org.norecess.citkit.environment
Class NullEnvironment<T>

java.lang.Object
  org.norecess.citkit.environment.NullEnvironment<T>

All Implemented Interfaces:

java.io.Serializable, IEnvironment<T>

public class NullEnvironment<T>
extends java.lang.Object
implements IEnvironment<T>

See Also:

Serialized Form

Constructor Summary

NullEnvironment()

Method Summary

void	add(ISymbol variable, T value) Adds a new variable to the current environment.
Environment<T>	create() Creates a nested environment.
void	define(ISymbol variable, T value) Defines the variable in the top level environment.
boolean	equals(java.lang.Object o)
T	get(ISymbol variable) Returns the value associated with the specified variable.
int	hashCode()
T	set(ISymbol variable, T value) Changes the value associated with the specified variable.
HobbesTIR	setInCurrentScope(ISymbol variable, T value)

Methods inherited from class java.lang.Object

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

Constructor Detail

NullEnvironment

public NullEnvironment()

Method Detail

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

add

public void add(ISymbol variable,
                T value)
         throws InvalidVariableException

Description copied from interface: IEnvironment

Adds a new variable to the current environment. Presently, this does not check the previous environments to see if this shadows an earlier declaration; if this were implemented, it'd be a warning, not an error.

Specified by:

add in interface IEnvironment<T>

Parameters:

variable - the new variable to add to the environment.

value - the new value to associate with the new variable.

Throws:

InvalidVariableException - when the variable is already declared in the current scope.

define

public void define(ISymbol variable,
                   T value)

Description copied from interface: IEnvironment

Defines the variable in the top level environment.

Specified by:

define in interface IEnvironment<T>

Parameters:

variable - the variable to define.

value - the value to set it to.

get

public T get(ISymbol variable)
      throws InvalidVariableException

Description copied from interface: IEnvironment

Returns the value associated with the specified variable. The variable is searched for in all of the previous scopes.

Specified by:

get in interface IEnvironment<T>

Parameters:

variable - the variable to search for.

Returns:

the value associated with the variable.

Throws:

InvalidVariableException - when the variable is undeclared (in this or any previous scope).

set

public T set(ISymbol variable,
             T value)
      throws InvalidVariableException

Description copied from interface: IEnvironment

Changes the value associated with the specified variable. The variable is searched for in all of the previous scopes; the old value is returned.

Specified by:

set in interface IEnvironment<T>

Parameters:

variable - the variable to search for.

value - the new value for the variable.

Returns:

the old value associated with the variable.

Throws:

InvalidVariableException - when the variable is undeclared (in this or any previous scope).

setInCurrentScope

public HobbesTIR setInCurrentScope(ISymbol variable,
                                   T value)
                            throws InvalidVariableException

Throws:

InvalidVariableException

create

public Environment<T> create()

Description copied from interface: IEnvironment

Creates a nested environment.

Specified by:

create in interface IEnvironment<T>