jsint
Class LexicalEnvironment

java.lang.Object
  |
  +--jsint.LexicalEnvironment

All Implemented Interfaces:

java.io.Serializable

public class LexicalEnvironment

extends java.lang.Object

implements java.io.Serializable

Environments store mappings from symbols to locations. At compile time, we can lookup to see if a symbol names a location, and at run time we can get or set the value in a location.

Author:

Peter Norvig, Copyright 1998, peter@norvig.com, license subsequently modified by Jscheme project members licensed under zlib licence (see license.txt)

See Also:

Serialized Form

Field Summary

static LexicalEnvironment

NULLENV The global environment.

Constructor Summary

LexicalEnvironment(java.lang.Object vars, java.lang.Object[] vals, LexicalEnvironment parent)
Create an LexicalEnvironment with local variables and values, and a parent LexicalEnvironment.

LexicalEnvironment(java.lang.Object vars, java.lang.Object[] vals, LexicalEnvironment parent, boolean isNullEnv)

Method Summary

java.lang.Object	get(LocalVariable var) Get the value of the LocalVariable in this LexicalEnvironment.
LocalVariable	lookup(Symbol var)
LocalVariable	lookup(Symbol var, int up, int in, java.lang.Object vars) Lookup the symbol in the environment.
java.lang.Object	set(LocalVariable var, java.lang.Object newVal) Set the value of the LocalVariable in this LexicalEnvironment to a new value.
void	show(java.io.PrintWriter s)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

NULLENV

public static final LexicalEnvironment NULLENV

The global environment. All info is in the Symbols themselves.

Constructor Detail

LexicalEnvironment

public LexicalEnvironment(java.lang.Object vars,
                          java.lang.Object[] vals,
                          LexicalEnvironment parent)

Create an LexicalEnvironment with local variables and values, and a parent LexicalEnvironment.

LexicalEnvironment

public LexicalEnvironment(java.lang.Object vars,
                          java.lang.Object[] vals,
                          LexicalEnvironment parent,
                          boolean isNullEnv)

Method Detail

lookup

public LocalVariable lookup(Symbol var)

lookup

public LocalVariable lookup(Symbol var,
                            int up,
                            int in,
                            java.lang.Object vars)

Lookup the symbol in the environment. Return either a LocalVariable a Symbol representing the global variable.

get

public java.lang.Object get(LocalVariable var)

Get the value of the LocalVariable in this LexicalEnvironment.

set

public java.lang.Object set(LocalVariable var,
                            java.lang.Object newVal)

Set the value of the LocalVariable in this LexicalEnvironment to a new value.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

show

public void show(java.io.PrintWriter s)