package username.functions;

/**
 * Functions that represent that composition
 * E.g., f(x) = g(h(x))
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of April 2006
 */
public class ComposeUIF
  implements UnaryIntegerFunction
{

// +--------+-----------------------------------------------
// | Fields |
// +--------+

  /** The outer function in the composition (g in g(h(x))). */
  UnaryIntegerFunction outer;
  /** The inner function in the composition (h in g(h(x))). */
  UnaryIntegerFunction inner;


// +--------------+-----------------------------------------
// | Constructors |
// +--------------+

  /** Build a new function that returns f1(f2(x)). */
  public ComposeUIF(UnaryIntegerFunction f1, UnaryIntegerFunction f2)
  {
    this.outer = f1;
    this.inner = f2;
  } // ComposeUIF(UnaryIntegerFunction,UnaryIntegerFunction)

// +------------------+-------------------------------------
// | Standard Methods |
// +------------------+

  public String toString() 
  {
    StringBuffer str1 = new StringBuffer(outer.toString());
    String str2 = inner.toString();

    int xpos;
    // Put a special character in for each x to prepare for replacement.
    // (We're going to put str2 in for each x, but since it may contain
    // x, we need to do so indirectly.)
    while ((xpos = str1.indexOf("x")) >= 0) {
      str1.replace(xpos, xpos+1, "@");
    } // while
    while ((xpos = str1.indexOf("@")) >= 0) {
      str1.replace(xpos, xpos+1, str2);
    } // while

    return str1.toString();
  } // toString

// +----------------+---------------------------------------
// | Public Methods |
// +----------------+

  public int apply(int x)
  {
    return this.outer.apply(this.inner.apply(x));
  } // apply(int)

} // ComposeUIF