/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

package org.apache.jena.util.iterator;

import java.util.Iterator;
import java.util.function.Predicate;

/**
 * boolean functions wrapped to be used in filtering iterators.
 * 
 * Deprecated in favor of {@link Predicate}.
 */
@Deprecated
public abstract class Filter<T> implements Predicate<T> 
{
    @Override
    public boolean test(T o) {
		return accept(o);
	}

	@Deprecated
	public abstract boolean accept(T o);

	@Deprecated
	public ExtendedIterator<T> filterKeep(Iterator<T> it) {
		return new FilterIterator<>(this, it);
	}

	/**
	 * Use {@link #and(Predicate)} instead.
	 */
	@Deprecated
	public Filter<T> and(final Filter<T> other) {
		return other.isAny() ? this : new Filter<T>() {
			@Override
			public boolean accept(T x) {
				return Filter.this.accept(x) && other.accept(x);
			}
		};
	}

	/**
	 * Answer true iff this filter will deliver true for any argument. Should
	 * never be overridden except by classes generated by any() below.
	 * 
	 * No longer needed after Java 8: optimizations of this kind are now a compiler/JVM concern.
	 */
	@Deprecated
	public boolean isAny() {
		return false;
	}

	/**
	 * A Filter that accepts everything it's offered.
	 * 
	 * @deprecated use Filter.any()
	 */
	@SuppressWarnings({ "unchecked", "rawtypes" })
	// Knowingly suppressed - maximum backward compatibility.
	@Deprecated
	public static final Filter any = new Filter() {
		@Override
		public final boolean isAny() {
			return true;
		}

		@Override
		public final boolean accept(Object o) {
			return true;
		}

		@Override
		public Filter and(Filter other) {
			return other;
		}

		@Override
		public ExtendedIterator filterKeep(Iterator it) {
			return WrappedIterator.create(it);
		}
	};

	/**
	 * Use Java 8's lambda syntax, e.g. x -> true.
	 */
	@Deprecated
	public static <T> Filter<T> any() {
		return new Filter<T>() {
			@Override
			public final boolean isAny() {
				return true;
			}

			@Override
			public final boolean accept(T o) {
				return true;
			}

			@Override
			public Filter<T> and(Filter<T> other) {
				return other;
			}

			@Override
			public ExtendedIterator<T> filterKeep(Iterator<T> it) {
				return WrappedIterator.create(it);
			}
		};
	}
}