internal IEnumerable <PatternMatchProgress> MakeStep(MatchElement currentElement)
{
if (_currentPatternPart >= Pattern.PartCount)
{
yield break;
}
var isVariable = Pattern.IsVariable(_currentPatternPart);
var currentPatternPart = Pattern.GetCurrentPart(_currentPatternPart);
var isPartHardMatched = !isVariable && currentElement.Pattern.Representation.Equals(currentPatternPart);
if (isPartHardMatched)
{
//only way hard match can appear is via non-variable
yield return(NextStep());
}
if (isVariable)
{
var newVarBuffers = extendBuffers(currentElement);
//first possibility, variable ends after this word.
yield return(new PatternMatchProgress(Pattern, _currentPatternPart + 1, newVarBuffers, _varSubstitutions));
//second, variable accepts the word keep accepting other word(s)
yield return(new PatternMatchProgress(Pattern, _currentPatternPart, newVarBuffers, _varSubstitutions));
}
}
private void registerChild(MatchElement child)
{
if (child.Parent != null)
{
throw new NotSupportedException("Cannot register child with parent");
}
child.Parent = this;
}
private MatchElement[][] extendBuffers(MatchElement currentElement)
{
var extendedBuffers = new MatchElement[_varBuffers.Length][];
Array.Copy(_varBuffers, extendedBuffers, extendedBuffers.Length);
var previousBuffer = extendedBuffers[_currentPatternPart];
if (previousBuffer == null)
{
extendedBuffers[_currentPatternPart] = new[] { currentElement }
}
;
else
{
extendedBuffers[_currentPatternPart] = previousBuffer.Concat(new[] { currentElement }).ToArray();
}
return(extendedBuffers);
}
internal Match(MatchElement rootElement)
{
RootElement = rootElement;
}