private Production CreateProduction(NonTerminal lvalue, BnfTermList operands)
{
Production prod = new Production(lvalue);
//create RValues list skipping Empty terminal and collecting grammar hints
foreach (BnfTerm operand in operands)
{
if (operand == Grammar.Empty)
{
continue;
}
//Collect hints as we go - they will be added to the next non-hint element
GrammarHint hint = operand as GrammarHint;
if (hint != null)
{
hint.Position = prod.RValues.Count;
prod.Hints.Add(hint);
continue;
}
//Check if it is a Terminal or Error element
Terminal t = operand as Terminal;
if (t != null)
{
prod.Flags |= ProductionFlags.HasTerminals;
if (t.Category == TokenCategory.Error)
{
prod.Flags |= ProductionFlags.IsError;
}
}
//Add the operand info and LR0 Item
_itemID++;
LR0Item item = new LR0Item(prod, prod.RValues.Count, _itemID);
prod.LR0Items.Add(item);
prod.RValues.Add(operand);
}//foreach operand
//set the flags
if (lvalue == Data.AugmentedRoot)
{
prod.Flags |= ProductionFlags.IsInitial;
}
if (prod.RValues.Count == 0)
{
prod.Flags |= ProductionFlags.IsEmpty;
}
//Add final LRItem
_itemID++;
prod.LR0Items.Add(new LR0Item(prod, prod.RValues.Count, _itemID));
return(prod);
}
} //method
//Checks Reduce productions of an action for a ReduceThis hint. If found, the production is moved to the beginning of the list.
private bool CheckReduceHint(ActionRecord action)
{
foreach (Production prod in action.ReduceProductions)
{
GrammarHint reduceHint = GetHint(prod, prod.RValues.Count, HintType.ReduceThis);
if (reduceHint != null)
{
action.ReduceProductions.Remove(prod);
action.ReduceProductions.Insert(0, prod);
action.ActionType = ParserActionType.Reduce;
action.ConflictResolved = true;
return(true);
} //if
} //foreach prod
return(false);
} //method
//Checks shift items for PreferShift grammar hint. Hints are associated with a particular position
// inside production, which is in fact an LR0 item. The LR0 item is available thru shiftItem.Core property.
// If PreferShift hint found, moves the hint-owning shiftItem to the beginning of the list and returns true.
private bool CheckShiftHint(ActionRecord action)
{
foreach (LRItem shiftItem in action.ShiftItems)
{
GrammarHint shiftHint = GetHint(shiftItem.Core.Production, shiftItem.Core.Position, HintType.PreferShift);
if (shiftHint != null)
{
action.ActionType = ParserActionType.Shift;
action.ShiftItems.Remove(shiftItem);
action.ShiftItems.Insert(0, shiftItem);
action.ConflictResolved = true;
return(true);
} //if
} //foreach shiftItem
return(false);
} //method
private Production CreateProduction(NonTerminal lvalue, BnfTermList operands)
{
Production prod = new Production(lvalue);
GrammarHintList hints = null;
//create RValues list skipping Empty terminal and collecting grammar hints
foreach (BnfTerm operand in operands)
{
if (operand == _grammar.Empty)
{
continue;
}
//Collect hints as we go - they will be added to the next non-hint element
GrammarHint hint = operand as GrammarHint;
if (hint != null)
{
if (hints == null)
{
hints = new GrammarHintList();
}
hints.Add(hint);
continue;
}
//Add the operand and create LR0 Item
prod.RValues.Add(operand);
prod.LR0Items.Add(new LR0Item(_lastItemId++, prod, prod.RValues.Count - 1, hints));
hints = null;
}//foreach operand
//set the flags
if (prod.RValues.Count == 0)
{
prod.Flags |= ProductionFlags.IsEmpty;
}
//Add final LRItem
ComputeProductionFlags(prod);
prod.LR0Items.Add(new LR0Item(_lastItemId++, prod, prod.RValues.Count, hints));
return(prod);
}
protected GrammarHint ImplyPrecedenceHere(int precedence, Associativity associativity) {
var hint = new GrammarHint(HintType.Precedence, null);
hint.Precedence = precedence;
hint.Associativity = associativity;
return hint;
}
