottles of beer on the wall.");
+	}
+}