/// <summary>
/// Returns a <see cref="PartialNFA"/> constructed
/// by concatenating the left and right partials with a epsilon transition between
/// them
/// </summary>
/// <param name="left">Left partial NFA</param>
/// <param name="right">Right partial NFA</param>
/// <returns></returns>
public PartialNFA Concatenation(PartialNFA left, PartialNFA right)
{
return(new PartialNFA(
left.Initial,
right.Terminal,
left.Transitions
.Union(right.Transitions)
.Union(new[] { Transition(left.Terminal, Epsilon, right.Initial) })
));
}
/// <summary>
/// Returns a clone of the supplied <see cref="PartialNFA"/>
/// where each state is replaced with a new state and all transitions are mapped
/// across to use the new states
/// </summary>
/// <param name="partial"><see cref="PartialNFA"/>
/// to be cloned</param>
/// <returns></returns>
public PartialNFA Clone(
PartialNFA partial)
{
var map = Enumerable.Union(
partial.Transitions.Select(t => t.Source),
partial.Transitions.Select(t => t.Target)
).Distinct().ToDictionary(s => s, s => State());
return(new PartialNFA(
map[partial.Initial],
map[partial.Terminal],
partial.Transitions.Select(t => Transition(map[t.Source], t.Input, map[t.Target]))
));
}
/// <summary>
/// Returns a <see cref="PartialNFA"/> constructed
/// to make the inner partial optional using the Kleene star expression
/// </summary>
/// <param name="inner">Inner partial NFA to make optional</param>
/// <returns></returns>
public PartialNFA OptionalRepeating(PartialNFA inner)
{
var initial = State();
var terminal = State();
return(new PartialNFA(
initial,
terminal,
inner.Transitions
.Union(new[] {
Transition(initial, Epsilon, inner.Initial),
Transition(initial, Epsilon, terminal),
Transition(inner.Terminal, Epsilon, terminal),
Transition(inner.Terminal, Epsilon, inner.Initial),
})
));
}
/// <summary>
/// Returns a <see cref="PartialNFA"/> constructed
/// to give alternative routes between the left and right partials with epsilon
/// transitions from the new initial to the partial initials, and from the partial
/// terminals to the new terminal
/// </summary>
/// <param name="left">Left partial NFA</param>
/// <param name="right">Right partial NFA</param>s
/// <returns></returns>
public PartialNFA Alternative(PartialNFA left, PartialNFA right)
{
var initial = State();
var terminal = State();
return(new PartialNFA(
initial,
terminal,
left.Transitions
.Union(right.Transitions)
.Union(new[] {
Transition(initial, Epsilon, left.Initial),
Transition(initial, Epsilon, right.Initial),
Transition(left.Terminal, Epsilon, terminal),
Transition(right.Terminal, Epsilon, terminal),
})
));
}
/// <summary> /// Returns a <see cref="PartialNFA"/> constructed /// to optionally match the inner partial /// </summary> /// <param name="inner"></param> /// <returns></returns> public PartialNFA Optional(PartialNFA inner) => Alternative(inner, Input(Epsilon));
/// <summary> /// Returns a <see cref="PartialNFA"/> constructed /// to match one or more instances of the inner partial /// </summary> /// <param name="inner"></param> /// <returns></returns> public PartialNFA RequiredRepeating(PartialNFA inner) => Concatenation(inner, OptionalRepeating(Clone(inner)));
