danbikel.lisp
Class Sexp

java.lang.Object
  danbikel.lisp.Sexp

All Implemented Interfaces:

Externalizable, Serializable

Direct Known Subclasses:

SexpList, Symbol

public abstract class Sexp
extends Object
implements Externalizable

This class provides the abstract base type for S-epxressions, which are either symbols or lists.

See Also:

Symbol, SexpList, Serialized Form

Method Summary

abstract Sexp	deepCopy() Returns a deep copy of this S-expression.
Sexp	getCanonical(Map map) Returns a canonical version of this S-expression.
abstract boolean	isList() Returns true if this is an instance of a SexpList, false otherwise.
abstract boolean	isSymbol() Returns true if this is an instance of a Symbol, false otherwise.
SexpList	list() Returns this object cast to a SexpList.
static void	main(String[] args) A (very simple) test driver for this class.
static Sexp	read(SexpTokenizer tok) Returns the S-expression contained in the stream held by tok.
static Sexp	read(SexpTokenizer tok, char open, char close)
static Sexp	read(String in) Returns the S-expression contained in the specified string.
abstract void	readExternal(ObjectInput oi) Reads this Sexp object from the specified object stream (to be implemented by all concrete subclasses).
Symbol	symbol() Returns this object cast to a Symbol.
abstract void	writeExternal(ObjectOutput oo) Writes this Sexp object from the specified object stream (to be implemented by all concrete subclasses).

Methods inherited from class java.lang.Object

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

Method Detail

symbol

public final Symbol symbol()

Returns this object cast to a Symbol.

Returns:

this object cast to a Symbol.

Throws:

ClassCastException - if this object is not type-compatible with Symbol

list

public final SexpList list()

Returns this object cast to a SexpList.

Returns:

this object case to a SexpList.

Throws:

ClassCastException - if this object is not type-compatible with SexpList

isList

public abstract boolean isList()

Returns true if this is an instance of a SexpList, false otherwise.

Returns:

true if this is an instance of a SexpList, false otherwise.

isSymbol

public abstract boolean isSymbol()

Returns true if this is an instance of a Symbol, false otherwise.

Returns:

true if this is an instance of a Symbol, false otherwise.

deepCopy

public abstract Sexp deepCopy()

Returns a deep copy of this S-expression.

Returns:

a deep copy of this S-expression.

getCanonical

public final Sexp getCanonical(Map map)

Returns a canonical version of this S-expression. If this S-expression is a symbol, this object is returned; otherwise, if it is a zero-element list, SexpList.emptyList is returned; otherwise, if it is a key in map, the map's value for this list is returned; otherwise, this list is added as a reflexive key-value pair in map, after its trimToSize method has been invoked. Note that this method has a superset of the functionality of SexpList.getCanonical(SexpList).

Parameters:

map - the reflexive map of SexpList objects with which to canonicalize this Sexp object

Returns:

a canonical version of this S-expression, using the specified map to perform canonicalization

See Also:

SexpList.getCanonical(SexpList), SexpList.trimToSize()

read

public static Sexp read(SexpTokenizer tok)
                 throws IOException

Returns the S-expression contained in the stream held by tok. If there are no tokens remaining in tok, this method returns null.

Parameters:

tok - the tokenizer from which to read an S-expression

Returns:

the next S-expression that can be read from the specified S-expression tokenizer

Throws:

IOException - if there is an unexpected end of stream, mismatched parentheses or an unexpected character

read

public static Sexp read(SexpTokenizer tok,
                        char open,
                        char close)
                 throws IOException

Throws:

IOException

read

public static Sexp read(String in)
                 throws IOException

Returns the S-expression contained in the specified string. If the string contains no tokens, this method returns null.

Parameters:

in - the string from which to read an S-expression

Returns:

the first S-expression contained in the specified string

Throws:

IOException - if there was an underlying problem reading from the specified string

readExternal

public abstract void readExternal(ObjectInput oi)
                           throws IOException,
                                  ClassNotFoundException

Reads this Sexp object from the specified object stream (to be implemented by all concrete subclasses).

Specified by:

readExternal in interface Externalizable

Parameters:

oi - the object input stream

Throws:

IOException - if the underlying stream has an exception

ClassNotFoundException - if the class of the object that is read cannot be found

writeExternal

public abstract void writeExternal(ObjectOutput oo)
                            throws IOException

Writes this Sexp object from the specified object stream (to be implemented by all concrete subclasses).

Specified by:

writeExternal in interface Externalizable

Parameters:

oo - the object output stream to which this object will be written

Throws:

IOException - if the underlying stream thrown an exception

main

public static void main(String[] args)

A (very simple) test driver for this class.

Parameters:

args - arguments (all currently ignored)