ec.gp

Class ADFStack

java.lang.Object

ec.gp.ADFStack

All Implemented Interfaces:

Prototype, Setup, Serializable, Cloneable

public class ADFStack
extends Object
implements Prototype

ADFStack is a special data object used to hold ADF data. This object is a weird beast and takes some explaining. It consists of a main stack, a secondary "substack", and a "reserve" area (also implemented as a stack, but it doesn't have to be). The reserve is used to "recycle" objects rather than having to create then new every time.

When an ADF is evaluated, it first evaluates its children, then it calls push() on the ADFstack. push() either creates a new ADFContext, or it fetches one from the reserve if possible. It then pushes the context on the main stack, and also returns the context. The ADF fills the context's arguments with the results of its childrens' evaluation, and sets numargs to the number of arguments, then evaluates the ADF's associated function tree,

When an ADM is evaluated, it calls push() on the ADFstack. The ADM then fills the context's adm node with itself, and sets numargs to the number of children it has. Then it calls the ADM's associated function tree.

In that tree, if an argument terminal of value n is evaluated, the argument terminal calls evaluate(...) on the top context on the ADF stack and returns the result. This method does different things depending on whether the top context represented an ADF or an ADM. If it was an ADF, the context simply sets input to the value of argument n in the context's argument list, and returns input. If it was an ADM, the context pops itself off the stack and pushes itself on the substack (to set up the right context for evaluating an original child of the ADM), then evaluates child n of the ADM, then pops itself off the substack and pushes itself back on the stack to restore the context. Input is set to the evaluated results, and input is returned.

Parameters

base.context classname, inherits and != ec.gp.GPContext

(the stack's GPContext class)

Parameters
gp.adf-stack

Parameter bases

base.context

(context_proto)

Version:

1.0

Author:

Sean Luke

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
ADFContext	context_proto
static int	INITIAL_STACK_SIZE
protected int	inReserve
protected int	onStack
protected int	onSubstack
static String	P_ADF
static String	P_ADFSTACK
static String	P_CONTEXT
protected ADFContext[]	reserve
private static long	serialVersionUID
protected ADFContext[]	stack
protected ADFContext[]	substack

Constructor Summary

Constructors

Constructor and Description
ADFStack()

Method Summary

Modifier and Type	Method and Description
Object	clone() Creates a new individual cloned from a prototype, and suitable to begin use in its own evolutionary context.
Parameter	defaultBase() Returns the default base for this prototype.
ADFContext	get() Returns an ADFContext from the stack's reserve, or creates one fresh if there are none in reserve.
int	moveFromSubstack(int n) Moves n items onto the stack (popss them off the substack and pushes them onto the stack).
int	moveOntoSubstack(int n) Moves n items onto the substack (pops them off the stack and pushes them onto the substack).
int	pop(int n) Pops off n items from the stack, if possible.
ADFContext	push(ADFContext obj) Pushes an ADFContext onto the main stack.
void	reset() Pops off all items on the stack and the substack.
void	setup(EvolutionState state, Parameter base) Sets up the object by reading it from the parameters stored in state, built off of the parameter base base.
ADFContext	top(int n) Returns the nth item in the stack (0-indexed), or null if this goes to the bottom of the stack.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

P_ADFSTACK

public static final String P_ADFSTACK

See Also:

Constant Field Values

P_ADF

public static final String P_ADF

See Also:

Constant Field Values

P_CONTEXT

public static final String P_CONTEXT

See Also:

Constant Field Values

context_proto

public ADFContext context_proto

INITIAL_STACK_SIZE

public static final int INITIAL_STACK_SIZE

See Also:

Constant Field Values

onStack

protected int onStack

onSubstack

protected int onSubstack

inReserve

protected int inReserve

stack

protected ADFContext[] stack

substack

protected ADFContext[] substack

reserve

protected ADFContext[] reserve

Constructor Detail

ADFStack

public ADFStack()

Method Detail

defaultBase

public Parameter defaultBase()

Description copied from interface: Prototype

Returns the default base for this prototype. This should generally be implemented by building off of the static base() method on the DefaultsForm object for the prototype's package. This should be callable during setup(...).

Specified by:

defaultBase in interface Prototype

setup

public void setup(EvolutionState state,
                  Parameter base)

Description copied from interface: Prototype

Sets up the object by reading it from the parameters stored in state, built off of the parameter base base. If an ancestor implements this method, be sure to call super.setup(state,base); before you do anything else.

For prototypes, setup(...) is typically called once for the prototype instance; cloned instances do not receive the setup(...) call. setup(...) may be called more than once; the only guarantee is that it will get called at least once on an instance or some "parent" object from which it was ultimately cloned.

Specified by:

setup in interface Prototype

Specified by:

setup in interface Setup

clone

public Object clone()

Description copied from interface: Prototype

Creates a new individual cloned from a prototype, and suitable to begin use in its own evolutionary context.

Typically this should be a full "deep" clone. However, you may share certain elements with other objects rather than clone hem, depending on the situation:

• If you hold objects which are shared with other instances, don't clone them.
• If you hold objects which must be unique, clone them.
• If you hold objects which were given to you as a gesture of kindness, and aren't owned by you, you probably shouldn't clone them.
• DON'T attempt to clone: Singletons, Cliques, or Populations, or Subpopulation.
• Arrays are not cloned automatically; you may need to clone an array if you're not sharing it with other instances. Arrays have the nice feature of being copyable by calling clone() on them.

Implementations.

• If no ancestor of yours implements clone(), and you have no need to do clone deeply, and you are abstract, then you should not declare clone().
• If no ancestor of yours implements clone(), and you have no need to do clone deeply, and you are not abstract, then you should implement it as follows:

   public Object clone() 
       {
       try
           { 
           return super.clone();
           }
       catch ((CloneNotSupportedException e)
           { throw new InternalError(); } // never happens
       }
          

• If no ancestor of yours implements clone(), but you need to deep-clone some things, then you should implement it as follows:

   public Object clone() 
       {
       try
           { 
           MyObject myobj = (MyObject) (super.clone());
  
           // put your deep-cloning code here...
           }
       catch ((CloneNotSupportedException e)
           { throw new InternalError(); } // never happens
       return myobj;
       } 
          

• If an ancestor has implemented clone(), and you also need to deep clone some things, then you should implement it as follows:

   public Object clone() 
       { 
       MyObject myobj = (MyObject) (super.clone());
  
       // put your deep-cloning code here...
  
       return myobj;
       } 
          

Specified by:

clone in interface Prototype

Overrides:

clone in class Object

get

public final ADFContext get()

Returns an ADFContext from the stack's reserve, or creates one fresh if there are none in reserve. While you can throw this ADFContext away if you like, it'd be good if you actually didn't call this function unless you expected to push the context onto the stack with push(ADFContext obj) -- karma!

push

public final ADFContext push(ADFContext obj)

Pushes an ADFContext onto the main stack. The best way to get an ADFContext to push onto the stack is with get(). Returns obj.

pop

public final int pop(int n)

Pops off n items from the stack, if possible. Returns the number of items actually popped off.

top

public final ADFContext top(int n)

Returns the nth item in the stack (0-indexed), or null if this goes to the bottom of the stack.

moveOntoSubstack

public final int moveOntoSubstack(int n)

Moves n items onto the substack (pops them off the stack and pushes them onto the substack). Returns the actual number of items for which this was done.

moveFromSubstack

public final int moveFromSubstack(int n)

Moves n items onto the stack (popss them off the substack and pushes them onto the stack). Returns the actual number of items moved from the Substack onto the main stack

reset

public final void reset()

Pops off all items on the stack and the substack.