/**
 * Copyright 2008 - 2015 The Loon Game Engine Authors
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 * 
 * @project loon
 * @author cping
 * @email：javachenpeng@yahoo.com
 * @version 0.5
 */
package loon.utils.reply;

import loon.utils.reply.ActView.ActViewListener;
import loon.utils.reply.VarView.VarViewListener;

public abstract class Port<T> implements VarViewListener<T>, ActViewListener<T> {

	public <P> Port<P> compose(final Function<P, T> fn) {
		final Port<T> outer = this;
		return new Port<P>() {
			@Override
			public void onEmit(P value) {
				outer.onEmit(fn.apply(value));
			}
		};
	}

	public <P extends T> Port<P> filtered(final Function<? super P, Boolean> pred) {
		final Port<T> outer = this;
		return new Port<P>() {
			@Override
			public void onEmit(P value) {
				if (pred.apply(value)) {
					outer.onEmit(value);
				}
			}
		};
	}

	public <P extends T> Port<P> andThen(final Port<? super P> after) {
		final Port<T> before = this;
		return new Port<P>() {
			@Override
			public void onEmit(P e) {
				before.onEmit(e);
				after.onEmit(e);
			}
		};
	}

	@Override
	public final void onChange(T value, T oldValue) {
		onEmit(value);
	}
}
