private Node BuildTree(EarleyRule rule, int stateIdx)
{
if (rule == null)
{
throw new SyntaxException($"Attempt to complete an empty rule in #{stateIdx} state");
}
var node = new Node {
Symbol = rule.Name
};
int matchedIdx = rule.Dot - 1;
while (matchedIdx >= 0)
{
var matchedTerm = rule[matchedIdx] as NonTerminal;
if (matchedTerm != null)
{
int idx = matchedIdx;
var derivatives = _chart[stateIdx]
.FinalRules(matchedTerm)
.Where(r => _chart[r.Start].Contains(rule.WithDot(idx)));
var rules = derivatives as IList <EarleyRule> ?? derivatives.ToList();
var child = BuildTree(rules.First(), stateIdx);
node.Add(child);
foreach (var deriv in rules.Skip(1))
{
child.Next = BuildTree(deriv, stateIdx);
child = child.Next;
}
stateIdx = rules[0].Start;
}
else
{
node.Add(new Node {
Symbol = rule[matchedIdx]
});
stateIdx--;
}
matchedIdx--;
}
return(node);
}
private Node BuildTree(EarleyRule rule, int stateIdx)
{
if (rule == null)
throw new SyntaxException($"Attempt to complete an empty rule in #{stateIdx} state");
var node = new Node { Symbol = rule.Name };
int matchedIdx = rule.Dot - 1;
while (matchedIdx >= 0)
{
var matchedTerm = rule[matchedIdx] as NonTerminal;
if (matchedTerm != null)
{
int idx = matchedIdx;
var derivatives = _chart[stateIdx]
.FinalRules(matchedTerm)
.Where(r => _chart[r.Start].Contains(rule.WithDot(idx)));
var rules = derivatives as IList<EarleyRule> ?? derivatives.ToList();
var child = BuildTree(rules.First(), stateIdx);
node.Add(child);
foreach (var deriv in rules.Skip(1))
{
child.Next = BuildTree(deriv, stateIdx);
child = child.Next;
}
stateIdx = rules[0].Start;
}
else
{
node.Add(new Node { Symbol = rule[matchedIdx] });
stateIdx--;
}
matchedIdx--;
}
return node;
}
