/// <summary>
/// Adds, removes, or sets an attribute. If <paramref name="value"/> is not null, the
/// attribute's value will be <paramref name="value"/> after conversion to string. If the
/// value is null and the attribute exists, it is removed. If the value is not null and the
/// attribute does not exist, it is added.
/// </summary>
/// <param name="element"></param>
/// <param name="name"></param>
/// <param name="value"></param>
/// <exception cref="NotSupportedException">The given navigable does not support editing.</exception>
public static void SetAttributeValue(this IXPathNavigable element, XName name, object value)
{
Checker.NotNull(element, "element");
Checker.NotNull(name, "name");
element.GetSelfOrNewElementNavigator().RawSetAttribute(name, (value == null) ? null : value.ToString());
}
/// <summary>
/// Retrieves the value of the attribute having the given name, or an empty result if there is no such attribute.
/// </summary>
/// <param name="element"></param>
/// <param name="name"></param>
/// <returns></returns>
public static Opt <string> AttributeValueOpt(this IXPathNavigable element, XName name)
{
Checker.NotNull(element, "element");
Checker.NotNull(name, "name");
var nav = element.GetSelfOrNewElementNavigator();
var hasValue = true;
var value = nav.RawGetAttribute(name);
if (value.Equals(string.Empty))
{
// Since an empty string is returned for a missing attribute, we must check whether
// the value is absent or simply blank.
hasValue = nav.RawHasAttribute(name);
}
return(Opt.Create(hasValue, value));
}
/// <summary>
/// Determines whether this element contains an attribute matching the given XName.
/// </summary>
/// <param name="element"></param>
/// <param name="name"></param>
/// <returns></returns>
public static bool HasAttribute(this IXPathNavigable element, XName name)
{
Checker.NotNull(element, "element");
Checker.NotNull(name, "name");
return(element.GetSelfOrNewElementNavigator().RawHasAttribute(name));
}
