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 IS and IN.

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 Details

    • lhs

      private Expression lhs
      The left hand side.

    • opr

      private int opr
      The operation: IN or IS

    • classIdentifier

      private String classIdentifier
      The right hand class identifier.

    • classDeclaration

      ClassDeclaration classDeclaration
      The class declaration. Set by doChecking.

  • Constructor Details

    • ObjectRelation

      ObjectRelation(Expression lhs, int opr, String classIdentifier)
      Create a new ObjectRelation
      Parameters:
      lhs - left hand side
      opr - the operation: IN or IS
      classIdentifier - the right hand class identifier

    • ObjectRelation

      private ObjectRelation()
      Default constructor used by Attribute File I/O

  • 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

    • buildEvaluation

      public void buildEvaluation(Expression rightPart, CodeBuilder codeBuilder)
      Description copied from class: Expression
      ClassFile coding utility: Build Evaluation Code.
      Specified by:
      buildEvaluation in class Expression
      Parameters:
      rightPart - expression
      codeBuilder - the codeBuilder used.

    • toString

      public String toString()
      Overrides:
      toString in class Expression

    • writeObject

      public void writeObject(AttributeOutputStream oupt) throws IOException
      Description copied from class: SyntaxClass
      Write a SyntaxClass object to a AttributeOutputStream.
      Overrides:
      writeObject in class SyntaxClass
      Parameters:
      oupt - the AttributeOutputStream to write to.
      Throws:
      IOException - if something went wrong.

    • readObject

      public static ObjectRelation readObject(AttributeInputStream inpt) throws IOException
      Read and return a ObjectRelation object.
      Parameters:
      inpt - the AttributeInputStream to read from
      Returns:
      the ObjectRelation object read from the stream.
      Throws:
      IOException - if something went wrong.