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 the 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 the lowest element in set.

Function TSetTypeDefinition.GetSetSizeAndLowestElementDataOffset (Var DataOffset: Byte): Byte;
begin
  GetSetSizeAndLowestElementDataOffset := Size;
  DataOffset := POrdinalTypeDefinition (PointerFromOffsets (BaseSetTypeOffset))^.LowerLimit shr 3;
end;