Use java to convert regular expressions to NFA

Use java to convert regular expressions to NFA
I used java to implement a conversion program from a regular expression to NFA. below is my code

package com.siwanghu.regextoNFA;public class Node {    private int id;    private static int ID=0;         public Node(){        this.id=ID++;    }    public int getId() {        return id;    }         public static void reset(){        ID=0;    }    @Override    public String toString() {        return id+"";    }     }

 

package com.siwanghu.regextoNFA;public class Edge {    private Node begin;    private Node end;    private String label;    private Edge edge;         public Edge() {        super();    }    public Edge(Node begin, Node end) {        super();        this.begin = begin;        this.end = end;    }    public Edge(Node begin, Node end, String label) {        super();        this.begin = begin;        this.end = end;        this.label = label;    }    public String getLabel() {        return label;    }    public void setLabel(String label) {        this.label = label;    }    public Edge getEdge() {        return edge;    }    public void setEdge(Edge edge) {        this.edge = edge;    }         public Node getBegin() {        return begin;    }    public void setBegin(Node begin) {        this.begin = begin;    }    public Node getEnd() {        return end;    }    public void setEnd(Node end) {        this.end = end;    }    @Override    public String toString() {        return "Edge [begin=" + begin + ", end=" + end + ", label=" + label                + "]";    }     }package com.siwanghu.regextoNFA;import java.util.ArrayList;import java.util.List;public class Graph {    private List<Edge> edges;    private Node start;    private Node end;    public Graph() {        edges = new ArrayList<Edge>();    }    public List<Edge> getEdges() {        return edges;    }    public Node getStart() {        return start;    }    public void setStart(Node start) {        this.start = start;    }    public Node getEnd() {        return end;    }    public void setEnd(Node end) {        this.end = end;    }    public void reset() {        Node.reset();    }    public void Star(Object obj) {        if (obj.getClass().getName().equals(Graph.class.getName())) {            addStar((Graph) obj);            return;        }        if (obj.getClass().getName().equals(Character.class.getName())) {            addStar((Character) obj);            return;        } else {            throw new RuntimeException("You have an error in your Regex syntax");        }    }    public void Union(Object obj1, Object obj2) {        if (obj1.getClass().getName().equals(Character.class.getName())) {            if (obj2.getClass().getName().equals(Graph.class.getName())) {                addUnion((Character) obj1, (Graph) obj2);                return;            }            if (obj2.getClass().getName().equals(Character.class.getName())) {                addUnion((Character) obj1, (Character) obj2);                return;            }        }        if (obj1.getClass().getName().equals(Graph.class.getName())) {            if (obj2.getClass().getName().equals(Graph.class.getName())) {                addUnion((Graph) obj1, (Graph) obj2);                return;            }            if (obj2.getClass().getName().equals(Character.class.getName())) {                addUnion((Graph) obj1, (Character) obj2);                return;            }        } else {            throw new RuntimeException("You have an error in your Regex syntax");        }    }    public void Concat(Object obj1, Object obj2) {        if (obj1.getClass().getName().equals(Character.class.getName())) {            if (obj2.getClass().getName().equals(Graph.class.getName())) {                addConcat((Character) obj1, (Graph) obj2);                return;            }            if (obj2.getClass().getName().equals(Character.class.getName())) {                addConcat((Character) obj1, (Character) obj2);                return;            }        }        if (obj1.getClass().getName().equals(Graph.class.getName())) {            if (obj2.getClass().getName().equals(Graph.class.getName())) {                addConcat((Graph) obj1, (Graph) obj2);                return;            }            if (obj2.getClass().getName().equals(Character.class.getName())) {                addConcat((Graph) obj1, (Character) obj2);                return;            }        } else {            throw new RuntimeException("You have an error in your Regex syntax");        }    }    public void addStar(Graph graph) {        Node begNode = new Node();        Node endNode = new Node();        Edge edge1 = new Edge(endNode, begNode, "epsilon");        Edge edge2 = new Edge(begNode, graph.getStart(), "epsilon");        Edge edge3 = new Edge(graph.getEnd(), endNode, "epsilon");        for (int i = 0; i < graph.getEdges().size(); i++) {            this.edges.add(graph.getEdges().get(i));        }        this.edges.add(edge1);        