/**
 * CSE 373, Winter 2011, Jessica Miller
 * This program checks that the parentheses and curly brackets in a String are matching.
 */
import java.io.FileNotFoundException;
import java.util.Stack;

public class SymbolsChecker {
    public static void main(String[] args) throws FileNotFoundException {
        String test1 = "()";
        String test2 = "{}";
        String test3 = "{()}";
        String test4 = "()(){}{}";
        String test5 = "public static void echo(int x) { System.out.print(x) };";
        
        String test6 = "(()";
        String test7 = "{}}";
        String test8 = "({)}";
        String test9 = "public void echo(int x) { System.out.print(x) ;";
        
        System.out.println(test1 + " balanced? " + symbolsMatch(test1));
        System.out.println(test2 + " balanced? " + symbolsMatch(test2));
        System.out.println(test3 + " balanced? " + symbolsMatch(test3));
        System.out.println(test4 + " balanced? " + symbolsMatch(test4));
        System.out.println(test5 + " balanced? " + symbolsMatch(test5));
        System.out.println(test6 + " balanced? " + symbolsMatch(test6));
        System.out.println(test7 + " balanced? " + symbolsMatch(test7));
        System.out.println(test8 + " balanced? " + symbolsMatch(test8));
        System.out.println(test9 + " balanced? " + symbolsMatch(test9));
                
    }

    public static boolean symbolsMatch(String str) {
        Stack<Character> symbolsStack = new Stack<Character>();
        
        for (int i = 0; i < str.length(); i++) {
            char nextToken = str.charAt(i);
            
            if (nextToken == '{' || nextToken == '(') {
                symbolsStack.push(nextToken);
            } else if ((nextToken == '}') && (symbolsStack.isEmpty() || symbolsStack.pop() != '{')) {
                return false;
            } else if ((nextToken == ')') && (symbolsStack.isEmpty() || symbolsStack.pop() != '(')) {
                return false;
            }
        }
        
        return symbolsStack.isEmpty();
    }
}