checker.java

The triangle language processor will be consist of a compiler, an interpreter, and a disassembler

  public Object visitProcDeclaration(ProcDeclaration ast, Object o) {
    idTable.enter (ast.I.spelling, ast); // permits recursion
    if (ast.duplicated)
      reporter.reportError ("identifier \"%\" already declared",
                            ast.I.spelling, ast.position);
    idTable.openScope();
    ast.FPS.visit(this, null);
    ast.C.visit(this, null);
    idTable.closeScope();
    return null;
  }

  public Object visitSequentialDeclaration(SequentialDeclaration ast, Object o) {
    ast.D1.visit(this, null);
    ast.D2.visit(this, null);
    return null;
  }

  public Object visitTypeDeclaration(TypeDeclaration ast, Object o) {
    ast.T = (TypeDenoter) ast.T.visit(this, null);
    idTable.enter (ast.I.spelling, ast);
    if (ast.duplicated)
      reporter.reportError ("identifier \"%\" already declared",
                            ast.I.spelling, ast.position);
    return null;
  }

  public Object visitUnaryOperatorDeclaration(UnaryOperatorDeclaration ast, Object o) {
    return null;
  }

  public Object visitVarDeclaration(VarDeclaration ast, Object o) {
    ast.T = (TypeDenoter) ast.T.visit(this, null);
    idTable.enter (ast.I.spelling, ast);
    if (ast.duplicated)
      reporter.reportError ("identifier \"%\" already declared",
                            ast.I.spelling, ast.position);

    return null;
  }

  // Array Aggregates

  // Returns the TypeDenoter for the Array Aggregate. Does not use the
  // given object.

  public Object visitMultipleArrayAggregate(MultipleArrayAggregate ast, Object o) {
    TypeDenoter eType = (TypeDenoter) ast.E.visit(this, null);
    TypeDenoter elemType = (TypeDenoter) ast.AA.visit(this, null);
    ast.elemCount = ast.AA.elemCount + 1;
    if (! eType.equals(elemType))
      reporter.reportError ("incompatible array-aggregate element", "", ast.E.position);
    return elemType;
  }

  public Object visitSingleArrayAggregate(SingleArrayAggregate ast, Object o) {
    TypeDenoter elemType = (TypeDenoter) ast.E.visit(this, null);
    ast.elemCount = 1;
    return elemType;
  }

  // Record Aggregates

  // Returns the TypeDenoter for the Record Aggregate. Does not use the
  // given object.

  public Object visitMultipleRecordAggregate(MultipleRecordAggregate ast, Object o) {
    TypeDenoter eType = (TypeDenoter) ast.E.visit(this, null);
    FieldTypeDenoter rType = (FieldTypeDenoter) ast.RA.visit(this, null);
    TypeDenoter fType = checkFieldIdentifier(rType, ast.I);
    if (fType != StdEnvironment.errorType)
      reporter.reportError ("duplicate field \"%\" in record",
                            ast.I.spelling, ast.I.position);
    ast.type = new MultipleFieldTypeDenoter(ast.I, eType, rType, ast.position);
    return ast.type;
  }

  public Object visitSingleRecordAggregate(SingleRecordAggregate ast, Object o) {
    TypeDenoter eType = (TypeDenoter) ast.E.visit(this, null);
    ast.type = new SingleFieldTypeDenoter(ast.I, eType, ast.position);
    return ast.type;
  }

  // Formal Parameters

  // Always returns null. Does not use the given object.

  public Object visitConstFormalParameter(ConstFormalParameter ast, Object o) {
    ast.T = (TypeDenoter) ast.T.visit(this, null);
    idTable.enter(ast.I.spelling, ast);
    if (ast.duplicated)
      reporter.reportError ("duplicated formal parameter \"%\"",
                            ast.I.spelling, ast.position);
    return null;
  }

  public Object visitFuncFormalParameter(FuncFormalParameter ast, Object o) {
    idTable.openScope();
    ast.FPS.visit(this, null);
    idTable.closeScope();
    ast.T = (TypeDenoter) ast.T.visit(this, null);
    idTable.enter (ast.I.spelling, ast);
    if (ast.duplicated)
      reporter.reportError ("duplicated formal parameter \"%\"",
                            ast.I.spelling, ast.position);
    return null;
  }

