jsint
Class Symbol

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

All Implemented Interfaces:

SchemeSymbol, java.io.Serializable

public class Symbol

extends java.lang.Object

implements java.io.Serializable, SchemeSymbol

In Jscheme 1.0 to 1.4, symbols were implemented as Strings. In 1.5, we add a Symbol class, with a field for the global value. This makes global lookup faster, but limits us to only one global environment.

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 Symbol	BEGIN
static Symbol	CAR
static Symbol	CDR
static Symbol	DEFINE
static Symbol	IF
static Symbol	LAMBDA
static Symbol	MACRO
static Symbol	NEWLINE
static Symbol	NULL
static Symbol	OR
static Symbol	PACKAGE
static Symbol	QUASIQUOTE
static Symbol	QUOTE
static Symbol	SET
static Symbol	SPACE
static java.util.Hashtable	symbolTable The symbolTable keeps a unique mapping from String name to Symbol.
static Symbol	UNQUOTE
static Symbol	UNQUOTE_SPLICING

Method Summary

java.lang.Object	getGlobalValue() Getting the value of an undefined SchemeSymbol throws a SchemeException
static Symbol	intern(java.lang.String name) Intern a string: look up or make a symbol.
boolean	isDefined() SchemeSymbols are initially undefined.
java.lang.Object	setGlobalValue(java.lang.Object newval) The value can be set to anything
java.lang.String	toString() A symbol can be printed using its name.

Methods inherited from class java.lang.Object

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

Field Detail

symbolTable

public static final java.util.Hashtable symbolTable

The symbolTable keeps a unique mapping from String name to Symbol.

BEGIN

public static final Symbol BEGIN

CAR

public static final Symbol CAR

CDR

public static final Symbol CDR

DEFINE

public static final Symbol DEFINE

IF

public static final Symbol IF

LAMBDA

public static final Symbol LAMBDA

MACRO

public static final Symbol MACRO

NEWLINE

public static final Symbol NEWLINE

NULL

public static final Symbol NULL

OR

public static final Symbol OR

QUASIQUOTE

public static final Symbol QUASIQUOTE

QUOTE

public static final Symbol QUOTE

SET

public static final Symbol SET

SPACE

public static final Symbol SPACE

UNQUOTE

public static final Symbol UNQUOTE

UNQUOTE_SPLICING

public static final Symbol UNQUOTE_SPLICING

PACKAGE

public static final Symbol PACKAGE

Method Detail

intern

public static Symbol intern(java.lang.String name)

Intern a string: look up or make a symbol.

toString

public java.lang.String toString()

A symbol can be printed using its name. We don't do escape processing.

Overrides:

toString in class java.lang.Object

getGlobalValue

public java.lang.Object getGlobalValue()

Description copied from interface: SchemeSymbol

Getting the value of an undefined SchemeSymbol throws a SchemeException

Specified by:

getGlobalValue in interface SchemeSymbol

setGlobalValue

public java.lang.Object setGlobalValue(java.lang.Object newval)

Description copied from interface: SchemeSymbol

The value can be set to anything

Specified by:

setGlobalValue in interface SchemeSymbol

isDefined

public boolean isDefined()

Description copied from interface: SchemeSymbol

SchemeSymbols are initially undefined.

Specified by:

isDefined in interface SchemeSymbol