sisc.data
Class Expression

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

All Implemented Interfaces:

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

Direct Known Subclasses:

AppEval, AppExp, ApplyValuesContEval, DefineEval, EvalExp, FillRibExp, FixedAppExp_0, FreeReferenceExp, FreeSetEval, IfEval, Interpreter.ThrowSchemeException, LambdaExp, LetrecEval, LexicalReferenceExp, LocalReferenceExp, SetboxEval, UnboxExp, Value

public abstract class Expression
extends Util
implements java.io.Externalizable, ExpressionVisitee

The base class for any and all expressions. An expression is anything in Scheme that can evaluate to a value. In SISC, an expression can be annotated. An annotation is any key/value pair attached to an expression for the duration of its lifetime. Annotations are used to implement procedure properties and source-tracked debugging.

See Also:

Serialized Form

Field Summary

java.util.Map	annotations
protected static java.util.Set	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

Expression()

Method Summary

void	deserialize(Deserializer s) All Expressions must implement a default (no-argument) constructor.
void	deserializeAnnotations(Deserializer s)
abstract void	eval(Interpreter r) All expressions can be evaluated to some Scheme value.
abstract Value	express() A debugging function, express returns a Scheme value that describes this expression.
Value	getAnnotation(Symbol key)
Value	getAnnotation(Symbol key, Value def)
java.util.Set	getAnnotationKeys()
Pair	getAnnotations()
Symbol	getName()
Value	getValue(Interpreter r) If an expression implements the Immediate interface, it must override getValue, which returns as a Value, the immediate value of this expression.
void	readExternal(java.io.ObjectInput in)
java.lang.Object	readResolve()
void	serialize(Serializer s) All Expressions must implement a default (no-argument) constructor.
void	serializeAnnotations(Serializer s)
Value	setAnnotation(Symbol key, Value val)
Value	setAnnotation(Symbol key, Value val, Value def)
void	setName(Symbol s) The following helpers set the 'name annotation, which is used for naming procedures, environments, etc.
boolean	visit(ExpressionVisitor v)
boolean	visitAnnotations(ExpressionVisitor v)
void	writeExternal(java.io.ObjectOutput out)

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

Field Detail

EMPTYSET

protected static java.util.Set EMPTYSET

annotations

public java.util.Map annotations

Constructor Detail

Expression

public Expression()

Method Detail

getAnnotation

public Value getAnnotation(Symbol key,
                           Value def)

getAnnotation

public Value getAnnotation(Symbol key)

setAnnotation

public Value setAnnotation(Symbol key,
                           Value val,
                           Value def)

setAnnotation

public Value setAnnotation(Symbol key,
                           Value val)

getAnnotationKeys

public java.util.Set getAnnotationKeys()

getAnnotations

public Pair getAnnotations()

serializeAnnotations

public void serializeAnnotations(Serializer s)
                          throws java.io.IOException

Throws:

java.io.IOException

deserializeAnnotations

public void deserializeAnnotations(Deserializer s)
                            throws java.io.IOException

Throws:

java.io.IOException

visitAnnotations

public boolean visitAnnotations(ExpressionVisitor v)

setName

public void setName(Symbol s)

The following helpers set the 'name annotation, which is used for naming procedures, environments, etc.

getName

public Symbol getName()

eval

public abstract void eval(Interpreter r)
                   throws ContinuationException

All expressions can be evaluated to some Scheme value. This function implements the exact manner in which an expression is evaluated. An expression, when evaluated, performs some action that results in its value being placed in the acc register of the given Interpreter. An expression that immediately evaluates to a value (i.e. does not require that an additional expression be evaluated to obtain its value) must clear the nxp register by setting it to null. Otherwise, nxp should be set to the expression that is to be evaluated next before this method returns.

Parameters:

r - the Interpreter

Throws:

ContinuationException

getValue

public Value getValue(Interpreter r)
               throws ContinuationException,
                      OptimismUnwarrantedException

If an expression implements the Immediate interface, it must override getValue, which returns as a Value, the immediate value of this expression.

Parameters:

r - the Interpreter

Returns:

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

Throws:

ContinuationException

OptimismUnwarrantedException

express

public abstract Value express()

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

serialize

public void serialize(Serializer s)
               throws java.io.IOException

All Expressions must implement a default (no-argument) constructor. Those that wish to be serialized to a heap must implement both this and the deserialize method. The Expression may use any method of the Serializer, which implements java.io.DataOutput to write its state.

Parameters:

s - the Serializer

Throws:

java.io.IOException

deserialize

public void deserialize(Deserializer s)
                 throws java.io.IOException

All Expressions must implement a default (no-argument) constructor. Those that wish to b serialized to a heap must implement both this and the serialize method. The Expression may use any method of the DataInput stream and the Deserializer serialization context to read its state.

Parameters:

s - the Deserializer

Throws:

java.io.IOException

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readResolve

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

Throws:

java.io.ObjectStreamException

visit

public boolean visit(ExpressionVisitor v)

Specified by:

visit in interface ExpressionVisitee