protected override void Extract()
{
StringBuilder stringBuilder = new StringBuilder();
while (CurrentChar.IsLetter() || isWordChar(CurrentChar))
{
stringBuilder.Append(CurrentChar);
NextChar();
}
text = stringBuilder.ToString();
type = TokenType.RESERVED_WORDS.ContainsKey(text.ToLower())
? TokenType.RESERVED_WORDS[text.ToLower()]
: KeywordToken.StringLiteral;
}