/// <summary>
/// Accepts a conjunctive-normal-form expression backwards applier visitor.
/// </summary>
/// <param name="visitor">CNF expression visitor.</param>
public IElementCNF Accept(IElementCNFBackwardsApplierVisitor visitor)
{
ClauseCNF newExpression = new ClauseCNF();
foreach (var literal in this)
{
var resultExpression = literal.Accept(visitor);
if (resultExpression == null)
{
// any of element from the clause holds -> the whole clause holds
return(null);
}
else
{
newExpression.Add((LiteralCNF)resultExpression);
}
}
return(newExpression);
}
/// <summary>
/// Visits the expression.
/// </summary>
/// <param name="expression">Expression.</param>
public override void Visit(OrExpression expression)
{
expression.Children.ForEach(child => child.Accept(this));
ClauseCNF clause = new ClauseCNF();
for (int i = 0; i < expression.Children.Count; ++i)
{
LiteralCNF literal = Stack.Pop() as LiteralCNF;
if (literal != null)
{
clause.Add(literal);
}
else
{
Debug.Assert(false, "Source expression not in CNF!");
}
}
Stack.Push(clause);
}
