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RFC 3986 compliant URI implementation.
There is a newer version: 0.8.1
/*
 * Copyright 2017 dmfs GmbH
 *
 * 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 org.dmfs.rfc3986.params;

import org.dmfs.iterators.AbstractConvertedIterator;
import org.dmfs.iterators.AbstractFilteredIterator;
import org.dmfs.iterators.ConvertedIterator;
import org.dmfs.iterators.FilteredIterator;
import org.dmfs.rfc3986.UriEncoded;

import java.util.Iterator;


/**
 * The value of a parameter that be present once or not at all.
 *
 * @author Marten Gajda
 */
public final class OptionalParameter implements Optional
{
    private final ParamType mParamType;
    private final Iterable mDelegate;


    public OptionalParameter(ParamType paramType, final Iterable> delegate)
    {
        mParamType = paramType;
        mDelegate = new Iterable()
        {
            @Override
            public Iterator iterator()
            {
                return new ConvertedIterator<>(
                        new FilteredIterator<>(
                                delegate.iterator(),
                                new AbstractFilteredIterator.IteratorFilter>()
                                {
                                    @Override
                                    public boolean iterate(Pair element)
                                    {
                                        return element.key().normalized().equals(mParamType.name());
                                    }
                                }),
                        new AbstractConvertedIterator.Converter>()
                        {
                            @Override
                            public V convert(Pair element)
                            {
                                return mParamType.decodedValue(element.value());
                            }
                        });
            }
        };
    }


    @Override
    public boolean isPresent()
    {
        return mDelegate.iterator().hasNext();
    }


    @Override
    public V value(V defaultValue)
    {
        Iterator iterator = mDelegate.iterator();
        return iterator.hasNext() ? iterator.next() : defaultValue;
    }
}