orc.runtime.nodes
Class Defs

java.lang.Object
  orc.runtime.nodes.Node
      orc.runtime.nodes.Defs

All Implemented Interfaces:

java.io.Serializable

public class Defs
extends Node

See Also:

Serialized Form

Field Summary

java.util.List<Def>	defs
java.util.Set<Var>	freeset
Node	next

Constructor Summary

Defs(java.util.List<Def> defs, Node next, java.util.Set<Var> freeset)

Method Summary

void	process(Token t) Creates closures encapsulating the definitions and the defining environment.

Methods inherited from class java.lang.Object

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

Field Detail

defs

public java.util.List<Def> defs

next

public Node next

freeset

public java.util.Set<Var> freeset

Constructor Detail

Defs

public Defs(java.util.List<Def> defs,
            Node next,
            java.util.Set<Var> freeset)

Method Detail

process

public void process(Token t)

Creates closures encapsulating the definitions and the defining environment. The environment for the closure is the same as the input environment, but it is extended to include a binding for the definition name whose value is the closure. This means that the closure environment must refer to the closure, so there is a cycle in the object pointer graph. This cycle is constructed in three steps:

Create the closure with a null environment

Bind the name to the new closure

Update the closure to point to the new environment Then the next token is activated in this new environment. This is a standard technique for creating recursive closures. Closures created in this way are protected by a PartialValue object, preventing them from being used in argument position until all unbound vars in all definition bodies become bound.

Specified by:

process in class Node

Parameters:

t - input token being processed