public void NonTerminal_Predicate_And()
{
// predicates should not adjust the
// iterator once the expression is evaluated.
AExpression Digit = new CharacterClass {ClassExpression = "[0-9]"};
// regex expression: \d+
var input = Encoding.UTF8.GetBytes("01234567890123456789");
var iterator = new ByteInputIterator(input);
AExpression andPredicate = new OneOrMore(Digit).And();
var visitor = new NpegParserVisitor(iterator);
andPredicate.Accept(visitor);
Assert.IsTrue(visitor.IsMatch);
Assert.IsTrue(iterator.Index == 0);
}
public void NonTerminal_Predicate_Or()
{
// predicates should not adjust the
// iterator once the expression is evaluated.
AExpression Digit = new CharacterClass {ClassExpression = "[0-9]"};
// equivalent to: regex '^' '$'
// regex expression: ^\d+$
var bytes = Encoding.UTF8.GetBytes("0123456abcdefg");
var iterator = new ByteInputIterator(bytes);
AExpression notPredicate = new OneOrMore(Digit).And().Sequence(new NotPredicate(new AnyCharacter()));
var visitor = new NpegParserVisitor(iterator);
notPredicate.Accept(visitor);
Assert.IsFalse(visitor.IsMatch); // should fail
Assert.IsTrue(iterator.Index == 0);
}
public override void VisitLeave(OneOrMore expression)
{
IsMatchPredicate local = _matchStack.Pop();
_matchStack.Push(
delegate(IInputIterator iterator)
{
Int32 cnt = 0;
Int32 savePosition = iterator.Index;
while (local(iterator))
{
cnt++;
if (savePosition == iterator.Index)
{
//InfiniteLoopDetectedException
break;
}
savePosition = iterator.Index;
}
iterator.Index = savePosition;
return (cnt > 0);
}
);
}
public override void VisitExecute(OneOrMore expression)
{
}
public override void VisitEnter(OneOrMore expression)
{
}
public override void VisitLeave(OneOrMore expression)
{
terminal.Peek().Append(")+");
}
public override void VisitEnter(OneOrMore expression)
{
terminal.Peek().Append("(");
}
public abstract void VisitEnter(OneOrMore expression);
public abstract void VisitLeave(OneOrMore expression);
public abstract void VisitExecute(OneOrMore expression);
