Parser_A

package csc143.data_structures;

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;

/**
 * @author Vita Wiebe
 * @version PA9: Stack/Queue Use, Parser
 * This program takes a mathematical expression, user-input in
 * the standard, infix notation, and produces an equivalent
 * expression written in postfix notation.
 */
public class Parser extends UnboundedArrayQueue implements ParserInterface {

   // Fields

   // String s, the input string from user.
   // Pre-condition: non-empty.
   private String s;

   // Our data structures, for handling the input, reordering,
   // and eventual output of the postfix form of input.
   private UnboundedArrayQueue inputQ;
   private UnboundedArrayQueue outputQ;
   private UnboundedArrayStack transformStack;

   // For comparison when parsing the input string.
   public final String operators = "+-/*%";

   /**
    * Our class constructor.
    */
   public Parser() {
   }

   /**
    * This method parses the input string into individual tokens.
    * <p>
    * For the minimal version of the assignment, this means breaking
    * the input string into single-character tokens, discarding all
    * white space.
    * For the standard version of the assignment, this entails
    * breaking the input string into contiguous "runs" of alphanumeric
    * characters (identifiers and integers) and punctuation (operators).
    * <p>
    * Negative numbers are not handled by this tokenizer.
    *
    * @param input The input string.
    * @return A queue object containing the individual tokens.
    */
   public UnboundedArrayQueue<String> tokenizeInput(String input) {

      s = input;
      String sChar;
      inputQ = new UnboundedArrayQueue();

      // Iterate over input string, s.
      // If not whitespace or operator.
      for(int i = 0; i < s.length(); ) {
         char c = s.charAt(i);
         if (c == ' ') {
            i++;
         } else if (operators.contains(Character.toString(c))) {
            i++;
         } else {
            // will i need to convert to String here too to add to
            // string queue?
            inputQ.add(c);
            i++;
         }
      }

      // Iterate over input string again to find operators.
      // Add these to the inputQ next.
      for(int i = 0; i < s.length(); i++) {
         char c = s.charAt(i);
         if(operators.contains(Character.toString(c))) {
            inputQ.add(c);
         }
      }

   }















}