internal static IEnumerable <FeatureCover> GetFeatureCovers(ParsedUtterance expression, ComposedGraph graph)
{
var features = createFeatures(expression, graph);
var index = new FeatureIndex(features);
return(generateCovers(index, 0, expression));
}
private static IEnumerable <FeatureCover> generateCovers(FeatureIndex index, int currentPosition, ParsedUtterance expression)
{
if (index.Length == 0)
{
//there are no possible covers
return(new FeatureCover[0]);
}
if (index.Length - 1 == currentPosition)
{
//we are at bottom of recursion
//we will initiate covers that will be extended later through the recursion
var newCovers = new List <FeatureCover>();
foreach (var feature in index.GetFeatures(currentPosition))
{
var cover = new FeatureCover(feature, expression);
newCovers.Add(cover);
}
return(newCovers);
}
//extend covers that we got from deeper recursion
var previousCovers = generateCovers(index, currentPosition + 1, expression);
var extendedCovers = new List <FeatureCover>();
foreach (var cover in previousCovers)
{
foreach (var feature in index.GetFeatures(currentPosition))
{
extendedCovers.AddRange(cover.Extend(feature));
}
}
return(extendedCovers);
}