public bool IsReduce(LR0State state)
{
if (state.Items.Count == 1)
{
var item = state.Items[0];
var index = item.rhs.IndexOf('.');
if (index != item.rhs.Length - 1)
{
return(false);
}
}
return(true);
}
public bool IsShift(LR0State state)
{
foreach (var item in state.Items)
{
var index = item.rhs.IndexOf('.');
if (index == item.rhs.Length - 1)
{
return(false);
}
}
return(true);
}
public bool IsAccepted(LR0State state)
{
if (state.Items.Count == 1)
{
var accItem = new LR0Item(augmentedGrammar.StartingSymbol, grammar.StartingSymbol + ".");
if (accItem.Equals(state.Items[0]))
{
return(true);
}
}
return(false);
}
public List <LR0State> CanonicalCollection()
{
var stateID = -1;
var unprocessedStats = new Stack <LR0State>();
var canonicalCollection = new List <LR0State>();
var initalElements = augmentedGrammar.Productions[augmentedGrammar.StartingSymbol];
var initalState = new LR0State(Closure(initalElements));
unprocessedStats.Push(initalState);
calculatedStates.Add(new KeyValuePair <ClosureAction, LR0State>(new ClosureAction(initalElements), initalState));
while (unprocessedStats.Count != 0)
{
var currentState = unprocessedStats.Pop();
stateID++;
currentState.StateID = stateID;
canonicalCollection.Add(currentState);
Log("State:");
Log(currentState);
augmentedGrammar.AllSymbols.ForEach(symbol =>
{
var gotoResult = Goto(currentState, symbol);
if (gotoResult.Key != null)
{
var state = gotoResult.Key;
var isNew = gotoResult.Value;
Log(symbol);
Log(state);
if (isNew == true)
{
unprocessedStats.Push(state);
}
}
});
}
return(canonicalCollection);
}
private KeyValuePair <LR0State, bool> Goto(LR0State state, string symbol)
{
LR0State resultState = null;
var isNew = true;
var inputItems = state.Items
.Where(item =>
{
var itmeSymbol = item.GetSymbolAfterDot();
if (itmeSymbol == null)
{
return(false);
}
return(itmeSymbol.Equals(symbol));
})
.ToList();
var newItems = inputItems.Select(item => item.MoveDot()).ToList();
if (newItems.Count != 0)
{
foreach (var calculatedState in calculatedStates)
{
if (calculatedState.Key.Equals(new ClosureAction(newItems)))
{
resultState = calculatedState.Value;
isNew = false;
}
}
if (resultState == null)
{
var closure = Closure(newItems);
resultState = new LR0State(closure);
calculatedStates.Add(new KeyValuePair <ClosureAction, LR0State>(new ClosureAction(newItems), resultState));
}
}
return(new KeyValuePair <LR0State, bool>(resultState, isNew));
}
public int ReduceTo(LR0State state)
{
var item = state.Items[0];
var lhsItem = item.lhs;
var rhsItem = item.rhs.Substring(0, item.rhs.Length - 1);
var newItem = new LR0Item(lhsItem, rhsItem);
var index = 0;
foreach (var originalItem in grammar.ProductionList)
{
if (originalItem.Equals(newItem))
{
return(index);
}
index++;
}
return(-1);
}