private void LeoMemoization(EarleyItem earleyItem, int setNumber)
{
if (!Sets[setNumber].IsItemLeoEligible(earleyItem))
{
return;
}
Symbol penult = earleyItem.GetItemPenult();
LeoItem predecessorLeoItem = FindLeoItemPredecessor(earleyItem);
if (predecessorLeoItem != null)
{
Sets[predecessorLeoItem.GetOrignPosition()]
.AddLeoItem(new LeoItem(
predecessorLeoItem.GetDottedRule(),
predecessorLeoItem.GetOrignPosition(),
penult
));
}
else
{
Sets[earleyItem.GetOrignPosition()]
.AddLeoItem(new LeoItem(
new DottedRule(earleyItem.GetRule(), earleyItem.GetRulePosition() + 1),
earleyItem.GetOrignPosition(),
penult
));
}
}
private bool LeoReducer(EarleyItem completed, int setNumber)
{
int position = completed.GetOrignPosition();
Symbol lhs = completed.GetRule().GetLeftHandSideOfRule();
EarleySet set = Sets[position];
LeoItem transitiveItem = set.FindLeoItemBySymbol(lhs);
if (transitiveItem == null)
{
return(false);
}
EarleyItem newEarleyItem = new EarleyItem(
setNumber,
transitiveItem.GetDottedRule(),
transitiveItem.GetOrignPosition()
);
EarleyItem current = Sets[transitiveItem.GetOrignPosition()].GetEarleyItemList()
.Find(el => el.GetDottedRule().Equals(transitiveItem.GetDottedRule()) && el.GetOrignPosition() == transitiveItem.GetOrignPosition());
if (current.GetCurrentPrevSymbolList() != null && current.GetCurrentPrevSymbolList().Count > 0)
{
newEarleyItem.AddPredecessorLink(current, position);
}
newEarleyItem.AddReducerLink(completed, position);
AddToSet(
newEarleyItem,
setNumber,
"LeoReducer"
);
return(true);
}