juneau-core/juneau-marshall/src/main/java/org/apache/juneau/http/header/Allow.java

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package org.apache.juneau.http.header;

import java.util.*;
import java.util.function.*;

import org.apache.juneau.http.annotation.*;

/**
 * Represents a parsed <l>Allow</l> HTTP response header.
 *
 * <p>
 * Valid methods for a specified resource. To be used for a 405 Method not allowed.
 *
 * <h5 class='figure'>Example</h5>
 * <p class='bcode w800'>
 * 	Allow: GET, HEAD
 * </p>
 *
 * <h5 class='topic'>RFC2616 Specification</h5>
 *
 * The Allow entity-header field lists the set of methods supported by the resource identified by the Request-URI.
 * The purpose of this field is strictly to inform the recipient of valid methods associated with the resource.
 * An Allow header field MUST be present in a 405 (Method Not Allowed) response.
 *
 * <p class='bcode w800'>
 * 	Allow   = "Allow" ":" #Method
 * </p>
 *
 * <p>
 * Example of use:
 * <p class='bcode w800'>
 * 	Allow: GET, HEAD, PUT
 * </p>
 *
 * <p>
 * This field cannot prevent a client from trying other methods.
 * However, the indications given by the Allow header field value SHOULD be followed.
 *
 * <p>
 * The actual set of allowed methods is defined by the origin server at the time of each request.
 *
 * <p>
 * The Allow header field MAY be provided with a PUT request to recommend the methods to be supported by the new or
 * modified resource.
 *
 * <p>
 * The server is not required to support these methods and SHOULD include an Allow header in the response giving the
 * actual supported methods.
 *
 * <p>
 * A proxy MUST NOT modify the Allow header field even if it does not understand all the methods specified, since the
 * user agent might
 * have other means of communicating with the origin server.
 *
 * <ul class='seealso'>
 * 	<li class='extlink'>{@doc ExtRFC2616}
 * </ul>
 */
@Header("Allow")
public class Allow extends BasicCsvArrayHeader {

	private static final long serialVersionUID = 1L;
	private static final String NAME = "Allow";

	/**
	 * Convenience creator.
	 *
	 * @param value
	 * 	The header value.
	 * 	<br>Can be <jk>null</jk>.
	 * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
	 */
	public static Allow of(String value) {
		if (value == null)
			return null;
		return new Allow(value);
	}

	/**
	 * Convenience creator.
	 *
	 * @param value
	 * 	The header value.
	 * 	<br>Can be <jk>null</jk>.
	 * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
	 */
	public static Allow of(List<String> value) {
		if (value == null)
			return null;
		return new Allow(value);
	}

	/**
	 * Convenience creator with delayed value.
	 *
	 * <p>
	 * Header value is re-evaluated on each call to {@link #getValue()}.
	 *
	 * @param value
	 * 	The supplier of the header value.
	 * 	<br>Can be <jk>null</jk>.
	 * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
	 */
	public static Allow of(Supplier<List<String>> value) {
		if (value == null)
			return null;
		return new Allow(value);
	}

	/**
	 * Constructor.
	 *
	 * @param value
	 * 	The header value.
	 * 	<br>Can be <jk>null</jk>.
	 */
	public Allow(String value) {
		super(NAME, value);
	}

	/**
	 * Constructor.
	 *
	 * @param value
	 * 	The header value.
	 * 	<br>Can be <jk>null</jk>.
	 */
	public Allow(List<String> value) {
		super(NAME, value);
	}

	/**
	 * Constructor with delayed value.
	 *
	 * <p>
	 * Header value is re-evaluated on each call to {@link #getValue()}.
	 *
	 * @param value
	 * 	The supplier of the header value.
	 * 	<br>Can be <jk>null</jk>.
	 */
	public Allow(Supplier<List<String>> value) {
		super(NAME, value);
	}
}