public static IEnumerable <IMatch> AsEnumerable(this ISearchQuery query)
{
var match = query.NextMatch();
while (match != null)
{
yield return(match);
match = query.NextMatch();
}
}
public IMatch NextMatch()
{
while (true)
{
switch (state)
{
case State.Null:
return(null);
case State.Initial:
leftMatch = leftQuery.NextMatch();
rightMatch = rightQuery.NextMatch();
if (leftMatch == null && rightMatch == null)
{
state = State.Null;
return(null);
}
else if (leftMatch != null && rightMatch != null)
{
state = State.Merge;
}
else
{
state = State.Tail;
return(leftMatch ?? rightMatch);
}
break;
case State.AdvanceLeft:
leftMatch = leftQuery.NextMatch();
if (leftMatch == null)
{
state = State.Tail;
return(rightMatch);
}
state = State.Merge;
break;
case State.AdvanceRight:
rightMatch = rightQuery.NextMatch();
if (rightMatch == null)
{
state = State.Tail;
return(leftMatch);
}
state = State.Merge;
break;
case State.Tail:
if (leftMatch == null)
{
rightMatch = rightQuery.NextMatch();
if (rightMatch == null)
{
state = State.Null;
return(null);
}
return(rightMatch);
}
if (rightMatch == null)
{
leftMatch = leftQuery.NextMatch();
if (leftMatch == null)
{
state = State.Null;
return(null);
}
return(leftMatch);
}
throw new InvalidOperationException();
case State.Merge:
if (leftMatch.Left < rightMatch.Left)
{
state = State.AdvanceLeft;
return(leftMatch);
}
else
{
state = State.AdvanceRight;
return(rightMatch);
}
default:
throw new NotSupportedException();
}
}
}