public LookAheadSet CreateFilter(LookAheadSet set)
{
LookAheadSet result = new LookAheadSet(_maxLength);
// Handle special cases
if (this.Size() <= 0 || set.Size() <= 0)
{
return(this);
}
// Create combinations
for (int i = 0; i < _elements.Count; i++)
{
var first = (Sequence)_elements[i];
for (int j = 0; j < set._elements.Count; j++)
{
var second = (Sequence)set._elements[j];
if (first.StartsWith(second))
{
result.Add(first.Subsequence(second.Length()));
}
}
}
return(result);
}
private LookAheadSet FindLookAhead(ProductionPatternElement elem,
int length,
int dummy,
CallStack stack,
LookAheadSet filter)
{
LookAheadSet result;
if (elem.IsToken())
{
result = new LookAheadSet(length);
result.Add(elem.Id);
}
else
{
var pattern = GetPattern(elem.Id);
result = FindLookAhead(pattern, length, stack, filter);
if (stack.Contains(pattern.Name))
{
result = result.CreateRepetitive();
}
}
return(result);
}
public LookAheadSet CreateRepetitive()
{
LookAheadSet result = new LookAheadSet(_maxLength);
for (int i = 0; i < _elements.Count; i++)
{
var seq = (Sequence)_elements[i];
if (seq.IsRepetitive())
{
result.Add(seq);
}
else
{
result.Add(new Sequence(true, seq));
}
}
return(result);
}
public LookAheadSet CreateIntersection(LookAheadSet set)
{
LookAheadSet result = new LookAheadSet(_maxLength);
for (int i = 0; i < _elements.Count; i++)
{
var seq1 = (Sequence)_elements[i];
var seq2 = set.FindSequence(seq1);
if (seq2 != null && seq1.IsRepetitive())
{
result.Add(seq2);
}
else if (seq2 != null)
{
result.Add(seq1);
}
}
return(result);
}
public LookAheadSet CreateOverlaps(LookAheadSet set)
{
LookAheadSet result = new LookAheadSet(_maxLength);
for (int i = 0; i < _elements.Count; i++)
{
var seq = (Sequence)_elements[i];
if (set.IsOverlap(seq))
{
result.Add(seq);
}
}
return(result);
}
public LookAheadSet CreateCombination(LookAheadSet set)
{
LookAheadSet result = new LookAheadSet(_maxLength);
// Handle special cases
if (this.Size() <= 0)
{
return(set);
}
else if (set.Size() <= 0)
{
return(this);
}
// Create combinations
for (int i = 0; i < _elements.Count; i++)
{
var first = (Sequence)_elements[i];
if (first.Length() >= _maxLength)
{
result.Add(first);
}
else if (first.Length() <= 0)
{
result.AddAll(set);
}
else
{
for (int j = 0; j < set._elements.Count; j++)
{
var second = (Sequence)set._elements[j];
result.Add(first.Concat(_maxLength, second));
}
}
}
return(result);
}
public LookAheadSet CreateNextSet(int token)
{
LookAheadSet result = new LookAheadSet(_maxLength - 1);
for (int i = 0; i < _elements.Count; i++)
{
var seq = (Sequence)_elements[i];
var value = seq.GetToken(0);
if (value != null && token == (int)value)
{
result.Add(seq.Subsequence(1));
}
}
return(result);
}
