protected override List <ProductionInLR0> closure(List <ProductionInLR0> productions)
{
List <ProductionInLR0> generatedList = new List <ProductionInLR0>();
generatedList.AddRange(productions);
for (int i = 0; i < generatedList.Count; i++)
{
ProductionInLR1 oldProduction = generatedList[i] as ProductionInLR1;
string token = generatedList[i].NextTokenOfPoint;
if (token != null && inputGrammer.nonTerminalTokens.Contains(token))
{
foreach (Production production in inputGrammer[token])
{
ProductionInLR1 newProduction = new ProductionInLR1(production, generatedFirst.getFirstFromPart(oldProduction.Values, oldProduction.PointPos + 1, oldProduction.searchTokens));
// 检查项集内是否有同心项（或者完全相同），有则不添加
bool noNeedToAdd = false;
foreach (ProductionInLR1 production1 in generatedList)
{
if (production1.hasSameCoreWith(newProduction))
{
noNeedToAdd = true;
production1.searchTokens = production1.searchTokens.Union(newProduction.searchTokens).ToList();
}
}
if (!noNeedToAdd)
{
generatedList.Add(newProduction);
}
}
}
}
return(generatedList);
}
public LL1Table(InputGrammer inputGrammer) : base(inputGrammer)
{
generatedFirst = new GenerateFirst(inputGrammer);
GenerateFollow generatedFollow = new GenerateFollow(inputGrammer, generatedFirst);
if (!checkLeft())
{
throw new FailToGenerateLL1Exception("含有左递归或左公因子");
}
foreach (Production production in inputGrammer.userProductions)
{
List <string> firstSetOfRightPart = generatedFirst.getFirstFromPart(production.Values);
foreach (string token in firstSetOfRightPart.Where(i => (!inputGrammer.nonTerminalTokens.Contains(i) && i != PublicFunc.EPSILON)))
{
Item item = new Item(production.Key, token, production.ToString());
checkConflict(item);
table.Add(item);
}
if (firstSetOfRightPart.Contains(PublicFunc.EPSILON))
{
foreach (string token in generatedFollow[production.Key].Where(i => !inputGrammer.nonTerminalTokens.Contains(i)))
{
Item item = new Item(production.Key, token, production.ToString());
checkConflict(item);
table.Add(item);
}
}
}
}
public GenerateFollow(InputGrammer inputGrammer, GenerateFirst generatedFirst)
{
foreach (string token in inputGrammer.nonTerminalTokens)
{
followSet.Add(new Production(token, new List <string>()));
}
// 加入$符号
GetValuesByKey(inputGrammer.nonTerminalTokens[0], followSet).Add(ENDSYMBOL);
int changeTotal;
do
{
changeTotal = 0;
foreach (Production production in inputGrammer.userProductions)
{
List <string> valuesInFollow = GetValuesByKey(production.Key, followSet);
for (int i = 0; i < production.Values.Count; i++)
{
string token = production.Values[i];
if (inputGrammer.nonTerminalTokens.Contains(token))
{
List <string> valuesOfTokenInFollow = GetValuesByKey(token, followSet);
if (i != production.Values.Count - 1)
{
bool hasEpsilon = false;
if (ExtendElementWithoutEpsilon(generatedFirst.getFirstFromPart(production.Values, i + 1), valuesOfTokenInFollow, ref hasEpsilon))
{
changeTotal++;
}
if (hasEpsilon && ExtendElement(valuesInFollow, valuesOfTokenInFollow))
{
changeTotal++;
}
}
else if (ExtendElement(valuesInFollow, valuesOfTokenInFollow))
{
changeTotal++;
}
}
}
}
} while (changeTotal != 0);
}
// 检查左递归或左公因子
public bool checkLeft()
{
foreach (string token in inputGrammer.nonTerminalTokens)
{
// S->A | B 求First(A)与First(B)的交集是否存在
List <Production> productions = inputGrammer[token];
for (int i = 0; i < productions.Count; i++)
{
for (int j = i + 1; j < productions.Count; j++)
{
if (generatedFirst.getFirstFromPart(productions[i].Values).Intersect(generatedFirst.getFirstFromPart(productions[j].Values)).Count() > 0)
{
return(false);
}
}
}
}
return(true);
}
