public ProductionItem(
MarkedProduction markedProduction,
IReadOnlySet <Terminal <TTokenKind> > lookaheads)
{
MarkedProduction = markedProduction;
Lookaheads = lookaheads ?? Set <Terminal <TTokenKind> > .Empty;
}
public override int GetHashCode()
{
unchecked
{
var hashCode = MarkedProduction.GetHashCode();
hashCode = (hashCode * 397) ^ Lookaheads.GetHashCode();
return(hashCode);
}
}
public bool Equals(ProductionItem <TTokenKind> other, ProductionItemComparison comparison)
{
switch (comparison)
{
case ProductionItemComparison.MarkedProductionOnly:
return(MarkedProduction.Equals(other.MarkedProduction)); // CORE is the same
case ProductionItemComparison.LookaheadsOnly:
return(Lookaheads.SetEquals(other.Lookaheads));
case ProductionItemComparison.MarkedProductionAndLookaheads:
default:
return(MarkedProduction.Equals(other.MarkedProduction) && Lookaheads.SetEquals(other.Lookaheads));
}
}
/// <summary> /// Get the remaining symbols after the dot symbol in normal order. /// </summary> public IEnumerable <Symbol> GetRemainingSymbolsAfterDotSymbol() => MarkedProduction.GetRemainingSymbolsAfterDotSymbol();
/// <summary> /// Get the symbol after the dot. /// </summary> public TSymbol TryGetDotSymbol <TSymbol>() where TSymbol : Symbol => MarkedProduction.TryGetDotSymbol <TSymbol>();
/// <summary> /// Get the successor item of a shift/goto action created by 'shifting the dot'. /// </summary> public ProductionItem <TTokenKind> WithShiftedDot() // NOTE: we only make a shallow copy of the read-only lookaheads set => new ProductionItem <TTokenKind>(MarkedProduction.WithShiftedDot(), Lookaheads);
/// <summary>
/// Does this LR(k) item set contain a kernel item with a given CORE (dotted production).
/// </summary>
public bool CoreOfKernelContains(MarkedProduction dottedProduction)
{
return(_anyLookaheads
? KernelItems.Select(item => item.MarkedProduction).Contains(dottedProduction)
: _kernelItems.Contains(dottedProduction.AsLr0Item <TTokenKind>()));
}