/// <summary>
/// Creates a new FA that matches the specified FA expression or empty
/// </summary>
/// <param name="expr">The expression to make optional</param>
/// <param name="accept">The symbol to accept</param>
/// <returns>A new FA that will match the specified expression or empty</returns>
public static CharFA <TAccept> Optional(CharFA <TAccept> expr, TAccept accept = default(TAccept))
{
var result = expr.Clone();
var f = result.FirstAcceptingState;
f.AcceptSymbol = accept;
result.EpsilonTransitions.Add(f);
return(result);
}
/// <summary>
/// Creates a new FA that will match a repetition of one or more of the specified FA expression
/// </summary>
/// <param name="expr">The expression to repeat</param>
/// <param name="accept">The symbol to accept</param>
/// <returns>A new FA that matches the specified FA one or more times</returns>
public static CharFA <TAccept> Repeat(CharFA <TAccept> expr, TAccept accept = default(TAccept))
{
var result = new CharFA <TAccept>();
var final = new CharFA <TAccept>(true, accept);
var e = expr.Clone();
var afa = e.FirstAcceptingState;
afa.IsAccepting = false;
afa.EpsilonTransitions.Add(final);
afa.EpsilonTransitions.Add(result);
result.EpsilonTransitions.Add(e);
return(result);
}