/// <summary>
/// 根据当前的正则表达式构造 NFA。
/// </summary>
/// <param name="nfa">要构造的 NFA。</param>
internal override void BuildNfa(Nfa nfa)
{
innerExp.BuildNfa(nfa);
if (TrailingExpression != null)
{
NfaState head = nfa.HeadState;
TrailingHeadState = nfa.TailState;
TrailingExpression.BuildNfa(nfa);
TrailingHeadState.Add(nfa.HeadState);
nfa.HeadState = head;
TrailingHeadState.StateType = NfaStateType.TrailingHead;
nfa.TailState.StateType = NfaStateType.Trailing;
}
}
/// <summary>
/// 返回当前对象的字符串表示形式。
/// </summary>
/// <returns>当前对象的字符串表示形式。</returns>
public override string ToString()
{
StringBuilder builder = new StringBuilder();
if (BeginningOfLine)
{
builder.Append('^');
}
builder.Append(innerExp.ToString());
if (TrailingExpression != null)
{
if (TrailingExpression == EndOfLine)
{
builder.Append('$');
}
else
{
builder.Append('/');
builder.Append(TrailingExpression.ToString());
}
}
return(builder.ToString());
}