slogo.expression

Class VariableFactory

java.lang.Object

slogo.expression.VariableFactory

All Implemented Interfaces:

Context

public class VariableFactory
extends java.lang.Object
implements Context

Clients can use this class to obtain a unique variable per identifier (avoiding a proliferation of objects)

Field Summary

Fields

Modifier and Type	Field and Description
private static VariableFactory	ourInstance
static java.util.Map<java.lang.String,Variable>	varnameToVariable

Constructor Summary

Constructors

Modifier	Constructor and Description
private	VariableFactory()

Method Summary

Modifier and Type	Method and Description
static VariableFactory	getInstance() There should only be one VariableFactory
static Variable	getVariable(IdentifierToken idToken) Determines the variable represented by the given id
static java.util.Map<java.lang.String,Variable>	getVariables()
java.lang.Object	value(java.lang.String name) If there are local/global variables, a variable might have a different value depending on the Context, so Contexts should support determining the value of an identifier.

Methods inherited from class java.lang.Object

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

Field Detail

ourInstance

private static VariableFactory ourInstance

varnameToVariable

public static java.util.Map<java.lang.String,Variable> varnameToVariable

Constructor Detail

VariableFactory

private VariableFactory()

Method Detail

getInstance

public static VariableFactory getInstance()

There should only be one VariableFactory

Returns:

the variable factory

getVariable

public static Variable getVariable(IdentifierToken idToken)

Determines the variable represented by the given id

Parameters:

idToken - - an identifier token

Returns:

the variable that maps to this id token

getVariables

public static java.util.Map<java.lang.String,Variable> getVariables()

value

public java.lang.Object value(java.lang.String name)

Description copied from interface: Context

If there are local/global variables, a variable might have a different value depending on the Context, so Contexts should support determining the value of an identifier.

Specified by:

value in interface Context

Parameters:

name - identifier being evaluated in this Context

Returns:

the object mapped to by the identifier in this Context AKA return the object that the identifier maps to in this context