Type Definition Functions

Array and set definitions use few functons for type checking. This function checks if type is zero-based character array:
  • Base type must be Array
  • Element type must be System.Char
  • Size must be non zero
  • Index base type must be btInteger
  • Index lower limit must be zero
Function TArrayTypeDefinition.IsZeroBasedCharacterArray: Boolean;
begin
  IsZeroBasedCharacterArray := False;
  If BaseType <> btArray then Exit;
  If ElementTypeOffset.TypeOffset <> Char_TypeOffset then Exit;
  If PUnitIdentifierData (Ptr (Seg (Self), ElementTypeOffset.UnitIdentifierData))^.UnitSegment <>
       SystemUnitSegment then Exit;
  If Size < 1 then Exit;
  With POrdinalTypeDefinition (PointerFromOffsets (IndexTypeOffset))^ do
    begin
      If BaseType <> btInteger then Exit;
      If LowerLimit <> 0 then Exit;
    end;
  IsZeroBasedCharacterArray := True
end;
This function checks if type is character array compatible with string:
  • Base type must be Array
  • Element base type must be Char
  • Size must be between 1 and 255
Variable Len returns actual array size.
Function TArrayTypeDefinition.IsCharacterArrayCompatibleWithString (Var Len: Byte): Boolean;
begin
  IsCharacterArrayCompatibleWithString := False;
  If BaseType <> btArray then Exit;
  If PTypeDefinition (PointerFromOffsets (ElementTypeOffset))^.BaseType <> btChar then Exit;
  If Size < 1 then Exit;
  If Size > 255 then Exit;
  Len := Size;
  IsCharacterArrayCompatibleWithString := True;
end;
This function returns set size and offset of lowest element in set.
Function TSetTypeDefinition.GetSetSizeAndLowestElementDataOffset (Var DataOffset: Byte): Byte;
begin
  GetSetSizeAndLowestElementDataOffset := Size;
  DataOffset := POrdinalTypeDefinition (PointerFromOffsets (BaseSetTypeOffset))^.LowerLimit shr 3;
end;
 
 
 
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