Module Simula

Package simula.compiler.syntaxClass.expression

Class ObjectRelation

java.lang.Object

simula.compiler.syntaxClass.SyntaxClass

simula.compiler.syntaxClass.expression.Expression

simula.compiler.syntaxClass.expression.ObjectRelation

public final class ObjectRelation
extends Expression

Object relations

 Simula Standard: 3.3.4. Object relations
 
   object-relation
        =  simple-object-expression  IS  class-identifier
        |  simple-object-expression  IN  class-identifier
 

The operators IS and IN may be used to test the class membership of an object.

The relation "X IS C" has the value true if X refers to an object belonging to the class C, otherwise the value is false.

The relation "X IN C" has the value true if X refers to an object belonging to a class C or a class inner to C, otherwise the value is false.

The qualification of an object expression is defined by the following rules:

• The expression none is qualified by a fictitious class which is inner to all declared classes.
• A variable or function designator is qualified as stated in the declaration (or specification, see below) of the variable or array or procedure in question.
• An object generator, local object or qualified object is qualified by the class of the identifier following the symbol new, this or qua respectively.
• A conditional object expression is qualified by the innermost class which includes the qualifications of both alternatives. If there is no such class, the expression is illegal.
• Any formal parameter of object reference type is qualified according to its specification regardless of the qualification of the corresponding actual parameter.
• The qualification of a function designator whose procedure identifier is that of a virtual quantity depends on the access level (see 5.5.5). The qualification is that of the matching declaration, if any, occurring at the innermost prefix level equal or outer to the access level, or, if no such match exists, it is that of the virtual specification.

Link to GitHub: Source File.

Author:

SIMULA Standards Group, Øystein Myhre Andersen

Field Summary

Fields

Modifier and Type	Field	Description
(package private) ClassDeclaration	classDeclaration	The class declaration.
private final String	classIdentifier	The right hand class identifier.
private final Expression	lhs	The left hand side.
private final KeyWord	opr	The operation: IN, IS or QUA

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
ObjectRelation(Expression lhs, KeyWord opr, String classIdentifier)	Create a new ObjectRelation

Method Summary

Modifier and Type	Method	Description
void	doChecking()	Perform semantic checking.
boolean	maybeStatement()	Returns true if this expression may be used as a statement.
String	toJavaCode()	Generate Java code for this Syntax Class.
String	toString()

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

lhs

private final Expression lhs

The left hand side.

opr

private final KeyWord opr

The operation: IN, IS or QUA

classIdentifier

private final String classIdentifier

The right hand class identifier.

classDeclaration

ClassDeclaration classDeclaration

The class declaration.

Constructor Details

ObjectRelation

ObjectRelation(Expression lhs,
 KeyWord opr,
 String classIdentifier)

Create a new ObjectRelation

Parameters:

lhs - left hand side

opr - the operation: IN, IS or QUA

classIdentifier - the right hand class identifier

Method Details

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

toString

public String toString()

Overrides:

toString in class Expression