Package org.moeaframework.core.variable

Class Program

java.lang.Object

org.moeaframework.util.tree.Node

org.moeaframework.core.variable.Program

All Implemented Interfaces:

Serializable, Variable

public class Program
extends Node
implements Variable

A decision variable for programs. The program is represented as a strongly-typed expression tree.

Note: Although Program extends Node, the Program object must never be altered by the optimization algorithm. Only its arguments can undergo variation.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
Program(Rules rules)	Constructs a new program variable with the specified syntax rules.

Method Summary

Modifier and Type	Method	Description
Program	copy()	Returns an independent copy of this decision variable.
Program	copyNode()	Returns a copy of this node, but without any children or parents assigned.
void	decode(String value)	Parses and loads the value of this variable from a string.
String	encode()	Encodes the value of this variable as a string.
Object	evaluate(Environment environment)	Evaluates this node in the context of the specified environment.
Rules	getRules()	Returns the rules defining the program syntax.
void	randomize()	Initializes the program tree using ramped half-and-half initialization.

Methods inherited from class org.moeaframework.util.tree.Node

copyTree, getArgument, getArgumentType, getDepth, getFunctionAt, getFunctionAt, getMaximumHeight, getMinimumHeight, getNodeAt, getNodeAt, getNodeAt, getNumberOfArguments, getNumberOfFunctions, getNumberOfFunctions, getNumberOfNodes, getNumberOfNodes, getNumberOfNodes, getNumberOfTerminals, getNumberOfTerminals, getParent, getReturnType, getTerminalAt, getTerminalAt, isFixed, isTerminal, isValid, setArgument, setFixed, setFixedTree, size, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.moeaframework.core.Variable

toString

Constructor Details

Program

public Program(Rules rules)

Constructs a new program variable with the specified syntax rules.

Parameters:

rules - the rules defining the program syntax

Method Details

getRules

public Rules getRules()

Returns the rules defining the program syntax.

Returns:

the rules defining the program syntax

copy

public Program copy()

Description copied from interface: Variable

Returns an independent copy of this decision variable. It is required that x.copy() is completely independent from x. This means any method invoked on x.copy() in no way alters the state of x and vice versa. It is typically the case that x.copy().getClass() == x.getClass() and x.copy().equals(x).

Specified by:

copy in interface Variable

Returns:

an independent copy of this decision variable

copyNode

public Program copyNode()

Description copied from class: Node

Returns a copy of this node, but without any children or parents assigned.

Specified by:

copyNode in class Node

Returns:

a copy of this node, but without any children or parents assigned

evaluate

public Object evaluate(Environment environment)

Description copied from class: Node

Evaluates this node in the context of the specified environment.

Specified by:

evaluate in class Node

Parameters:

environment - the execution environment

Returns:

the result of evaluating this node

randomize

public void randomize()

Initializes the program tree using ramped half-and-half initialization.

Specified by:

randomize in interface Variable

encode

public String encode()

Description copied from interface: Variable

Encodes the value of this variable as a string. This should reflect the internal representation of the value and not necessarily the actual value. For example, a binary-encoded integer should display the bits and not the integer value. Implementations should make an effort to display the value in a meaningful format, but that is not required. Instead, use Variable.toString() if a human-readable format is required. This method along with Variable.decode(String) are used primarily for storing values in text files. To make parsing easier, the resulting string must: 1. Only contain ASCII characters 2. Contain no whitespace (no spaces, tabs, newlines, etc.)

Specified by:

encode in interface Variable

Returns:

the encoded value as a string

decode

public void decode(String value)

Description copied from interface: Variable

Parses and loads the value of this variable from a string. This must be able to process any string produced by Variable.encode().

Specified by:

decode in interface Variable

Parameters:

value - the value as a string