public static NfaFragment ZeroOrOne(NfaFragment fragment)
{
NfaFragment result = new NfaFragment();
result.Start = new NfaState(NfaStateKind.Split);
result.Outs.Add(result.Start.Out);
result.Start.Out.Add(fragment.Start);
result.Outs.AddRange(fragment.Outs);
return(result);
}
public static NfaFragment Or(IEnumerable <NfaFragment> children)
{
var result = new NfaFragment();
result.Start = new NfaState(NfaStateKind.Split);
var output = new List <List <NfaState> >();
foreach (var fragment in children)
{
result.Start.Out.Add(fragment.Start);
result.Outs.Add(fragment.Start.Out);
}
return(result);
}
public static NfaFragment ZeroOrMore(NfaFragment inner)
{
var s = new NfaState(NfaStateKind.Split);
s.Out.Add(inner.Start);
foreach (var danglingInnerOut in inner.Outs)
{
danglingInnerOut.Add(s);
}
var result = new NfaFragment();
result.Start = s;
result.Outs.Add(s.Out);
return(result);
}
public static NfaFragment Cat(IEnumerable <NfaFragment> children)
{
var result = new NfaFragment();
NfaFragment lastFragment = null;
if (children.Count() == 0)
{
result.Start = new NfaState(NfaStateKind.Split);
result.Outs.Add(result.Start.Out);
}
else
{
foreach (var fragment in children)
{
if (lastFragment == null)
{
result.Start = fragment.Start;
}
else
{
foreach (var dangling in lastFragment.Outs)
{
dangling.Add(fragment.Start);
}
}
lastFragment = fragment;
}
if (lastFragment == null)
{
result.Outs = new List <List <NfaState> >();
}
else
{
result.Outs = new List <List <NfaState> >(lastFragment.Outs);
}
}
return(result);
}
