/// <summary>
/// Splits the given partition with this group
/// </summary>
/// <param name="current">The current partition</param>
/// <returns>The resulting partition</returns>
public DFAPartition Split(DFAPartition current)
{
DFAPartition partition = new DFAPartition();
foreach (DFAState state in states)
{
partition.AddState(state, current);
}
return(partition);
}
/// <summary>
/// Refines this partition into another one
/// </summary>
/// <returns>The refined partition</returns>
public DFAPartition Refine()
{
DFAPartition newPartition = new DFAPartition();
// For each group in the current partition
// Split the group and add the resulting groups to the new partition
foreach (DFAStateGroup group in groups)
{
newPartition.groups.AddRange(group.Split(this).groups);
}
return(newPartition);
}
/// <summary>
/// Gets the minimal automaton equivalent to this ine
/// </summary>
/// <returns>The minimal DFA</returns>
public DFA Minimize()
{
DFAPartition current = new DFAPartition(this);
DFAPartition newPartition = current.Refine();
while (newPartition.GroupCount != current.GroupCount)
{
current = newPartition;
newPartition = current.Refine();
}
return(new DFA(newPartition.GetDFAStates()));
}
/// <summary>
/// Adds a state to this partition, coming from the given old partition
/// </summary>
/// <param name="state">The state to add</param>
/// <param name="old">The old partition</param>
public void AddState(DFAState state, DFAPartition old)
{
bool added = false;
// For each group in the resulting groups set
foreach (DFAStateGroup group in groups)
{
// If the current state can be in this resulting group according to the old partition :
if (AddState_SameGroup(group.Representative, state, old))
{
// Add the state to the group
group.AddState(state);
added = true;
}
}
// The state cannot be in any groups : create a new group
if (!added)
{
groups.Add(new DFAStateGroup(state));
}
}
/// <summary>
/// Determines whether two states should be in the same group
/// </summary>
/// <param name="s1">A state</param>
/// <param name="s2">Another state</param>
/// <param name="old">The old partition</param>
/// <returns></returns>
private static bool AddState_SameGroup(DFAState s1, DFAState s2, DFAPartition old)
{
if (s1.Transitions.Count != s2.Transitions.Count)
{
return(false);
}
// For each transition from state 1
foreach (CharSpan key in s1.Transitions)
{
// If state 2 does not have a transition with the same value : not same group
if (!s2.HasTransition(key))
{
return(false);
}
// Here State1 and State2 have both a transition of the same value
// If the target of these transitions are in the same group in the old partition : same transition
if (old.AddState_GetGroupOf(s1.GetChildBy(key)) != old.AddState_GetGroupOf(s2.GetChildBy(key)))
{
return(false);
}
}
return(true);
}
