private SppfNode ConstructInternalSppf(IEnumerable <Item> successes, Sentence s)
{
// var root = new SymbolNode(Grammar.Start, 0, s.Count);
var root = new SppfWord(Grammar.Start, 0, s.Count);
var processed = new HashSet <Item>();
var nodes = new Dictionary <SppfNode, SppfNode>();
nodes[root] = root;
foreach (var success in successes)
{
BuildTree(nodes, processed, root, success);
}
return(root);
}
private void ProcessQ(int i)
{
if (i < _a.Count)
{
// create an SPPF node v labelled(a_i, i, i + 1)
var v2 = new SppfWord(_a[i], i, i + 1);
// while Q ̸= ∅ {
while (!_Q.IsEmpty)
{
// remove an element, Λ = (B ::= α · a_i β, h, w) say, from Q
var Λ = _Q.TakeOne();
if (Λ.DecoratedProduction.NextWord != _a[i])
{
throw new Exception();
// continue;
}
var h = Λ.StartPosition;
var w = Λ.SppfNode;
var β0 = Λ.DecoratedProduction.TailFirst;
// let y = MAKE NODE(B ::= α a_i · β, h, i + 1, w, v, V)
var productionAdvanced = Λ.DecoratedProduction.Increment();
var y = MakeNode(productionAdvanced, h, i + 1, w, v2);
var newItem = new EarleyItem(productionAdvanced, h, y);
// if β ∈ Σ_N { add (B ::= α a_i · β, h, y) to E_i+1 }
if (PrefixInSigma(β0))
{
_E[i + 1].Add(newItem);
}
// if β = a_i+1 β′ { add (B ::= α a_i · β, h, y) to Q′ }
else
{
if (i + 1 < _a.Count)
{
var aNext = _a[i + 1];
if (β0 == aNext)
{
_QPrime.Add(newItem);
}
}
}
}
}
}
internal SppfWord GetOrSet(Word item, int j, int i)
{
SppfWord y;
var dict = _wordDicts[j];
if (!dict.TryGetValue(item, out y))
{
var newY = new SppfWord(item, j, i);
dict[item] = newY;
y = newY;
}
if (i != y.EndPosition)
{
throw new Exception(string.Format("Invalid assumption; need to include {0} in hash", nameof(i)));
}
return(y);
}
