本文整理汇总了C++中Grammar::GetStartSymbol方法的典型用法代码示例。如果您正苦于以下问题：C++ Grammar::GetStartSymbol方法的具体用法？C++ Grammar::GetStartSymbol怎么用？C++ Grammar::GetStartSymbol使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类Grammar的用法示例。
在下文中一共展示了Grammar::GetStartSymbol方法的2个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: MakeLLTables
MMap MakeLLTables(Grammar& g)
{
const GrammarSymbol* pMain = g.FindSymbol(L"Main");
if (pMain == nullptr)
{
throw std::exception("Main syntax must be defined!");
}
if (g.GetStartSymbol() == nullptr)
{
throw std::exception("Main syntax must be defined! (start)");
}
const FirstSets first = BuildFirstSets3(g);
const FollowSets follow = BuildFolowSets3(g, first);
PrintFirst(std::wcout, first);
std::wcout << std::endl;
PrintFollow(std::wcout, follow);
MMap M = BuildMTable(first, follow, g);
std::wcout << L"M table" << std::endl;
Print(std::wcout, M, g);
return M;
}示例2: BuildFolowSets3
//controi todos os follow(A) da gramatica g
FollowSets BuildFolowSets3(Grammar& g, const FirstSets& first)
{
FollowSets follow;
//Follow(start-symbol):= {$};
follow.AddToSet(g.GetStartSymbol(), g.endmarker());
//for all nonterminals A != start-symbol do Follow(A):={};
for (int i = 0 ; i < g.GetNumOfGrammarSymbols(); i++)
{
const GrammarSymbol* pgs = g.GetSymbol(i);
if (!pgs->IsTerminal() && pgs != g.GetStartSymbol())
{
follow.CreateGet(pgs);
}
}
bool changed = true;
while (changed)
{
changed = false;
// Para cada producao A -> X1...Xn
for (int k = 0 ; k < g.GetNumOfProductions(); k++)
{
const Production& A = g.GetProduction(k);
Print(std::wcout, A);
std::wcout << std::endl;
for (int i = 0 ; i < A.GetNumOfRightSymbols(); i++)
{
//If there is a production A -> alfa B beta , then everything in FIRST(beta) except epsilon
//is in FOLLOW(B).
const GrammarSymbol* Xi = A.GetRightSymbol(i);
//Para cada nao terminal Xi da producao
if (!Xi->IsTerminal())
{
//add First(Xi+1..Xn) - {epsilon} to Follow(Xi)
std::set<const GrammarSymbol*> firstXi1_Xn;
bool epsilon_is_in_firstXi1_Xn = false;
//se Xi não é o ultimo
if (i < (A.GetNumOfRightSymbols() - 1))
{
firstXi1_Xn = GetFirstSet(first, g, A, i + 1);
for (auto it = firstXi1_Xn.begin(); it != firstXi1_Xn.end(); ++it)
{
if (*it != g.epsilon())
{
if (follow.AddToSet(Xi, *it))
{
changed = true;
}
}
else
{
epsilon_is_in_firstXi1_Xn = true;
}
}
}
// If there is a production A -> alfaB, or a production A -> alfa B beta , where
// FIRST(beta) contains epsilon, then everything in FOLLOW (A) is in FOLLOW (B) .
if (i == (A.GetNumOfRightSymbols() - 1) ||
epsilon_is_in_firstXi1_Xn)
{
//add Follow(A) to Follow(Xi)
auto FollowA = follow.Get(A.GetLeftSymbol());
for (auto it = FollowA.begin(); it != FollowA.end(); ++it)
{
if (follow.AddToSet(Xi, *it))
{
changed = true;
}
}
}
}//para este Xi
} //para cada Xi
} //para cada producao
} //enquando mudar...
return follow;
}