public void Push(AstNode node, ParserState state)
{
_data.Add(new ParserStackElement(node, state));
}
private bool AddClosureItems(ParserState state)
{
bool result = false;
for (int i = 0; i < state.Items.Count; i++)
{
LRItem item = state.Items[i];
NonTerminal nextNT = item.Core.NextElement as NonTerminal;
if (nextNT == null) continue;
foreach (Production prod in nextNT.Productions)
{
LR0Item core = prod.LR0Items[0];
LRItem newItem = TryFindItem(state, core);
if (newItem == null)
{
newItem = new LRItem(state, core);
state.Items.Add(newItem);
result = true;
}
newItem.NewLookaheads.AddRange(item.Core.TailFirsts);
if (item.Core.TailIsNullable && !item.PropagateTargets.Contains(newItem))
item.PropagateTargets.Add(newItem);
}
}
return result;
}
public ParserStackElement(AstNode node, ParserState state)
{
Node = node;
State = state;
}
private Dictionary<string, LR0ItemList> GetStateShifts(ParserState state)
{
Dictionary<string, LR0ItemList> shifts = new Dictionary<string, LR0ItemList>();
LR0ItemList list;
foreach (LRItem item in state.Items)
{
GrammarTerm term = item.Core.NextElement;
if (term == null) continue;
LR0Item shiftedItem = item.Core.Production.LR0Items[item.Core.Position + 1];
if (!shifts.TryGetValue(term.Key, out list))
shifts[term.Key] = list = new LR0ItemList();
list.Add(shiftedItem);
}
return shifts;
}
private ParserState FindOrCreateState(LR0ItemList lr0Items)
{
string key = CalcItemListKey(lr0Items);
ParserState result;
if (_stateHash.TryGetValue(key, out result))
return result;
result = new ParserState("S" + _data.States.Count, lr0Items);
_data.States.Add(result);
_stateHash[key] = result;
return result;
}
private LRItem FindItem(ParserState state, Production production, int position)
{
foreach (LRItem item in state.Items)
if (item.Core.Production == production && item.Core.Position == position)
return item;
string msg = string.Format("Failed to find an LRItem in state {0} by production [{1}] and position {2}. ",
state, production.ToString(), position.ToString());
throw new CompilerException(msg);
}
private LRItem TryFindItem(ParserState state, LR0Item core)
{
foreach (LRItem item in state.Items)
if (item.Core == core)
return item;
return null;
}
public SyntaxError(SourceLocation location, string message, ParserState state)
{
Location = location;
Message = message;
State = state;
}
public void AddError(SourceLocation location, string message, ParserState state)
{
Errors.Add(new SyntaxError(location, message, state));
}
private void ExecuteShiftAction(ActionRecord action)
{
_stack.Push(_currentToken, _currentState);
_currentState = action.NewState;
NextToken();
}