/// <summary>
/// Remove a state from the list
/// </summary>
/// <typeparam name="Q"></typeparam>
/// <param name="states"></param>
/// <param name="key"></param>
public static void RemoveTranistionFunction <Q, S>(this List <TransitionFunction <NfaState <Q>, S, NfaState <Q> > > tf,
NfaState <Q> state, S symbol)
{
tf.Remove(
tf.Find(
t =>
t.From.Id.Equals(state.Id) &&
((symbol == null && t.TransitionSymbols == null) || t.TransitionSymbols.Equals(symbol))));
}
/// <summary>
/// Override the GetNextStates methdo in the base
/// class to add the lambda feature
/// It gets all the next states of the specified state
/// and that's reachable through the symbol <see cref="S"/>
/// or the lambda, lambda is represented as null.
/// </summary>
/// <param name="state">The state for which to get the next states</param>
/// <param name="symbol">The connector symbol</param>
/// <returns>List of all next states if any, empty list otherwise</returns>
public override List <NfaState <Q> > GetNextStates(NfaState <Q> state, S symbol)
{
var list = new List <NfaState <Q> >();
if (state != null && IsExists(state.Id))
{
IEnumerable <TransitionFunction <NfaState <Q>, S, NfaState <Q> > > transitions = (from t in TransitionTable
where
t.From.Id.Equals(state.Id) &&
t.TransitionSymbols != null &&
t.TransitionSymbols.Contains(
symbol)
select t).Union(
from t in TransitionTable.OfType <PredicateTransitionFunction <NfaState <Q>, S, NfaState <Q> > >()
where t.From.Id.Equals(state.Id) && t.PredicateLambda != null && t.PredicateLambda(symbol)
select(TransitionFunction <NfaState <Q>, S, NfaState <Q> >) t
).Distinct();
foreach (var tf in transitions)
{
list.Add(tf.To);
// For each one check to see of there are some states
// reachable via lambda
List <NfaState <Q> > nextLambdaStates = GetNextLambdaStates(tf.To);
// add the states reachable via lambda
if (nextLambdaStates != null)
{
list.AddRange(nextLambdaStates);
}
}
// Search for lambda transtion from the state and other states
List <NfaState <Q> > nextStateLambdaStates = GetNextLambdaStates(state);
if (nextStateLambdaStates != null)
{
// if found, iterate over them and check if
// they have a transition with the same symbol
foreach (var st in nextStateLambdaStates)
{
list.AddRange(from t in TransitionTable
where t.From.Id.Equals(st.Id) &&
t.TransitionSymbols != null &&
t.TransitionSymbols.Contains(symbol)
select t.To);
}
}
}
else
{
return(null);
}
return(list);
}
/// <summary>
/// Add new state, this method check if the
/// state <see cref="T"/> exists, if not
/// add the state.
/// </summary>
/// <param name="state"></param>
public void AddState(NfaState <Q> state)
{
if (!IsExists(state.Id))
{
if (state.StateType == StateType.StartState)
{
CurrentStates.Add(state);
}
States.Add(state);
}
}
/// <summary>
/// Get all the next states of the specified state
/// </summary>
/// <param name="state">The state for which to get the next states</param>
/// <returns>List of all next states if any, empty list otherwise</returns>
public List <NfaState <Q> > GetNextStates(NfaState <Q> state)
{
var list = new List <NfaState <Q> >();
if (state != null && IsExists(state.Id))
{
list.AddRange(from s in
TransitionTable.FindAll(tf => tf.From.Id.Equals(state.Id))
select s.To);
}
else
{
return(null);
}
return(list);
}
/// <summary>
/// Set state type
/// </summary>
/// <param name="key">The state key</param>
/// <param name="type">The type to be set</param>
public void SetStateType(Q key, StateType type)
{
NfaState <Q> state = null;
if ((state = GetState(key)) != null)
{
state.StateType = type;
if (state.StateType == StateType.StartState)
{
CurrentStates.Add(state);
}
else
{
CurrentStates.RemoveState(key);
}
}
else
{
throw new Exception("State doesn't exists");
}
}
/// <summary>
/// Get all the next states of the specified state
/// and that's reachable through the symbol <see cref="S"/>
/// </summary>
/// <param name="state">The state for which to get the next states</param>
/// <param name="symbol">The connector symbol</param>
/// <returns>List of all next states if any, empty list otherwise</returns>
public virtual List <NfaState <Q> > GetNextStates(NfaState <Q> state, S symbol)
{
var list = new List <NfaState <Q> >();
if (state != null && IsExists(state.Id))
{
list.AddRange((from s in
TransitionTable.FindAll(tf => tf.From.Id.Equals(state.Id) &&
tf.TransitionSymbols.Contains(symbol))
select s.To).Union(
from t in TransitionTable.OfType <PredicateTransitionFunction <NfaState <Q>, S, NfaState <Q> > >()
where
t.From.Id.Equals(state.Id) && t.PredicateLambda != null &&
t.PredicateLambda(symbol)
select t.To
).Distinct());
}
else
{
return(null);
}
return(list);
}