this.edges.add(edge2);        this.edges.add(edge3);        this.start = begNode;        this.end = endNode;    }    public void addStar(Character character) {        Node nodeCenter = new Node();        Node nodebeg = new Node();        Node nodeend = new Node();        Edge edgeLink = new Edge(nodeCenter, nodeCenter, character.toString());        Edge edgeEpsilonBeg = new Edge(nodebeg, nodeCenter, "epsilon");        Edge edgeepsilonEnd = new Edge(nodeCenter, nodeend, "epsilon");        this.edges.add(edgeLink);        this.edges.add(edgeEpsilonBeg);        this.edges.add(edgeepsilonEnd);        this.start = nodebeg;        this.end = nodeend;    }    public void addUnion(Character character, Graph graph) {        Node begNode = new Node();        Node endNode = new Node();        Edge edge1 = new Edge(begNode, graph.getStart(), "epsilon");        Edge edge2 = new Edge(graph.getEnd(), endNode, "epsilon");        Edge edge3 = new Edge(begNode, endNode, character.toString());        for (int i = 0; i < graph.getEdges().size(); i++) {            this.edges.add(graph.getEdges().get(i));        }        this.edges.add(edge1);        this.edges.add(edge2);        this.edges.add(edge3);        this.start = begNode;        this.end = endNode;    }    public void addUnion(Graph graph, Character character) {        Node begNode = new Node();        Node endNode = new Node();        Edge edge1 = new Edge(begNode, graph.getStart(), "epsilon");        Edge edge2 = new Edge(graph.getEnd(), endNode, "epsilon");        Edge edge3 = new Edge(begNode, endNode, character.toString());        for (int i = 0; i < graph.getEdges().size(); i++) {            this.edges.add(graph.getEdges().get(i));        }        this.edges.add(edge1);        this.edges.add(edge2);        this.edges.add(edge3);        this.start = begNode;        this.end = endNode;    }    public void addUnion(Graph graph1, Graph graph2) {        Node begNode = new Node();        Node endNode = new Node();        Edge edge1 = new Edge(begNode, graph1.getStart(), "epsilon");        Edge edge2 = new Edge(begNode, graph2.getStart(), "epsilon");        Edge edge3 = new Edge(graph1.getEnd(), endNode, "epsilon");        Edge edge4 = new Edge(graph2.getEnd(), endNode, "epsilon");        this.start = begNode;        this.end = endNode;        for (int i = 0; i < graph1.getEdges().size(); i++) {            this.edges.add(graph1.getEdges().get(i));        }        for (int i = 0; i < graph2.getEdges().size(); i++) {            this.edges.add(graph2.getEdges().get(i));        }        this.edges.add(edge1);        this.edges.add(edge2);        this.edges.add(edge3);        this.edges.add(edge4);    }    public void addUnion(Character characterOne, Character characterTwo) {        Node nodebeg = new Node();        Node nodeend = new Node();        Edge edgeOne = new Edge(nodebeg, nodeend, characterOne.toString());        Edge edgeTwo = new Edge(nodebeg, nodeend, characterTwo.toString());        edges.add(edgeOne);        edges.add(edgeTwo);        start = nodebeg;        end = nodeend;    }    public void addConcat(Character character, Graph graph) {        Node begNode = new Node();        Edge edge = new Edge(begNode, graph.getStart(), character.toString());        for (int i = 0; i < graph.getEdges().size(); i++) {            this.edges.add(graph.getEdges().get(i));        }        this.edges.add(edge);        this.start = begNode;        this.end = graph.getEnd();    }    public void addConcat(Graph graph, Character character) {        Node endNode = new Node();        Edge edge = new Edge(graph.getEnd(), endNode, character.toString());        for (int i = 0; i < graph.getEdges().size(); i++) {            this.edges.add(graph.getEdges().get(i));        }        this.edges.add(edge);        this.start = graph.getStart();        this.end = endNode;    }    public void addConcat(Graph graph1, Graph graph2) {        Edge edge = new Edge(graph1.getEnd(), graph2.getStart(), "epsilon");        this.start = graph1.getStart();        this.end = graph2.getEnd();        for (int i = 0; i < graph1.getEdges().size(); i++) {            this.edges.add(graph1.getEdges().get(i));        }        for (int i = 0; i < graph2.getEdges().size(); i++) {            this.edges.add(graph2.getEdges().get(i));        }        this.edges.add(edge);    }    public void addConcat(Character characterOne, Character characterTwo) {        Node begNode = new Node();        Node midNode = new Node();        Node endNode = new Node();        Edge edge1 = new Edge(begNode, midNode, characterOne.toString());        Edge edge2 = new Edge(midNode, endNode, characterTwo.toString());        this.start = begNode;        this.end = endNode;        this.edges.add(edge1);        this.edges.add(edge2);    }    @Override    public String toString() {        String printString = "Start=" + this.start + "  End=" + this.end + "\n";        for (int i = 0; i < edges.size(); i++) {            printString += edges.get(i) + "\n";        }        return printString;    }}

