/**
* Constructor with an extension name.
*
* @param name The extension name.
* @throws IllegalArgumentException The given name is not a valid token.
*/
public WebSocketExtension(String name) {
// Check the validity of the name.
if (Token.isValid(name) == false) {
// The name is not a valid token.
throw new IllegalArgumentException("'name' is not a valid token.");
}
mName = name;
mParameters = new LinkedHashMap<String, String>();
}
/**
* Set a value to the specified parameter.
*
* @param key The name of the parameter.
* @param value The value of the parameter. If not {@code null}, it must be a valid token. Note
* that <a href="http://tools.ietf.org/html/rfc6455" >RFC 6455</a> says "<i>When using the
* quoted-string syntax variant, the value after quoted-string unescaping MUST conform to the
* 'token' ABNF.</i>"
* @return {@code this} object.
* @throws IllegalArgumentException
* <ul>
* <li>The key is not a valid token.
* <li>The value is not {@code null} and it is not a valid token.
* </ul>
*/
public WebSocketExtension setParameter(String key, String value) {
// Check the validity of the key.
if (Token.isValid(key) == false) {
// The key is not a valid token.
throw new IllegalArgumentException("'key' is not a valid token.");
}
// If the value is not null.
if (value != null) {
// Check the validity of the value.
if (Token.isValid(value) == false) {
// The value is not a valid token.
throw new IllegalArgumentException("'value' is not a valid token.");
}
}
mParameters.put(key, value);
return this;
}
/**
* Parse a string as a {@link WebSocketExtesion}. The input string should comply with the format
* described in <a href= "https://tools.ietf.org/html/rfc6455#section-9.1">9.1. Negotiating
* Extensions</a> in <a href="https://tools.ietf.org/html/rfc6455" >RFC 6455</a>.
*
* @param string A string that represents a WebSocket extension.
* @return A new {@link WebSocketExtension} instance that represents the given string. If the
* input string does not comply with RFC 6455, {@code null} is returned.
*/
public static WebSocketExtension parse(String string) {
if (string == null) {
return null;
}
// Split the string by semi-colons.
String[] elements = string.trim().split("\\s*;\\s*");
if (elements.length == 0) {
// Even an extension name is not included.
return null;
}
// The first element is the extension name.
String name = elements[0];
if (Token.isValid(name) == false) {
// The extension name is not a valid token.
return null;
}
// The first element is the extension name.
WebSocketExtension extension = new WebSocketExtension(name);
// For each "{key}[={value}]".
for (int i = 1; i < elements.length; ++i) {
// Split by '=' to get the key and the value.
String[] pair = elements[i].split("\\s*=\\s*", 2);
// If {key} is not contained.
if (pair.length == 0 || pair[0].length() == 0) {
// Ignore.
continue;
}
// The name of the parameter.
String key = pair[0];
if (Token.isValid(key) == false) {
// The parameter name is not a valid token.
// Ignore this parameter.
continue;
}
// The value of the parameter.
String value = extractValue(pair);
if (value != null) {
if (Token.isValid(value) == false) {
// The parameter value is not a valid token.
// Ignore this parameter.
continue;
}
}
// Add the pair of the key and the value.
extension.setParameter(key, value);
}
return extension;
}