//This method is used to add elements between follow sets
public void addSet(FollowSet source, FollowSet target)
{
foreach (Symbol terminal in source.Terminals)
{
target.Terminals.Add(terminal);
}
}
// This method is used to define follow set algorithm.
public FollowSet FOLLOW(Symbol symbol)
{
FollowSet followSetBNonTerminal = new FollowSet();
foreach (Production production in this.grammar.productions)
{
foreach (Symbol nonTerminal in this.grammar.nonTerminals)
{
foreach (Tuple <Symbol, Symbol> terminals in this.grammar.getTerminalPairs())
{
string TNTRHS = this.grammar.getForm(terminals, nonTerminal, "TNT");
string TNRHS = this.grammar.getForm(terminals.Item1, nonTerminal, "TN");
if (nonTerminal.ToString().Equals(TNTRHS))
{
followSetBNonTerminal.NonTerminal = nonTerminal;
followSetBNonTerminal.Terminals = this.FIRST(terminals.Item2);
}
if (nonTerminal.ToString().Equals(TNRHS) || (nonTerminal.ToString().Equals(TNTRHS) && this.FIRST(terminals.Item2).Contains(Symbol.getEmptyWord())))
{
this.addSet(this.FOLLOW(terminals.Item2), this.FOLLOW(production.getSymbolicLHS()));
}
}
}
}
return(followSetBNonTerminal);
}
public override TokenSet Init_FollowSet(ParseNode_Root parser, TokenSet succ)
{
if (FollowSet == null)
{
followChanged = true;
FollowSet = new TokenSet(succ);
}
else if (FollowSet.Add(succ))
{
followChanged = true;
}
return(FirstSet);
}
public string ToString(ParseNode_Root parser)
{
var result = new StringBuilder(m_sNtName + " : " + rhs + " .");
if (FirstSet != null)
{
result.Append("\n lookahead " + FirstSet.ToString(parser));
}
if (FollowSet != null)
{
result.Append("\n follow " + FollowSet.ToString(parser));
}
return(result.ToString());
}
