/// <summary>
/// Gets the set of terminal symbols that could follow the nonterminal symbol s
/// in the current item-set.
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public IEnumerable <ITerminalSymbol> Follows(INonterminalSymbol s)
{
var result = new HashSet <ITerminalSymbol>();
foreach (var e in items.Where(i => !i.AtEnd && i.NextSymbol == s))
{
ProductionRule rule = e.Rule;
int index;
for (index = e.DotPosition + 1; index < rule.rhs.Length; ++index)
{
foreach (var t in rule.rhs[index].First)
{
result.Add(t);
}
if (!rule.rhs[index].CanBeEmpty)
{
break;
}
}
if (index == rule.rhs.Length)
{
// This wasn't documented properly I don't think
// Also add the lookahead of the matched item if the rule can match at the end of the rule.
result.Add(e.Lookahead[0]);
}
}
return(result);
}
public ShiftReduceConflict(ProductionRule ruleToShift, ProductionRule ruleToReduce) : base("Shift-reduce conflict")
{
ShiftRule = ruleToShift;
ReduceRule = ruleToReduce;
}
public ReduceReduceConflict(ProductionRule r1, ProductionRule r2) : base("Reduce-reduce conflict")
{
Rule1 = r1;
Rule2 = r2;
}
public Item(ProductionRule rule, int dotPosition, params ITerminalSymbol[] lookahead)
{
Rule = rule;
DotPosition = dotPosition;
Lookahead = lookahead;
}