Module Simula

Package simula.compiler.syntaxClass.expression

Class Constant

java.lang.Object

simula.compiler.syntaxClass.SyntaxClass

simula.compiler.syntaxClass.expression.Expression

simula.compiler.syntaxClass.expression.Constant

All Implemented Interfaces:

Externalizable, Serializable

public final class Constant
extends Expression
implements Externalizable

Constant.

All constants are treated by the Lexicographical Scanner.

 
 Syntax:
 
   Constant = unsigned-number | string | character-constant | NONE | NOTEXT
   
 

Link to GitHub: Source File.

Author:

Øystein Myhre Andersen

See Also:

• SimulaScanner
• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
Object	value	The constant's value

Fields inherited from class simula.compiler.syntaxClass.expression.Expression

backLink, type

Fields inherited from class simula.compiler.syntaxClass.SyntaxClass

lineNumber

Constructor Summary

Constructors

Constructor	Description
Constant()	Default constructor used by Externalization.
Constant(Type type, Object value)	Create a new Constant.

Method Summary

Modifier and Type	Method	Description
private void	appendHex(StringBuilder sb, char c)	Encoding Utility: Edit hex(c) and append it to the given StringBuilder.
(package private) static Constant	createRealType(Object value)	Create a real type Constant.
void	doChecking()	Perform semantic checking.
private String	encode(String s)	Encode a string with escape sequences.
(package private) static Constant	evaluate(Number lhn, KeyWord opr, Number rhn)	Simplify this Constant.
(package private) static Constant	evaluate(KeyWord opr, Number rhn)	Simplify this Constant.
private static Type	getType(Number n)	Returns the type of this number.
boolean	maybeStatement()	Returns true if this expression may be used as a statement.
void	readExternal(ObjectInput inpt)
String	toJavaCode()	Generate Java code for this Syntax Class.
String	toString()
void	writeExternal(ObjectOutput oupt)

Methods inherited from class simula.compiler.syntaxClass.expression.Expression

acceptExpression, checkCompatibility, evaluate, expectExpression, get, getInt, getNumber, getQualification, getWriteableVariable, printTree, put

Methods inherited from class simula.compiler.syntaxClass.SyntaxClass

ASSERT_SEMANTICS_CHECKED, doDeclarationCoding, doJavaCoding, edIndent, edTreeIndent, IS_SEMANTICS_CHECKED, print, SET_SEMANTICS_CHECKED

Methods inherited from class java.lang.Object

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

Field Details

value

public Object value

The constant's value

Constructor Details

Constant

public Constant(Type type,
 Object value)

Create a new Constant.

Parameters:

type - the constant's type

value - the constant's value

Constant

public Constant()

Default constructor used by Externalization.

Method Details

createRealType

static Constant createRealType(Object value)

Create a real type Constant.

Parameters:

value - a real type value

Returns:

the resulting Constant

getType

private static Type getType(Number n)

Returns the type of this number.

Parameters:

n - the number

Returns:

the type of this number.

evaluate

static Constant evaluate(KeyWord opr,
 Number rhn)

Simplify this Constant.

Parameters:

opr - an unary operation

rhn - a right hand Number

Returns:

the resulting Constant

evaluate

static Constant evaluate(Number lhn,
 KeyWord opr,
 Number rhn)

Simplify this Constant.

Parameters:

lhn - a left hand Number

opr - an binary operation

rhn - a right hand Number

Returns:

the resulting Constant

doChecking

public void doChecking()

Description copied from class: SyntaxClass

Perform semantic checking.

This must be redefined in every subclass.

Overrides:

doChecking in class SyntaxClass

maybeStatement

public boolean maybeStatement()

Description copied from class: Expression

Returns true if this expression may be used as a statement.

Specified by:

maybeStatement in class Expression

Returns:

true if this expression may be used as a statement

toJavaCode

public String toJavaCode()

Description copied from class: SyntaxClass

Generate Java code for this Syntax Class.

Overrides:

toJavaCode in class SyntaxClass

Returns:

Java code

encode

private String encode(String s)

Encode a string with escape sequences.

Parameters:

s - the string

Returns:

a string with escape sequences.

appendHex

private void appendHex(StringBuilder sb,
 char c)

Encoding Utility: Edit hex(c) and append it to the given StringBuilder.

Parameters:

sb - the StringBuilder

c - the input character

toString

public String toString()

Overrides:

toString in class Expression

writeExternal

public void writeExternal(ObjectOutput oupt)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException

readExternal

public void readExternal(ObjectInput inpt)
                  throws IOException,
ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException

ClassNotFoundException