  public Object visitProcFormalParameter(ProcFormalParameter ast, Object o) {
    idTable.openScope();
    ast.FPS.visit(this, null);
    idTable.closeScope();
    idTable.enter (ast.I.spelling, ast);
    if (ast.duplicated)
      reporter.reportError ("duplicated formal parameter \"%\"",
                            ast.I.spelling, ast.position);
    return null;
  }

  public Object visitVarFormalParameter(VarFormalParameter ast, Object o) {
    ast.T = (TypeDenoter) ast.T.visit(this, null);
    idTable.enter (ast.I.spelling, ast);
    if (ast.duplicated)
      reporter.reportError ("duplicated formal parameter \"%\"",
                            ast.I.spelling, ast.position);
    return null;
  }

  public Object visitEmptyFormalParameterSequence(EmptyFormalParameterSequence ast, Object o) {
    return null;
  }

  public Object visitMultipleFormalParameterSequence(MultipleFormalParameterSequence ast, Object o) {
    ast.FP.visit(this, null);
    ast.FPS.visit(this, null);
    return null;
  }

  public Object visitSingleFormalParameterSequence(SingleFormalParameterSequence ast, Object o) {
    ast.FP.visit(this, null);
    return null;
  }

  // Actual Parameters

  // Always returns null. Uses the given FormalParameter.

  public Object visitConstActualParameter(ConstActualParameter ast, Object o) {
    FormalParameter fp = (FormalParameter) o;
    TypeDenoter eType = (TypeDenoter) ast.E.visit(this, null);

    if (! (fp instanceof ConstFormalParameter))
      reporter.reportError ("const actual parameter not expected here", "",
                            ast.position);
    else if (! eType.equals(((ConstFormalParameter) fp).T))
      reporter.reportError ("wrong type for const actual parameter", "",
                            ast.E.position);
    return null;
  }

  public Object visitFuncActualParameter(FuncActualParameter ast, Object o) {
    FormalParameter fp = (FormalParameter) o;

    Declaration binding = (Declaration) ast.I.visit(this, null);
    if (binding == null)
      reportUndeclared (ast.I);
    else if (! (binding instanceof FuncDeclaration ||
                binding instanceof FuncFormalParameter))
      reporter.reportError ("\"%\" is not a function identifier",
                            ast.I.spelling, ast.I.position);
    else if (! (fp instanceof FuncFormalParameter))
      reporter.reportError ("func actual parameter not expected here", "",
                            ast.position);
    else {
      FormalParameterSequence FPS = null;
      TypeDenoter T = null;
      if (binding instanceof FuncDeclaration) {
        FPS = ((FuncDeclaration) binding).FPS;
        T = ((FuncDeclaration) binding).T;
      } else {
        FPS = ((FuncFormalParameter) binding).FPS;
        T = ((FuncFormalParameter) binding).T;
      }
      if (! FPS.equals(((FuncFormalParameter) fp).FPS))
        reporter.reportError ("wrong signature for function \"%\"",
                              ast.I.spelling, ast.I.position);
      else if (! T.equals(((FuncFormalParameter) fp).T))
        reporter.reportError ("wrong type for function \"%\"",
                              ast.I.spelling, ast.I.position);
    }
    return null;
  }

  public Object visitProcActualParameter(ProcActualParameter ast, Object o) {
    FormalParameter fp = (FormalParameter) o;

    Declaration binding = (Declaration) ast.I.visit(this, null);
    if (binding == null)
      reportUndeclared (ast.I);
    else if (! (binding instanceof ProcDeclaration ||
                binding instanceof ProcFormalParameter))
      reporter.reportError ("\"%\" is not a procedure identifier",
                            ast.I.spelling, ast.I.position);
    else if (! (fp instanceof ProcFormalParameter))
      reporter.reportError ("proc actual parameter not expected here", "",
                            ast.position);
    else {
      FormalParameterSequence FPS = null;
      if (binding instanceof ProcDeclaration)
        FPS = ((ProcDeclaration) binding).FPS;
      else
        FPS = ((ProcFormalParameter) binding).FPS;
      if (! FPS.equals(((ProcFormalParameter) fp).FPS))
        reporter.reportError ("wrong signature for procedure \"%\"",
                              ast.I.spelling, ast.I.position);
    }
    return null;
  }

  public Object visitVarActualParameter(VarActualParameter ast, Object o) {
    FormalParameter fp = (FormalParameter) o;

