Package gnu.expr

Class Keyword

java.lang.Object

gnu.mapping.Symbol

gnu.expr.Keyword

All Implemented Interfaces:

EnvironmentKey, Externalizable, Serializable, Comparable

public class Keyword
extends Symbol
implements Externalizable

Implementation of Lisp keywords. Keywords are symbolic identifiers that evaluate to themselves, as opposed to symbols which generally name other values.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static Namespace	keywordNamespace

Fields inherited from class gnu.mapping.Symbol

FUNCTION, name, PLIST

Constructor Summary

Constructors

Constructor	Description
Keyword()
Keyword(Namespace namespace, String name)	Used for constructing literals (int gnu.expr.LitTable).

Method Summary

Modifier and Type	Method	Description
Symbol	asSymbol()	Get the corresponding non-keyword symbol.
static boolean	isKeyword(Object obj)	Test whether an object is a keyword.
static Keyword	make(String name)	Create or find a Keyword with a given name (without ':').
void	readExternal(ObjectInput in)
Object	readResolve()
static Object	searchForKeyword(Object[] vals, int offset, Object keyword)	Search vals[0:offset-1] for a keyword.
static Object	searchForKeyword(Object[] vals, int offset, Object keyword, Object dfault)	Search vals[0:offset-1] for a keyword.
String	toString()
void	writeExternal(ObjectOutput out)

Methods inherited from class gnu.mapping.Symbol

compareTo, equals, equals, getKeyProperty, getKeySymbol, getLocalName, getLocalPart, getName, getNamespace, getNamespaceURI, getPrefix, hasEmptyNamespace, hashCode, hasUnknownNamespace, make, make, makeUninterned, makeUninterned, makeWithUnknownNamespace, matches, matches, parse, setNamespace, toString, valueOf, valueOf, valueOf

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

keywordNamespace

public static final Namespace keywordNamespace

Constructor Detail

Keyword

public Keyword()

Keyword

public Keyword(Namespace namespace,
               String name)

Used for constructing literals (int gnu.expr.LitTable).

Method Detail

asSymbol

public Symbol asSymbol()

Get the corresponding non-keyword symbol. Informally, the symbol corresponding to dropping the ':'.

make

public static Keyword make(String name)

Create or find a Keyword with a given name (without ':').

Parameters:

name - the print-name of the desired Keyword

Returns:

a Keyword with the given name, newly created iff none such exist

isKeyword

public static boolean isKeyword(Object obj)

Test whether an object is a keyword.

Parameters:

obj - the object to test.

Returns:

true if the object is a keyword, false otherwise.

toString

public final String toString()

Overrides:

toString in class Symbol

searchForKeyword

public static Object searchForKeyword(Object[] vals,
                                      int offset,
                                      Object keyword)

Search vals[0:offset-1] for a keyword. Each key at vals[i] is followed by a value at keys[i+1]. (This is used to search for a keyword parameter in an argument list.)

Parameters:

vals - the list to search in

offset - the index in vals to start the search at

keyword - the keyword to search for

Returns:

vals[i+1] such that vals[i]==keyword (and (i-offset) is even and non-negative); if there is no such i, return Special.dfault.

searchForKeyword

public static Object searchForKeyword(Object[] vals,
                                      int offset,
                                      Object keyword,
                                      Object dfault)

Search vals[0:offset-1] for a keyword. Each key at vals[i] is followed by a value at keys[i+1]. (This is used to search for a keyword parameter in an argument list.)

Parameters:

vals - the list to search in

offset - the index in vals to start the search at

keyword - the keyword to search for

dfault - the value to return if there is no match

Returns:

vals[i+1] such that vals[i]==keyword (and (i-offset) is even and non-negative); if there is no such i, return dfault.

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Overrides:

writeExternal in class Symbol

Throws:

IOException

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Overrides:

readExternal in class Symbol

Throws:

IOException

ClassNotFoundException

readResolve

public Object readResolve()
                   throws ObjectStreamException

Overrides:

readResolve in class Symbol

Throws:

ObjectStreamException