// Abstract Factory might store a set of Prototypes from which to clone and
// return product objects. [GOF, p126]

public class FactoryProto {

interface Xyz { Xyz cloan(); }

static class Tom implements Xyz {
   public Xyz    cloan()    { return new Tom(); }
   public String toString() { return "ttt"; }
}

static class Dick implements Xyz {
   public Xyz    cloan()    { return new Dick(); }
   public String toString() { return "ddd"; }
}

static class Harry implements Xyz {
   public Xyz    cloan()    { return new Harry(); }
   public String toString() { return "hhh"; }
}

static class Factory {
   private static java.util.Map prototypes = new java.util.HashMap();
   static { prototypes.put( "tom",   new Tom()   );
            prototypes.put( "dick",  new Dick()  );
            prototypes.put( "harry", new Harry() ); }
   public static Xyz makeObject( String s ) {
      return ((Xyz)prototypes.get(s)).cloan();
}  }

public static void main( String[] args ) {
   for (int i=0; i < args.length; i++)
      System.out.print( Factory.makeObject( args[i] ) + "  " );
}}

// D:\Java\patterns> java FactoryProto tom dick tom harry tom
// ttt  ddd  ttt  hhh  ttt



// Purpose.  Prototype design pattern

// 1. Create a "contract" with clone() and getName() entries
// 2. Design a "registry" that maintains a cache of prototypical objects
// 3. Populate the registry with an initializePrototypes() function
// 4. The registry has a findAndClone() "virtual constructor" that can transform
//    a String into its correct object (it calls clone() which then calls "new")
// 5. All classes relate themselves to the clone() contract
// 6. Client uses the findAndClone() virtual ctor instead of the "new" operator

interface Prototype { Object clone();   String getName(); }  // 1. The clone()
interface Command   { void   execute(); }                    //    contract

class PrototypesModule {                  // 2. "registry" of prototypical objs
   private static Prototype[] prototypes = new Prototype[9];
   private static int         total      = 0;
   public static void addPrototype( Prototype obj ) {
      prototypes[total++] = obj;
   }
   public static Object findAndClone( String name ) {  // 4. The "virtual ctor"
      for (int i=0; i < total; i++)
         if (prototypes[i].getName().equals( name ))
            return prototypes[i].clone();
      System.out.println( name + " not found" );
      return null;
}  }
                                                  // 5. Sign-up for the clone()
class This implements Prototype, Command {        //    contract.  Each class 
   public Object clone()   { return new This(); } //    calls "new" on itself
   public String getName() { return "This"; }     //    FOR the client.
   public void   execute() { System.out.println( "This: execute" ); }
}
class That implements Prototype, Command {
   public Object clone()   { return new That(); }
   public String getName() { return "That"; }
   public void   execute() { System.out.println( "That: execute" ); }
}
class TheOther implements Prototype, Command {
   public Object clone()   { return new TheOther(); }
   public String getName() { return "TheOther"; }
   public void   execute() { System.out.println( "TheOther: execute" ); }
}

public class PrototypeDemo {
   public static void initializePrototypes() {    // 3. Populate the "registry"
      PrototypesModule.addPrototype( new This() );
      PrototypesModule.addPrototype( new That() );
      PrototypesModule.addPrototype( new TheOther() );
   }
   public static void main( String[] args ) {
      initializePrototypes();
      Object[] objects = new Object[9];
      int      total   = 0;
      for (int i=0; i < args.length; i++) {     // 6. Client does not use "new"
         objects[total] = PrototypesModule.findAndClone( args[i] );
         if (objects[total] != null) total++; }
      for (int i=0; i < total; i++) ((Command)objects[i]).execute();
}  }

// C:> java PrototypeDemo Garbage This That Nothing TheOther
// Garbage not found
// Nothing not found
// This: execute
// That: execute
// TheOther: execute