sg.atom.utils._beta.functional.FunctionalIterator.java Source code

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Here is the source code for sg.atom.utils._beta.functional.FunctionalIterator.java

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/*
 * Copyright 2011,2012 Metamarkets Group Inc.
 *
 * 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.
 */
package sg.atom.utils._beta.functional;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.Iterators;
//import com.metamx.common.guava.nary.BinaryFn;
//import com.metamx.common.guava.nary.BinaryTransformIterator;
//import com.metamx.common.guava.nary.TrinaryFn;
//import com.metamx.common.guava.nary.TrinaryTransformIterator;

import java.util.Iterator;

/**
 */
public class FunctionalIterator<T> implements Iterator<T> {

    private final Iterator<T> delegate;

    public static <T> FunctionalIterator<T> create(Iterator<T> delegate) {
        return new FunctionalIterator<T>(delegate);
    }

    public static <T> FunctionalIterator<T> fromConcatenation(Iterator<T>... toConcat) {
        return new FunctionalIterator<T>(Iterators.concat(toConcat));
    }

    public static <T> FunctionalIterator<T> fromConcatenation(Iterator<Iterator<T>> toConcat) {
        return new FunctionalIterator<T>(Iterators.concat(toConcat));
    }

    public FunctionalIterator(Iterator<T> delegate) {
        this.delegate = delegate;
    }

    public boolean hasNext() {
        return delegate.hasNext();
    }

    public T next() {
        return delegate.next();
    }

    public void remove() {
        delegate.remove();
    }

    public <RetType> FunctionalIterator<RetType> transform(Function<T, RetType> fn) {
        return new FunctionalIterator<RetType>(Iterators.transform(delegate, fn));
    }

    public <RetType> FunctionalIterator<RetType> transformCat(Function<T, Iterator<RetType>> fn) {
        return new FunctionalIterator<RetType>(Iterators.concat(Iterators.transform(delegate, fn)));
    }

    public <RetType> FunctionalIterator<RetType> keep(Function<T, RetType> fn) {
        return new FunctionalIterator<RetType>(
                Iterators.filter(Iterators.transform(delegate, fn), Predicates.notNull()));
    }

    public FunctionalIterator<T> filter(Predicate<T> pred) {
        return new FunctionalIterator<T>(Iterators.filter(delegate, pred));
    }

    public FunctionalIterator<T> drop(int numToDrop) {
        //return new FunctionalIterator<T>(new DroppingIterator<T>(delegate, numToDrop));
        return null;
    }

    public FunctionalIterator<T> limit(int limit) {
        return new FunctionalIterator<T>(Iterators.limit(delegate, limit));
    }

    public FunctionalIterator<T> concat(Iterator<T>... toConcat) {
        if (toConcat.length == 1) {
            return new FunctionalIterator<T>(Iterators.concat(delegate, toConcat[0]));
        }
        return new FunctionalIterator<T>(Iterators.concat(delegate, Iterators.concat(toConcat)));
    }

    public FunctionalIterator<T> concat(Iterator<Iterator<T>> toConcat) {
        return new FunctionalIterator<T>(Iterators.concat(delegate, Iterators.concat(toConcat)));
    }

    //    public <InType, RetType> FunctionalIterator<RetType> binaryTransform(
    //            final Iterator<InType> otherIterator, final BinaryFn<T, InType, RetType> binaryFn) {
    //        return new FunctionalIterator<RetType>(BinaryTransformIterator.create(delegate, otherIterator, binaryFn));
    //    }
    //
    //    public <InType1, InType2, RetType> FunctionalIterator<RetType> trinaryTransform(
    //            final Iterator<InType1> iterator1,
    //            final Iterator<InType2> iterator2,
    //            final TrinaryFn<T, InType1, InType2, RetType> trinaryFn) {
    //        return new FunctionalIterator<RetType>(TrinaryTransformIterator.create(delegate, iterator1, iterator2, trinaryFn));
    //    }
}