danbikel.lisp
Class StringSymbol

java.lang.Object
  danbikel.lisp.Sexp
      danbikel.lisp.Symbol
          danbikel.lisp.StringSymbol

All Implemented Interfaces:

Externalizable, Serializable

public class StringSymbol
extends Symbol
implements Externalizable

StringSymbol objects associate strings with unique references. This association is maintained in Symbol, not in StringSymbol itself. As a consequence, the new operator for StringSymbol cannot be invoked directly. Rather, new symbols should be created by calling Symbol.add(String).

See Also:

Symbol, IntSymbol, Serialized Form

Constructor Summary

StringSymbol()
A public, no-arg constructor, required by the Externalizable interface.

Method Summary

Integer	getInteger() Returns null, since this extension of Symbol only stores strings.
protected Object	getSymKey() Returns the key used by the internal symbol map of the class Symbol, which, for this type of symbol, is the String object returned by toString().
void	readExternal(ObjectInput in) Reads this object from an ObjectInput instance.
Object	readResolve() Deals with the issue of uniqueness when we are dealing with more than one VM by adding the read symbol to the symbol map, if it is not already there.
String	toString() Returns the print name of this Symbol.
void	writeExternal(ObjectOutput out) Writes this object to an ObjectOutput instance.

Methods inherited from class danbikel.lisp.Symbol

add, add, add, clean, deepCopy, get, get, get, isList, isSymbol

Methods inherited from class danbikel.lisp.Sexp

getCanonical, list, main, read, read, read, symbol

Methods inherited from class java.lang.Object

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

Constructor Detail

StringSymbol

public StringSymbol()

A public, no-arg constructor, required by the Externalizable interface.

StringSymbol objects should not be created via this constructor.

Method Detail

toString

public String toString()

Returns the print name of this Symbol.

Specified by:

toString in class Symbol

Returns:

the print name of this Symbol.

getInteger

public Integer getInteger()

Returns null, since this extension of Symbol only stores strings.

Specified by:

getInteger in class Symbol

Returns:

null

getSymKey

protected Object getSymKey()

Returns the key used by the internal symbol map of the class Symbol, which, for this type of symbol, is the String object returned by toString().

Specified by:

getSymKey in class Symbol

Returns:

the object returned by toString(). <

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Writes this object to an ObjectOutput instance.

Specified by:

writeExternal in interface Externalizable

Specified by:

writeExternal in class Sexp

Parameters:

out - the object stream to which to write an object of this class

Throws:

IOException - if the underlying write operation throws an IOException

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Reads this object from an ObjectInput instance.

Specified by:

readExternal in interface Externalizable

Specified by:

readExternal in class Sexp

Parameters:

in - the object stream from which to read objects of this class

Throws:

IOException - if the underlying read operation throws an IOException

ClassNotFoundException - if the underlying read operation throws an ClassNotFoundException

readResolve

public Object readResolve()
                   throws ObjectStreamException

Deals with the issue of uniqueness when we are dealing with more than one VM by adding the read symbol to the symbol map, if it is not already there.

Returns:

the canonical instance of the StringSymbol that was read from an ObjectInput instance

Throws:

ObjectStreamException - if there is a problem with the underlying read operation