 

package com.siwanghu.regextoNFA;import java.util.Stack;public class Regex {    private String regex = "";    private Stack operatorStack;    private Stack operandStack;    private int[][] priority = {            { 1, 1, 1, -1, 1, 1 }, // *&|()#            { -1, 1, 1, -1, 1, 1 }, { -1, -1, 1, -1, 1, 1 },            { -1, -1, -1, -1, 0, 2 }, { 1, 1, 1, 1, 1, 1 },            { -1, -1, -1, -1, -1, -1 } };    public Regex() {        regex = "";        operatorStack = new Stack();        operandStack = new Stack();    }    public Regex(String _regex) {        regex = "";        operatorStack = new Stack();        operandStack = new Stack();        prepareString(_regex);    }    public Graph transformNFA() {        if (regex.length() == 0)            return null;        else {            int i = 0;            operatorStack.push('#');            char[] _regex = (regex + "#").toCharArray();            while (_regex[i] != '#'                    || (Character) (operatorStack.peek()) != '#') {                if (!isOperator(_regex[i])) {                    operandStack.push((Character)_regex[i]);                    i++;                } else {                    int value=priorityOperator((Character)(operatorStack.peek()), _regex[i]);                    switch (value) {                    case 1:                        Character character=(Character)operatorStack.pop();                        switch (character) {                        case '*':                            Object obj=operandStack.pop();                            Graph graph1=new Graph();                            graph1.Star(obj);                            operandStack.push(graph1);                            break;                        case '&':                            Object obj2=operandStack.pop();                            Object obj1=operandStack.pop();                            Graph graph2=new Graph();                            graph2.Concat(obj1, obj2);                            operandStack.push(graph2);                            break;                        case '|':                            Object obj4=operandStack.pop();                            Object obj3=operandStack.pop();                            Graph graph3=new Graph();                            graph3.Union(obj3, obj4);                            operandStack.push(graph3);                            break;                        default:                            break;                        }                        break;                    case 0:                        operatorStack.pop();                        i++;                        break;                    case -1:                        operatorStack.push(_regex[i]);                        i++;                        break;                    default:                        break;                    }                }            }            return (Graph) operandStack.pop();        }    }         public void reset(){        Node.reset();        operandStack.clear();        operatorStack.clear();    }    public String getRegex() {        return regex;    }    public void setRegex(String _regex) {        prepareString(_regex);    }    private boolean isOperator(Character character) {        String operatorString = "*&|()#";        if (operatorString.contains(character.toString())) {            return true;        } else {            return false;        }    }    private int priorityOperator(Character character1, Character character2) {        String priorityString = "*&|()#";        return this.priority[priorityString.indexOf(character1.toString())][priorityString                .indexOf(character2.toString())];    }    private void prepareString(String _regex) {        char[] regexs = _regex.replaceAll(" ", "").toCharArray();        for (int i = 0; i < regexs.length; i++) {            if (i == 0)                regex += regexs[i];            else {                if (regexs[i] == '|' || regexs[i] == '*' || regexs[i] == ')') {                    regex += regexs[i];                } else {                    if (regexs[i - 1] == '(' || regexs[i - 1] == '|')                        regex += regexs[i];                    else                        regex += ("&" + regexs[i]);                }            }        }    }}12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152package com.siwanghu.regextoNFA;public class Test {    public static void main(String[] args) {        try {            String regexString1 = "a*";            Regex regex1 = new Regex(regexString1);            System.out.println(regex1.getRegex());            System.out.println(regex1.transformNFA());            regex1.reset();                         String regexString2 = "ab";            Regex regex2 = new Regex(regexString2);            System.out.println(regex2.getRegex());            System.out.println(regex2.transformNFA());            regex2.reset();                         String regexString3 = "a|b";            Regex regex3 = new Regex(regexString3);            System.out.println(regex3.getRegex());            System.out.println(regex3.transformNFA());            regex3.reset();                         String regexString4 = "(a|b)*";            Regex regex4 = new Regex(regexString4);            System.out.println(regex4.getRegex());            System.out.println(regex4.transformNFA());            regex4.reset();                         String regexString5 = "1(0|1)*101";            Regex regex5 = new Regex(regexString5);            System.out.println(regex5.getRegex());            System.out.println(regex5.transformNFA());            regex5.reset();                         String regexString6 = "0*10*10*10*";            Regex regex6 = new Regex(regexString6);            System.out.println(regex6.getRegex());            System.out.println(regex6.transformNFA());            regex6.reset();                         String regexString7 = "1(1010*|1(010)*1)*0";            Regex regex7 = new Regex(regexString7);            System.out.println(regex7.getRegex());            System.out.println(regex7.transformNFA());            regex6.reset();                     } catch (Exception e) {            System.out.println(e.getMessage());        }    }