CSE420 Lab01

package javaapplication2;

import java.io.File;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Scanner;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class JavaApplication2 {

    public static void main(String[] args) {
        System.out.println("Keywords : "+Arrays.toString(keyword("int|float|if|else").toArray()));
        System.out.println("Math Operators : "+Arrays.toString(keyword("[+\\-*=]").toArray()));
        System.out.println("Logical Operators : "+Arrays.toString(keyword("[<>]").toArray()));
        System.out.println("Numerical Values : "+Arrays.toString(keyword("\\d+(\\.\\d+)?").toArray()));
        System.out.println("Others : "+Arrays.toString(keyword("[(){}]").toArray()));

        Set set = keyword("[a-zA-Z0-9]{1,31}");
        Iterator<String> s = keyword("[a-zA-Z0-9]{1,31}").iterator();
        while(s.hasNext()){
            String str = s.next();
            if(str.matches("int|float|if|else|[0-9]+")){
                set.remove(str);
            }
        }
        System.out.println("Identifiers: "+Arrays.toString(set.toArray()));
    }

    public static Set keyword(String pattern){
        Set keyword = new HashSet<>();

        try {
           Scanner sc = new Scanner(new File("a.txt"));

            while(sc.hasNextLine()){
                Pattern patt = Pattern.compile(pattern);

                String s = sc.nextLine();

                Matcher match = patt.matcher(s);

                while(match.find()){
                    keyword.add(match.group());
                }

            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return keyword;
    }
}