g2d.jlambda

Class Closure

java.lang.Object

g2d.jlambda.Closure

public final class Closure
extends java.lang.Object

This class corresponds to a Lisp or Scheme style closure. Evaluation of a lambda expression

 (lambda (var_1 ... var_N) exp)
 

returns a instance of the Closure consisting of its arity N, the current lexical environment, and the body exp. It has convenience methods that allow a closure to be applied to a sequence of values. Closures are used heavily in event handling in the g2d.glyph package.

Since:

July 10th, 2004

Author:

Ian A. Mason.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Closure(int arity, java.lang.Object body, Environment env, g2d.jlambda.Continuation k, Interpreter engine) Constructs a Closure object.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	applyClosure() A convenience method.
java.lang.Object	applyClosure(java.lang.Object arg0) A convenience method.
java.lang.Object	applyClosure(java.lang.Object arg0, java.lang.Object arg1) A convenience method.
java.lang.Object	applyClosure(java.lang.Object arg0, java.lang.Object arg1, java.lang.Object arg2) A convenience method.
java.lang.Object	applyClosure(java.lang.Object arg0, java.lang.Object arg1, java.lang.Object arg2, java.lang.Object arg3) A convenience method.
java.lang.Object	applyClosure(java.lang.Object arg0, java.lang.Object arg1, java.lang.Object arg2, java.lang.Object arg3, java.lang.Object arg4) A convenience method.
int	getArity() Returns the closure's arity.
protected java.lang.Object	getBody() Returns the closure's body.
protected Environment	getEnv() Returns the closure's environment.
java.lang.String	toString() A string representation of the closure.

Methods inherited from class java.lang.Object

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

Constructor Detail

Closure

protected Closure(int arity,
                  java.lang.Object body,
                  Environment env,
                  g2d.jlambda.Continuation k,
                  Interpreter engine)
           throws EvaluateError

Constructs a Closure object.

Parameters:

arity - an int specifying the arity of the closure. Thunks, zero arity closures, are allowed. Negative arities are not allowed.

body - an Object representing the body of the closure.

env - an Environment object representing the environment of the closure.

k - a Continuation object, used for providing information if an exception

engine - the interpreter (namespace) that the cosure belongs to. needs to be throw.

Throws:

EvaluateError - in the case the the airty is negative, or the environment is null.

Method Detail

toString

public java.lang.String toString()

A string representation of the closure.

Overrides:

toString in class java.lang.Object

getBody

protected java.lang.Object getBody()

Returns the closure's body.

Returns:

the body.

getEnv

protected Environment getEnv()

Returns the closure's environment.

Returns:

the environment.

getArity

public int getArity()

Returns the closure's arity.

Returns:

the arity.

applyClosure

public java.lang.Object applyClosure()

A convenience method. It applies the closure (a thunk). Thus is an entry point to the JLambda interpreter.

Returns:

the result computed by the interpreter.

applyClosure

public java.lang.Object applyClosure(java.lang.Object arg0)

A convenience method. It applies the closure to the argument(s) provided. Thus is an entry point to the JLambda interpreter.

Parameters:

arg0 - the first argument to the closure.

Returns:

the result computed by the interpreter.

applyClosure

public java.lang.Object applyClosure(java.lang.Object arg0,
                                     java.lang.Object arg1)

A convenience method. It applies the closure to the argument(s) provided. Thus is an entry point to the JLambda interpreter.

Parameters:

arg0 - the first argument to the closure.

arg1 - the second argument to the closure.

Returns:

the result computed by the interpreter.

applyClosure

public java.lang.Object applyClosure(java.lang.Object arg0,
                                     java.lang.Object arg1,
                                     java.lang.Object arg2)

A convenience method. It applies the closure to the argument(s) provided. Thus is an entry point to the JLambda interpreter.

Parameters:

arg0 - the first argument to the closure.

arg1 - the second argument to the closure.

arg2 - the third argument to the closure.

Returns:

the result computed by the interpreter.

applyClosure

public java.lang.Object applyClosure(java.lang.Object arg0,
                                     java.lang.Object arg1,
                                     java.lang.Object arg2,
                                     java.lang.Object arg3)

A convenience method. It applies the closure to the argument(s) provided. Thus is an entry point to the JLambda interpreter.

Parameters:

arg0 - the first argument to the closure.

arg1 - the second argument to the closure.

arg2 - the third argument to the closure.

arg3 - the fourth argument to the closure.

Returns:

the result computed by the interpreter.

applyClosure

public java.lang.Object applyClosure(java.lang.Object arg0,
                                     java.lang.Object arg1,
                                     java.lang.Object arg2,
                                     java.lang.Object arg3,
                                     java.lang.Object arg4)

A convenience method. It applies the closure to the argument(s) provided. Thus is an entry point to the JLambda interpreter.

Parameters:

arg0 - the first argument to the closure.

arg1 - the second argument to the closure.

arg2 - the third argument to the closure.

arg3 - the fourth argument to the closure.

arg4 - the fifth argument to the closure.

Returns:

the result computed by the interpreter.