/// <summary>
/// Initializes a new instance of the <see cref="MatchKeyword"/> class.
/// </summary>
/// <param name="tokenType">The type.</param>
/// <param name="keyword">The keyword.</param>
public MatchKeyword(TokenType tokenType, string keyword)
{
tokenType.CheckNull("tokenType");
keyword.CheckNull("keyword");
keyword.Check(
s => !string.IsNullOrEmpty(s), s => new ArgumentException("The keyword cannot be an empty string."));
this.Keyword = keyword;
this.keywordCharacters = keyword.Select(c => c.ToString(CultureInfo.InvariantCulture)).ToArray();
this.TokenType = tokenType;
this.AllowAsSubString = true;
}