/// <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)
{
NfaState head = nfa.NewState();
NfaState tail = nfa.NewState();
NfaState lastHead = head;
// 如果没有上限，则需要特殊处理。
int times = maxTimes == int.MaxValue ? minTimes : maxTimes;
if (times == 0)
{
// 至少要构造一次。
times = 1;
}
for (int i = 0; i < times; i++)
{
innerExp.BuildNfa(nfa);
lastHead.Add(nfa.HeadState);
if (i >= minTimes)
{
// 添加到最终的尾状态的转移。
lastHead.Add(tail);
}
lastHead = nfa.TailState;
}
// 为最后一个节点添加转移。
lastHead.Add(tail);
// 无上限的情况。
if (maxTimes == int.MaxValue)
{
// 在尾部添加一个无限循环。
nfa.TailState.Add(nfa.HeadState);
}
nfa.HeadState = head;
nfa.TailState = tail;
}
/// <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)
{
NfaState head = nfa.NewState();
NfaState tail = nfa.NewState();
left.BuildNfa(nfa);
head.Add(nfa.HeadState);
nfa.TailState.Add(tail);
right.BuildNfa(nfa);
head.Add(nfa.HeadState);
nfa.TailState.Add(tail);
nfa.HeadState = head;
nfa.TailState = tail;
}
private static DfaMatcher MakeMatcher()
{
// a?[ab]
var first = new NfaState();
var last = new NfaState();
var end = new NfaState();
var a1 = Atom.From('a');
var a2 = Atom.From('a', 'b');
first.Add(a1, last);
first.Add(last);
last.Add(a2, end);
var nfa = new Nfa(first, end);
return(new DfaMatcher(nfa.ToDfa().Minimize()));
}
public static Nfa Single(Atom terminal)
{
var start = new NfaState();
var end = new NfaState();
start.Add(terminal, end);
return(new Nfa(start, end));
}
/// <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)
{
left.BuildNfa(nfa);
NfaState head = nfa.HeadState;
NfaState tail = nfa.TailState;
right.BuildNfa(nfa);
tail.Add(nfa.HeadState);
nfa.HeadState = head;
}
private static DfaMatcher MakeMatcher()
{
// [ab]?[abc][ab]?
var first = new NfaState();
var center = new NfaState();
var last = new NfaState();
var end = new NfaState();
var ab = Atom.From('a', 'b');
var ac = Atom.From('a', 'c');
first.Add(ab, center);
first.Add(center);
center.Add(ac, last);
last.Add(ab, end);
last.Add(end);
var nfa = new Nfa(first, end);
return(new DfaMatcher(nfa.ToDfa().Minimize()));
}
/// <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;
}
}
public void TransformShouldCreateDfa()
{
var state1 = new NfaState();
var state2 = new NfaState();
var state3 = new NfaState();
state1.Add(Atom.From('1'), state2);
state2.Add(Atom.From('2'), state3);
state3.Add(Atom.From('3'), state1);
var nfa = new Nfa(state1, state3);
var dfa = nfa.ToDfa().Minimize();
Assert.IsNotNull(dfa);
Assert.AreEqual(3, new DfaPlumber(dfa).StateCount);
}