lojix/logic/src/main/com/thesett/aima/logic/fol/isoprologparser/PrologParser.java
public Directive peekAndConsumeDirective() throws SourceCodeException
    {
        if (peekAndConsumeTrace())
        {
            return Directive.Trace;
        }

        if (peekAndConsumeInfo())
        {
            return Directive.Info;
        }

        if (peekAndConsumeUser())
        {
            return Directive.User;
        }

        return null;
    }
public Directive peekAndConsumeDirective() throws SourceCodeException
    {
        if (peekAndConsumeTrace())
        {
            return Directive.Trace;
        }

        if (peekAndConsumeInfo())
        {
            return Directive.Info;
        }

        if (peekAndConsumeUser())
        {
            return Directive.User;
        }

        return null;
    }
Peeks and consumes the next interactive system directive.

@return The directive, or <tt>null</tt> if none is found.

@throws SourceCodeException If the source being parsed does not match the grammar.