/** PolynomialD0.java defines a degree 0 polynomial.
 *  Author:  Joel C. Adams
 *  Version: For Java: An Introduction to Computing 1/e.  All Rights Reserved.
 */

package ann.math.polynomial;

import java.util.StringTokenizer;
import ann.util.Controller;

public class PolynomialD0 extends Object
{
 /** Default constructor
  *  Postcondition: myA == 0.0.
  */
 public PolynomialD0()
 {
   myA = 0.0;
 }

 /** Construct from double
  *  Receive:       double aValue.
  *  Postcondition: myA == aValue.
  */
 public PolynomialD0(double aValue)
 {
   myA = aValue;
 }

 /** Construct from String
  *  Receive:       StringBuffer polyString.
  *  Precondition:  polyString is of the form "a",
  *                   where a is a numeric value.
  *  Postcondition: myA == a && a has been removed from polyString.
  */
 public PolynomialD0(String polyString)
 {
   // myTokenizer = new StringTokenizer(polyString);
   myBuffer = new StringBuffer(polyString);
   myA = getNextCoefficient();
 }

  /** utility to extract coefficient from a polynomial string
   *  Receive: int degree, the degree of the polynomial;
   *            String polyString, the String containing the polynomial.
   *  Return:  the coefficient for degree from within polyString.
   */                    
 protected double getNextCoefficient()
 {
   int start = 0;
   boolean negative = false;
   while (start < myBuffer.length()
          && !Character.isDigit(myBuffer.charAt(start))
          && myBuffer.charAt(start) != '.')
   {
     if (myBuffer.charAt(start) == '-')
        negative = true;
     start++;
   }

   int end = start + 1;
   while (end < myBuffer.length()
         && (Character.isDigit(myBuffer.charAt(end))
             || myBuffer.charAt(end) == '.'
             || myBuffer.charAt(end) == 'e'
             || myBuffer.charAt(end) == 'E'))
     end++;

   double result = Double.parseDouble(myBuffer.substring(start,end));
   myBuffer.delete(0, end+1);

   if (negative)
     return -result;
   else
     return result;
  }   

 /** A-attribute accessor
  *  Return: myA.
  */
 public double getA()
 {
   return myA;
 }

 /** A-attribute mutator
  *  Receive:       double newA.
  *  Postcondition: myA == newA.
  */
 public void setA(double newA)
 {
   myA = newA;
 }

 /** String converter (output)
  *  Return: the String equivalent to myA.
  */
 public String toString()
 {
   return Double.toString(myA);
 }

 //--- Attribute variable ---
 private double myA;
 private StringBuffer myBuffer;
}