public static ParseState Closure(this IEnumerable <Item> items, Grammar grammar)
{
HashSet <Item> closure = new HashSet <Item>(items);
HashSet <Item> toAdd = new HashSet <Item>();
do
{
toAdd.Clear();
foreach (var item in closure)
{
if (item.Position == item.Production.Body.Length)
{
continue;
}
BnfTerm term = item.Production.Body[item.Position];
if (term is NonTerminal)
{
NonTerminal nonTerm = term as NonTerminal;
foreach (var production in grammar.Productions.Where(a => a.Head.Equals(nonTerm)))
{
toAdd.Add(new Item(production, 0));
}
}
}
}while (closure.UnionWithAddedCount(toAdd) > 0);
return(new ParseState(closure, IsAcceptingState(closure, grammar)));
}
public static ParseState Closure(this IEnumerable<Item> items, Grammar grammar)
{
HashSet<Item> closure = new HashSet<Item>(items);
HashSet<Item> toAdd = new HashSet<Item>();
do
{
toAdd.Clear();
foreach (var item in closure)
{
if (item.Position == item.Production.Body.Length)
continue;
BnfTerm term = item.Production.Body[item.Position];
if (term is NonTerminal)
{
NonTerminal nonTerm = term as NonTerminal;
foreach (var production in grammar.Productions.Where(a => a.Head.Equals(nonTerm)))
toAdd.Add(new Item(production, 0));
}
}
}
while (closure.UnionWithAddedCount(toAdd) > 0);
return new ParseState(closure, IsAcceptingState(closure, grammar));
}
public static Automaton CreateAutomaton(Grammar g)
{
//initialise to closure of start item
HashSet<ParseState> states = new HashSet<ParseState>();
states.Add(g.Productions.Where(a => a.Head.Equals(g.Root)).Select(a => new Item(a, 0)).Closure(g));
HashSet<ParseStateTransition> transitions = new HashSet<ParseStateTransition>();
HashSet<ParseState> sToAdd = new HashSet<ParseState>();
HashSet<ParseStateTransition> tToAdd = new HashSet<ParseStateTransition>();
do
{
sToAdd.Clear();
tToAdd.Clear();
foreach (var state in states)
{
foreach (var item in state)
{
if (item.Production.Body.Length == item.Position)
continue;
BnfTerm term = item.Production.Body[item.Position];
ParseState j = state.Goto(term, g);
sToAdd.Add(j);
tToAdd.Add(new ParseStateTransition(state, term, j));
}
}
}
while (states.UnionWithAddedCount(sToAdd) != 0 | transitions.UnionWithAddedCount(tToAdd) != 0);
return new Automaton(transitions, g);
}
public static Automaton CreateAutomaton(Grammar g)
{
//initialise to closure of start item
HashSet <ParseState> states = new HashSet <ParseState>();
states.Add(g.Productions.Where(a => a.Head.Equals(g.Root)).Select(a => new Item(a, 0)).Closure(g));
HashSet <ParseStateTransition> transitions = new HashSet <ParseStateTransition>();
HashSet <ParseState> sToAdd = new HashSet <ParseState>();
HashSet <ParseStateTransition> tToAdd = new HashSet <ParseStateTransition>();
do
{
sToAdd.Clear();
tToAdd.Clear();
foreach (var state in states)
{
foreach (var item in state)
{
if (item.Production.Body.Length == item.Position)
{
continue;
}
BnfTerm term = item.Production.Body[item.Position];
ParseState j = state.Goto(term, g);
sToAdd.Add(j);
tToAdd.Add(new ParseStateTransition(state, term, j));
}
}
}while (states.UnionWithAddedCount(sToAdd) != 0 | transitions.UnionWithAddedCount(tToAdd) != 0);
return(new Automaton(transitions, g));
}
