sisc.data
Class Value

java.lang.Object
  sisc.util.Util
      sisc.data.Expression
          sisc.data.Value

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Immediate, ExpressionVisitee, Version

Direct Known Subclasses:

AnnotatedExpr, Box, Buffer, DelegatingSymEnv, EOFObject, ExpressionValue, HashtableBase, JavaObject, LexicalEnvironment, MemorySymEnv, NativeLibrary, Networking.SchemeServerSocket, Networking.SchemeSocket, Nothing, Pair, Procedure, Quantity, Record, SchemeBinaryInputPort, SchemeBinaryOutputPort, SchemeBoolean, SchemeCharacter, SchemeCharacterInputPort, SchemeCharacterOutputPort, SchemeString, SchemeThread, SchemeVector, SchemeVoid, Symbol, Syntax, Threads.CondVar, Threads.Mutex, Types.SchemeType, Values

public abstract class Value
extends Expression
implements Immediate

Value is the base class for anything treated as a first-class value within Scheme.

See Also:

Serialized Form

Field Summary

Fields inherited from class sisc.data.Expression

annotations, EMPTYSET

Fields inherited from class sisc.util.Util

BACKQUOTE, BEGIN, bundles, caseSensitive, EMPTYLIST, EMPTYVEC, EOF, ERRORK, EVAL, EXPSC, EXPTOP, FALSE, FCONT, FIVE, JEXCEPTION, LAMBDA, LOCATION, maxFloatPrecision, MESSAGE, minFloatPrecision, NAME, OTHER, PARENT, permitInterrupts, QUOTE, QUOTESYM, REPORT, SETBANG, SISC, SISC_SPECIFIC, SISCB, SOURCE_COLUMN, SOURCE_FILE, SOURCE_LINE, SYMENV, THIS, TOPLEVEL, TRUE, UNQUOTE, UNQUOTE_SPLICING, VOID, ZV

Fields inherited from interface sisc.util.Version

VERSION

Constructor Summary

Value()

Method Summary

void	apply(Interpreter r)
abstract void	display(ValueWriter w)
void	displayNamedOpaque(ValueWriter w, java.lang.String type) Helper function to generate an opaque type representation which may be named
boolean	equals(java.lang.Object v) Compares this Value to another.
boolean	eqv(java.lang.Object v) Compares this Value to another for equality according to the rules of Scheme's eqv?.
void	eval(Interpreter r) Called to evaluate this value.
Value	express() A debugging function, express returns a Scheme value that describes this expression.
Value	getValue(Interpreter r) Called to obtain the value of this Value.
java.lang.String	synopsis()
java.lang.String	synopsis(int limit) A synopsis is a limited number of characters of a human readable Value representation.
java.lang.String	toString()
boolean	valueEqual(Value v) Compares this value to another for semantic equality.
int	valueHashCode() a hashCode function consistent with valueEqual
void	write(ValueWriter w)
java.lang.Object	writeReplace()

Methods inherited from class sisc.data.Expression

deserialize, deserializeAnnotations, getAnnotation, getAnnotation, getAnnotationKeys, getAnnotations, getName, readExternal, readResolve, serialize, serializeAnnotations, setAnnotation, setAnnotation, setName, visit, visitAnnotations, writeExternal

Methods inherited from class sisc.util.Util

annotated, annotatedAppEval, append, argCheck, argsToSymbols, assq, bininport, bininstream, binoutport, binoutstream, box, character, charinport, charinreader, charoutport, charoutwriter, charsetFromString, chr, cont, currentClassLoader, env, error, error, error, error, error, error, error, expr, getDefaultCharacterSet, immutablePair, immutableVector, inport, javaExceptionToString, javaWrap, justify, length, liMessage, liMessage, liMessage, liMessage, liMessage, liMessage, liMessage, list, list, list, list, list, makeURL, mapcar, memq, nlib, num, outport, pair, pairToExpressions, pairToExpVect, pairToValues, proc, read, registerBundle, reverse, reverseInPlace, simpleErrorToString, sourceAnnotations, str, string, sym, symbol, symval, truePair, truth, truth, typeError, typeError, updateName, url, url, url, valArrayToList, valArrayToList, valArrayToVec, vec, warn, warn, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

Value

public Value()

Method Detail

display

public abstract void display(ValueWriter w)
                      throws java.io.IOException

Throws:

java.io.IOException

apply

public void apply(Interpreter r)
           throws ContinuationException

Throws:

ContinuationException

synopsis

public java.lang.String synopsis()

synopsis

public java.lang.String synopsis(int limit)

A synopsis is a limited number of characters of a human readable Value representation. They are used in errors or informational messages where the entire value's representation is not necessary.

Parameters:

limit - The number of characters to display

write

public void write(ValueWriter w)
           throws java.io.IOException

Throws:

java.io.IOException

equals

public boolean equals(java.lang.Object v)

Compares this Value to another. By default equal to eqv.

Overrides:

equals in class java.lang.Object

Parameters:

v - the other Value

eqv

public boolean eqv(java.lang.Object v)

Compares this Value to another for equality according to the rules of Scheme's eqv?. In SISC, this differs from eq? in that eq? is strict pointer equality.

Parameters:

v - the other Value

valueEqual

public boolean valueEqual(Value v)

Compares this value to another for semantic equality. Used to implement Scheme's 'equal?'. Subclasses must test for pointer equality as well as semantic equality, so that infinite loops on recursive structures are less likely.

Parameters:

v - the other Value

valueHashCode

public int valueHashCode()

a hashCode function consistent with valueEqual

Returns:

hash code

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

eval

public void eval(Interpreter r)
          throws ContinuationException

Called to evaluate this value. As Values ordinarily evaluate to themselves, this method simply sets acc to this.

Specified by:

eval in class Expression

Parameters:

r -

Throws:

ContinuationException

getValue

public Value getValue(Interpreter r)
               throws ContinuationException

Called to obtain the value of this Value. Simply this.

Specified by:

getValue in interface Immediate

Overrides:

getValue in class Expression

Parameters:

r -

Returns:

the immediate value of this expression, or null if the value cannot be obtained immediately.

Throws:

ContinuationException

express

public Value express()

Description copied from class: Expression

A debugging function, express returns a Scheme value that describes this expression. See examples in sisc.exprs.*

Specified by:

express in class Expression

displayNamedOpaque

public void displayNamedOpaque(ValueWriter w,
                               java.lang.String type)
                        throws java.io.IOException

Helper function to generate an opaque type representation which may be named

Throws:

java.io.IOException

writeReplace

public java.lang.Object writeReplace()
                              throws java.io.ObjectStreamException

Throws:

java.io.ObjectStreamException