Esempio n. 1
0
        // postfixExp to NFA
        public NFA TransiteToFNA(String postfixExp)
        {
            if (postfixExp.Length == 0)
            {
                return(new EpsilonNFA());
            }

            Stack <NFA> stack = new Stack <NFA>();

            foreach (Char token in postfixExp)
            {
                if (token == '*')
                {
                    stack.Push(Closure(stack.Pop()));
                }
                else if (token == '|')
                {
                    NFA right = stack.Pop();
                    NFA left  = stack.Pop();
                    stack.Push(Union(left, right));
                }
                else if (token == '.')
                {
                    NFA right = stack.Pop();
                    NFA left  = stack.Pop();
                    stack.Push(Concat(left, right));
                }
                else
                {
                    stack.Push(new SymbolNFA(token));
                }
            }

            return(stack.Pop());
        }
Esempio n. 2
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        // concat two NFAs
        public NFA Concat(NFA first, NFA second)
        {
            first.end.addEpsilonTransition(second.end);
            first.end.setIsEnd(false);
            NFA concated = new NFA(first.start, second.end);

            return(concated);
        }
Esempio n. 3
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        // closure nfa
        public NFA Closure(NFA nfa)
        {
            State start = new State(false);
            State end   = new State(true);

            start.addEpsilonTransition(end);
            start.addEpsilonTransition(nfa.start);

            nfa.end.addEpsilonTransition(end);
            nfa.end.addEpsilonTransition(nfa.start);
            nfa.end.setIsEnd(false);

            NFA closured = new NFA(start, end);

            return(closured);
        }
Esempio n. 4
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        // union two NFAs
        public NFA Union(NFA first, NFA second)
        {
            State start = new State(false);
            State end   = new State(true);

            start.addEpsilonTransition(first.start);
            end.addEpsilonTransition(second.start);

            first.end.addEpsilonTransition(end);
            first.end.setIsEnd(false);
            second.end.addEpsilonTransition(end);
            second.end.setIsEnd(false);

            NFA unioned = new NFA(start, end);

            return(unioned);
        }
Esempio n. 5
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        public Regex(String regularExpression)
        {
            Engine engine = new Engine();

            this.nfa = engine.TransiteToFNA(regularExpression);
        }