    TypeDenoter vType = (TypeDenoter) ast.V.visit(this, null);
    if (! ast.V.variable)
      reporter.reportError ("actual parameter is not a variable", "",
                            ast.V.position);
    else if (! (fp instanceof VarFormalParameter))
      reporter.reportError ("var actual parameter not expected here", "",
                            ast.V.position);
    else if (! vType.equals(((VarFormalParameter) fp).T))
      reporter.reportError ("wrong type for var actual parameter", "",
                            ast.V.position);
    return null;
  }

  public Object visitEmptyActualParameterSequence(EmptyActualParameterSequence ast, Object o) {
    FormalParameterSequence fps = (FormalParameterSequence) o;
    if (! (fps instanceof EmptyFormalParameterSequence))
      reporter.reportError ("too few actual parameters", "", ast.position);
    return null;
  }

  public Object visitMultipleActualParameterSequence(MultipleActualParameterSequence ast, Object o) {
    FormalParameterSequence fps = (FormalParameterSequence) o;
    if (! (fps instanceof MultipleFormalParameterSequence))
      reporter.reportError ("too many actual parameters", "", ast.position);
    else {
      ast.AP.visit(this, ((MultipleFormalParameterSequence) fps).FP);
      ast.APS.visit(this, ((MultipleFormalParameterSequence) fps).FPS);
    }
    return null;
  }

  public Object visitSingleActualParameterSequence(SingleActualParameterSequence ast, Object o) {
    FormalParameterSequence fps = (FormalParameterSequence) o;
    if (! (fps instanceof SingleFormalParameterSequence))
      reporter.reportError ("incorrect number of actual parameters", "", ast.position);
    else {
      ast.AP.visit(this, ((SingleFormalParameterSequence) fps).FP);
    }
    return null;
  }

  // Type Denoters

  // Returns the expanded version of the TypeDenoter. Does not
  // use the given object.

  public Object visitAnyTypeDenoter(AnyTypeDenoter ast, Object o) {
    return StdEnvironment.anyType;
  }

  public Object visitArrayTypeDenoter(ArrayTypeDenoter ast, Object o) {
    ast.T = (TypeDenoter) ast.T.visit(this, null);
    if ((Integer.valueOf(ast.IL.spelling).intValue()) == 0)
      reporter.reportError ("arrays must not be empty", "", ast.IL.position);
    return ast;
  }

  public Object visitBoolTypeDenoter(BoolTypeDenoter ast, Object o) {
    return StdEnvironment.booleanType;
  }

  public Object visitCharTypeDenoter(CharTypeDenoter ast, Object o) {
    return StdEnvironment.charType;
  }

  public Object visitErrorTypeDenoter(ErrorTypeDenoter ast, Object o) {
    return StdEnvironment.errorType;
  }

  public Object visitSimpleTypeDenoter(SimpleTypeDenoter ast, Object o) {
    Declaration binding = (Declaration) ast.I.visit(this, null);
    if (binding == null) {
      reportUndeclared (ast.I);
      return StdEnvironment.errorType;
    } else if (! (binding instanceof TypeDeclaration)) {
      reporter.reportError ("\"%\" is not a type identifier",
                            ast.I.spelling, ast.I.position);
      return StdEnvironment.errorType;
    }
    return ((TypeDeclaration) binding).T;
  }

  public Object visitIntTypeDenoter(IntTypeDenoter ast, Object o) {
    return StdEnvironment.integerType;
  }

  public Object visitRecordTypeDenoter(RecordTypeDenoter ast, Object o) {
    ast.FT = (FieldTypeDenoter) ast.FT.visit(this, null);
    return ast;
  }

  public Object visitMultipleFieldTypeDenoter(MultipleFieldTypeDenoter ast, Object o) {