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 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * http://glassfish.java.net/public/CDDL+GPL_1_1.html
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package org.glassfish.jersey.message.internal;

import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import javax.ws.rs.core.AbstractMultivaluedMap;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.RuntimeDelegate;
import javax.ws.rs.ext.RuntimeDelegate.HeaderDelegate;

import org.glassfish.jersey.internal.util.collection.ImmutableMultivaluedMap;
import org.glassfish.jersey.internal.util.collection.StringKeyIgnoreCaseMultivaluedMap;

import com.google.common.base.Function;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

/**
 * Utility class supporting the processing of message headers.
 *
 * @author Marek Potociar (marek.potociar at oracle.com)
 * @author Michal Gajdos (michal.gajdos at oracle.com)
 */
public final class HeadersFactory {

    /**
     * Create an empty inbound message headers container. Created container is mutable.
     *
     * @return a new empty mutable container for storing inbound message headers.
     */
    public static AbstractMultivaluedMap createInbound() {
        return new StringKeyIgnoreCaseMultivaluedMap();
    }

    /**
     * Get immutable empty message headers container. The factory method can be
     * used to for both message header container types  –  inbound
     * as well as outbound.
     *
     * @param  header value type. Typically {@link Object} in case of the outbound
     *     headers and {@link String} in case of the inbound headers.
     * @return an immutable empty message headers container.
     */
    public static  MultivaluedMap empty() {
        return ImmutableMultivaluedMap.empty();
    }

    /**
     * Create an empty outbound message headers container. Created container is mutable.
     *
     * @return a new empty mutable container for storing outbound message headers.
     */
    public static AbstractMultivaluedMap createOutbound() {
        return new StringKeyIgnoreCaseMultivaluedMap();
    }

    /**
     * Convert a message header value, represented as a general object, to it's
     * string representation.
     * 

     * This method defers to {@link RuntimeDelegate#createHeaderDelegate} to
     * obtain a {@link HeaderDelegate} to convert the value to a {@code String}.
     * If a {@link HeaderDelegate} is not found then the {@code toString()}
     * method on the header object is utilized.
     *
     * @param headerValue the header value represented as an object.
     * @param rd runtime delegate instance to be used for header delegate
     *     retrieval. If {@code null}, a default {@code RuntimeDelegate}
     *     instance will be {@link RuntimeDelegate#getInstance() obtained} and
     *     used.
     * @return the string representation of the supplied header value.
     */
    @SuppressWarnings("unchecked")
    public static String asString(final Object headerValue, RuntimeDelegate rd) {
        if (headerValue instanceof String) {
            return (String) headerValue;
        }
        if (rd == null) {
            rd = RuntimeDelegate.getInstance();
        }

        final HeaderDelegate hp = rd.createHeaderDelegate(headerValue.getClass());
        return (hp != null) ? hp.toString(headerValue) : headerValue.toString();
    }

    /**
     * Returns string view of list of header values. Any modifications to the underlying list are visible to the view,
     * the view also supports removal of elements. Does not support other modifications.
     *
     * @param headerValues header values.
     * @param rd RuntimeDelegate instance (can be passed in as a perf. optimization) or {@code null} (in that case
     *           {@link RuntimeDelegate#getInstance()} will be called for each element conversion.
     * @return String view of header values.
     */
    public static List asStringList(final List headerValues, final RuntimeDelegate rd) {
        if (headerValues == null || headerValues.isEmpty()) {
            return Collections.emptyList();
        }
        return Lists.transform(headerValues, new Function() {
            @Override
            public String apply(Object input) {
                return (input == null) ? "[null]" : HeadersFactory.asString(input, rd);
            }

        });
    }

    /**
     * Returns string view of passed headers. Any modifications to the headers are visible to the view, the view also
     * supports removal of elements. Does not support other modifications.
     *
     * @param headers headers.
     * @return String view of headers.
     */
    public static MultivaluedMap asStringHeaders(final MultivaluedMap headers) {
        final RuntimeDelegate rd = RuntimeDelegate.getInstance();
        return new AbstractMultivaluedMap(
                Maps.transformValues(headers, new Function, List>() {
                    @Override
                    public List apply(List input) {
                        return HeadersFactory.asStringList(input, rd);
                    }
                })
        ) {};
    }

    /**
     * Converts a list of message header values to a single string value (with individual values separated by
     * {@code ','}).
     *
     * Each single header value is converted to String using a
     * {@link javax.ws.rs.ext.RuntimeDelegate.HeaderDelegate} if one is available
     * via {@link javax.ws.rs.ext.RuntimeDelegate#createHeaderDelegate(java.lang.Class)}
     * for the header value class or using its {@code toString()} method if a header
     * delegate is not available.
     *
     * @param values list of individual header values
     * @param rd RuntimeDelegate instance (can be passed in as a perf. optimization) or {@code null} (in that case
     *           {@link RuntimeDelegate#getInstance()} will be called for each element conversion.
     * @return single string consisting of all the values passed in as a parameter. If values parameter is {@code null},
     *         {@code null} is returned. If the list of values is empty, an empty string is returned.
     */
    public static String asHeaderString(List values, RuntimeDelegate rd) {
        if (values == null) {
            return null;
        }
        final Iterator stringValues = asStringList(values, rd).iterator();
        if (!stringValues.hasNext()) {
            return "";
        }

        StringBuilder buffer = new StringBuilder(stringValues.next());
        while (stringValues.hasNext()) {
            buffer.append(',').append(stringValues.next());
        }

        return buffer.toString();
    }

    /**
     * Preventing instantiation
     */
    private HeadersFactory() {
    }
}
    

    

    

            

    

            



    
    






    
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