public override Expression ToRegExp(Entity entity)
{
if (entity == null)
{
throw new ArgumentNullException(nameof(entity));
}
int number = Number;
Sign sign = Sign;
if (number > 0 && sign == Sign.MoreThanOrEqual)
{
number--;
sign = Sign.MoreThan;
}
if (sign == Sign.MoreThanOrEqual)
{
return(new RegExpIteration(entity.ToRegExp(), false));
}
if (number < 1)
{
return(new RegExpIteration(entity.ToRegExp(), true));
}
Expression expression = entity.ToRegExp();
Expression left = new RegExpConstIteration(expression, number);
Expression right = new RegExpIteration(expression, true);
return(new RegExpConcat(left, right));
}
public override Expression Optimize()
{
bool somethingChanged;
Expression previous;
IList <Expression> oldList = ConcatHelper.Iterate(Expressions.Select(e => e.Optimize())).ToList();
IList <Expression> newList;
do
{
somethingChanged = false;
newList = new List <Expression>();
previous = null;
foreach (Expression expression in oldList)
{
if (expression == Empty.Instance)
{
somethingChanged = true;
continue;
}
if (previous == null)
{
previous = expression;
continue;
}
Iteration iteration1 = previous.As <Iteration>();
Iteration iteration2 = expression.As <Iteration>();
if (iteration1 != null || iteration2 != null)
{
if (iteration1 != null && iteration2 != null && iteration1.Expression == iteration2.Expression)
{
if (iteration1.IsPositive && iteration2.IsPositive)
{
newList.Add(iteration1.Expression);
}
previous = new Iteration(iteration1.Expression, iteration1.IsPositive || iteration2.IsPositive);
somethingChanged = true;
continue;
}
Iteration iteration;
Expression newExpression;
if (iteration1 != null)
{
iteration = iteration1;
newExpression = expression;
}
else
{
iteration = iteration2;
newExpression = previous;
}
if (iteration.Expression == newExpression && !iteration.IsPositive)
{
previous = new Iteration(newExpression, true);
somethingChanged = true;
continue;
}
}
ConstIteration constIteration1 = previous.As <ConstIteration>();
ConstIteration constIteration2 = expression.As <ConstIteration>();
if (constIteration1 != null || constIteration2 != null)
{
if (constIteration1 != null && constIteration2 != null && constIteration1.Expression == constIteration2.Expression)
{
previous = new ConstIteration(constIteration1.Expression, constIteration1.IterationCount + constIteration2.IterationCount);
somethingChanged = true;
continue;
}
ConstIteration constIteration;
Expression newExpression;
if (constIteration1 != null)
{
constIteration = constIteration1;
newExpression = expression;
}
else
{
constIteration = constIteration2;
newExpression = previous;
}
if (constIteration.Expression == newExpression)
{
previous = new ConstIteration(newExpression, constIteration.IterationCount + 1);
somethingChanged = true;
continue;
}
}
if (constIteration1 != null && iteration2 != null && constIteration1.Expression == iteration2.Expression)
{
if (constIteration1.IterationCount > 2)
{
newList.Add(new ConstIteration(constIteration1.Expression, constIteration1.IterationCount - 1));
}
else
{
newList.Add(constIteration1.Expression);
}
previous = new Iteration(iteration2.Expression, true);
somethingChanged = true;
continue;
}
if (iteration1 != null && constIteration2 != null && iteration1.Expression == constIteration2.Expression)
{
newList.Add(new Iteration(iteration1.Expression, true));
if (constIteration2.IterationCount > 2)
{
previous = new ConstIteration(constIteration2.Expression, constIteration2.IterationCount - 1);
}
else
{
previous = constIteration2.Expression;
}
somethingChanged = true;
continue;
}
newList.Add(previous);
previous = expression;
}
if (previous != null)
{
newList.Add(previous);
}
oldList = newList;
somethingChanged |= TryToCompress(oldList);
} while (somethingChanged);
return(ConcatHelper.MakeExpression(newList));
}