public void ComputeFollowSet()
{
bool FoundLambda = false;
NonTerminal lhs = Prod[0].lhs as NonTerminal;
((IList)lhs.Follow).Add(TokenLookup.TokenKind.EOI);
do
{
FollowSetChanged = false;
foreach (Production pp in Prod)
{
for (int j = 0; j < pp.rhs.Count; j++)
{
FoundLambda = ComputeFirstSetHelper(pp, j);
if (FoundLambda)
{
NonTerminal nt = pp.rhs[j] as NonTerminal;
if (nt == null)
{
continue;
}
foreach (TokenLookup.TokenKind tok in ((NonTerminal)pp.lhs).Follow)
{
if (!((IList)nt.Follow).Contains(tok))
{
((IList)nt.Follow).Add(tok);
}
}
}
}
}
} while (FollowSetChanged);
}
public bool ComputeProductionFirstSet(Production pp)
{
int k = 0;
bool Continue = false;
k = 0;
NonTerminal lhs = pp.lhs as NonTerminal;
do
{
Continue = false;
NonTerminal nt = pp.rhs[k] as NonTerminal;
if (nt != null)
{
foreach (TokenLookup.TokenKind tok in nt.First)
{
if (tok != TokenLookup.TokenKind.Lambda)
{
Production p = (Production)M[(int)lhs.Category, (int)tok];
if (p != null && p.prodno != pp.prodno)
{
MessageBox.Show("duplicate table entry productions : " + p.prodno + " and " + pp.prodno +
" category " + lhs.Category + " token " + tok);
}
else
{
M[(int)lhs.Category, (int)tok] = pp;
}
}
else
{
Continue = true;
}
}
}
else
{
Terminal t = pp.rhs[k] as Terminal;
if (t.Token != TokenLookup.TokenKind.Lambda)
{
Production p = (Production)M[(int)lhs.Category, (int)t.Token];
if (p != null && p.prodno != pp.prodno)
{
MessageBox.Show("duplicate table entry productions : " + p.prodno + " and " + pp.prodno +
" category " + lhs.Category + " token " + t.Token);
}
else
{
M[(int)lhs.Category, (int)t.Token] = pp;
}
}
else
{
Continue = true;
}
}
k = k + 1;
} while (Continue && k <= pp.rhs.Count - 1);
return(Continue);
}
public bool ComputeFirstSetHelper(Production pp, int index)
{
int k = 0;
bool Continue = false;
NonTerminal lhs = null;
if (index == pp.rhs.Count - 1)
{
return(true);
}
lhs = pp.rhs[index] as NonTerminal;
if (lhs == null)
{
return(false);
}
k = index + 1;
do
{
Continue = false;
NonTerminal nt = pp.rhs[k] as NonTerminal;
if (nt != null)
{
foreach (TokenLookup.TokenKind tok in nt.First)
{
if (tok != TokenLookup.TokenKind.Lambda && !((IList)lhs.Follow).Contains(tok))
{
((IList)lhs.Follow).Add(tok);
lhs.Follow.HasChanged = true;
}
if (tok == TokenLookup.TokenKind.Lambda)
{
Continue = true;
}
}
}
else
{
Terminal t = pp.rhs[k] as Terminal;
if (t.Token != TokenLookup.TokenKind.Lambda && !((IList)lhs.Follow).Contains(t.Token))
{
((IList)lhs.Follow).Add(t.Token);
lhs.Follow.HasChanged = true;
}
if (t.Token == TokenLookup.TokenKind.Lambda)
{
Continue = true;
}
}
k = k + 1;
} while (Continue && k <= pp.rhs.Count - 1);
return(Continue);
}
public NonTerminal FindNTermByName(string name)
{
NonTerminal nt = null;
nt = (NonTerminal)HashNTerm[name];
if (nt == null)
{
MessageBox.Show(" NonTerminal " + name + " does not exist");
return(null);
}
return(nt);
}
private Production FindLambdaProduction(NonTerminal lhs)
{
foreach (Production pp in Prod)
{
Terminal t = pp.rhs[0] as Terminal;
if (t == null)
{
continue;
}
if (pp.lhs == lhs && t.Token == TokenLookup.TokenKind.Lambda)
{
return(pp);
}
}
return(null);
}
/// <summary>
/// 预测分析表
/// </summary>
public void FillTable()
{
bool FoundLambda = false;
Production lpp = null;
M = (Production[, ]) new Production[NTerm.Count, Term.Count];
foreach (Production pp in Prod)
{
FoundLambda = ComputeProductionFirstSet(pp);
if (FoundLambda)
{
NonTerminal lhs = pp.lhs as NonTerminal;
lpp = FindLambdaProduction(lhs);
if (lpp == null)
{
continue;
}
foreach (TokenLookup.TokenKind tok in lhs.Follow)
{
if (tok == TokenLookup.TokenKind.UnKnown)
{
continue;
}
Production p = (Production)M[(int)lhs.Category, (int)tok]; // first set has precedence
if (p == null)
{
M[(int)lhs.Category, (int)tok] = lpp;
// MessageBox.Show("duplicate table entry productions : " + p.prodno + " and " + pp.prodno +
// " category " + lhs.Category + " token " + tok);
}
//else
}
}
}
}
public void ComputeFirstSet()
{
int k = 0;
bool FoundLambda = false;
bool Continue = true;
NonTerminal lhs = null;
foreach (Terminal term in Term)
{
((IList)term.First).Add(term.Token);
}
do
{
FirstSetChanged = false;
foreach (Production pp in Prod)
{
k = 0;
Continue = true;
while (Continue && k <= pp.rhs.Count - 1)
{
NonTerminal nt = pp.rhs[k] as NonTerminal;
if (nt != null)
{
FoundLambda = false;
foreach (TokenLookup.TokenKind tok in nt.First)
{
lhs = pp.lhs as NonTerminal;
if (tok != TokenLookup.TokenKind.Lambda && !((IList)lhs.First).Contains(tok))
{
((IList)lhs.First).Add(tok);
lhs.First.HasChanged = true;
}
if (tok == TokenLookup.TokenKind.Lambda)
{
FoundLambda = true;
}
}
Continue = FoundLambda;
}
else
{
FoundLambda = false;
Terminal t = pp.rhs[k] as Terminal;
lhs = pp.lhs as NonTerminal;
if (t.Token != TokenLookup.TokenKind.Lambda && !((IList)lhs.First).Contains(t.Token))
{
((IList)lhs.First).Add(t.Token);
lhs.First.HasChanged = true;
}
if (t.Token == TokenLookup.TokenKind.Lambda)
{
FoundLambda = true;
}
Continue = FoundLambda;
}
k = k + 1;
}
if (Continue && !((IList)lhs.First).Contains(TokenLookup.TokenKind.Lambda))
{
((IList)lhs.First).Add(TokenLookup.TokenKind.Lambda);
lhs.First.HasChanged = true;
}
}
} while (FirstSetChanged);
}
