org.opengis.cite.ogcapifeatures10.util.UrnValidator Maven / Gradle / Ivy

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package org.opengis.cite.ogcapifeatures10.util;

/**
 * https://github.com/BruceZu/broken_colored_glass/blob/master/project/src/main/java/URN8141.java
 *
 * @author Lyn Goltz 
 */
public class UrnValidator {

	/**
	 * 	 * DIGIT         =  0-9
	 * ALPHA         =  A-Z / a-z
	 * alphanum      =  ALPHA / DIGIT
	 * ldh           = 　alphanum / "-"
	 * NID           = (alphanum) 0*30(ldh) (alphanum)
	 * 
	 */
	private static String NID = "\\p{Alnum}[a-zA-Z0-9\\-]{0,30}\\p{Alnum}";

	/**
	 * 	 * unreserved  =  ALPHA / DIGIT / "-" / "." / "_" / "~"
	 * HEXDIG      =  DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
	 * pct-encoded =  "%" HEXDIG HEXDIG　;
	 * sub-delims  =  "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
	 * pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
	 * 
	 */
	private static String PCHAR = "[a-zA-Z0-9\\-\\._~!\\$&'\\(\\)\\*\\+,;=:@]|(%[0-9A-F]{2})";

	/**
	 * 	 * NSS = pchar * ( pchar / "/" )
	 * 
	 *
	 * @see #PCHAR
	 */
	private static String NSS = "(" + PCHAR + ")((" + PCHAR + ")|/)*";

	/**
	 * 	 * assigned-name = "urn" ":" NID ":" NSS
	 * 
	 *
	 * The leading scheme (urn:) is case-insensitive
	 *
	 * @see Wiki: Uniform
	 * Resource Name
	 */
	private static String ASSIGNED_NAME = "([uU][rR][nN]):(" + NID + "):(" + NSS + ")";

	/**
	 * 	 * fragment      =       *( pchar / "/" / "?" )
	 * 
	 */
	private static String FRAGMENT = "((" + PCHAR + ")|/|\\?)*";

	/**
	 * 	 * r-component   = pchar *( pchar / "/" / "?" )
	 * q-component   = pchar *( pchar / "/" / "?" )
	 * 
	 */
	private static String R_Q_COMPONENT = "(" + PCHAR + ")" + FRAGMENT;

	/**
	 * 	 * rq-components = [ "?+" r-component ] [ "?=" q-component ]
	 * 
	 *
	 * The order is not gurantee as the '?' can be used in fragment, and the '+' and '='
	 * can be used in pchar.
	 *
	 * @see #R_Q_COMPONENT
	 */
	private static String RQ_COMPONENTS = "((\\?\\+)(" + R_Q_COMPONENT + "))?((\\?=)(" + R_Q_COMPONENT + "))?";

	/**
	 * 	 * f-component   = fragment
	 * namestring    = assigned-name  [ rq-components ]  [ "#" f-component ]
	 * 
	 */
	private static String URN_RFC8141 = "^" + ASSIGNED_NAME + RQ_COMPONENTS + "(#" + FRAGMENT + ")?$";

	/**
	 * Checks if the passed urn is a valid urn according RFC 8141, Section 2
	 * (https://tools.ietf.org/html/rfc8141#section-2)
	 * @param urn the urn to check, null results in a invalid URN.
	 * @return true if the urn is valid according to RFC 8141, Section 2,
	 * false if the urn is null, empty or not valid.
	 */
	public boolean isValid(String urn) {
		if (urn == null)
			return false;
		return urn.matches(URN_RFC8141);
	}

}