package cz.cuni.amis.utils;
   
   /**
    * This class is meant for counting hash codes from any possible type.
    * It declares a two heavily overloaded methods ;-).
    * 
    * 1) hash(whatever) -> returns hash number for 'whatever' (of whatever type)
    * 2) add(whatever)  -> add number to the hashCode for 'whatever' (of whatever type)
    * 
   * Typical usage: 
   * 
   * Usualy you will create a method private countHashCode() which you will call from
   * within the constructors after you've initialized variables from which you want
   * to count the hash code. It will look like this:
   * 
   * private int getHashCode(){
   * 	 HashCode hc = new HashCode(); // creating new HashCode instance
   * 	 hc.add(myFirstIntValue);      // adding first parametr to hash code
   *   hc.add(mySecondIntValue);     // second...
   *   hc.add(myFloatValue);         // third...
   *   return hc.getHash();          // returning the hash
   * }
   * 
   * private final int hashCode;
   * 
   * public int ConstrucotrOfMyClass(){
   *   // initializing variables		
   *   hashCode = getHashCode();
   * }
   * 
   * public int hashCode(){
   * 	 return hashCode;
   * }
   * 
   */
  public final class HashCode {
  	
  	public int hash(boolean b){
  		return b ? 0 : 1;
  	}
  	
  	public int hash(byte b){
  		return (int) b;
  	}
  	
  	public int hash(char c){
  		return (int) c;
  	}
  	
  	public int hash(short s){
  		return (int) s;
  	}
  	
  	public int hash(int i){
  		return (int) i;
  	}
  	
  	public int hash(long i){
  		return (int) i;
  	}
  	
  	public int hash(float f){
  		return Float.floatToIntBits(f);
  	}
  	
  	public int hash(double d){		
  		long l = Double.doubleToLongBits(d);
  		return (int)(l ^ (l >>> 32));
  	}
  	
  	public int hash(Object o){
  		return  o == null ? 0 : o.hashCode();
  	}
  	
  	private int hashCode;
  	
  	public HashCode(){
  		hashCode = 17;
  	}
  		
  	private HashCode addNumber(int number){
  		hashCode = 37 * hashCode + number;
  		return this;
  	}
  	
  	public HashCode add(boolean b){
  		addNumber(hash(b));
  		return this;
  	}
  	
  	public HashCode add(byte b){
  		addNumber(hash(b));
  		return this;
  	}
  	
  	public HashCode add(char c){
  		addNumber(hash(c));
  		return this;
  	}
 	
 	public HashCode add(short s){
 		addNumber(hash(s));
 		return this;
 	}
 	
 	public HashCode add(int i){
 		addNumber(hash(i));
 		return this;
 	}
 	
 	public HashCode add(long l){
 		addNumber(hash(l));
 		return this;
 	}
 	
 	public HashCode add(float f){
 		addNumber(hash(f));
 		return this;
 	}
 	
 	public HashCode add(double d){
 		addNumber(hash(d));
 		return this;
 	}
 	
 	public HashCode add(Object o){
 		addNumber(hash(o));
 		return this;
 	}
 	
 	public int getHash(){
 		return hashCode;
 	}
 
 }