(*
$Id$
ISO TC184/SC4/WG12 N2887 - ISO/IS 10303-41 Fundamentals of product description and support - EXPRESS
*) 


SCHEMA document_schema;

REFERENCE FROM product_definition_schema   -- ISO 10303-41
  (product,
   product_definition,
   product_definition_formation); 

REFERENCE FROM support_resource_schema   -- ISO 10303-41
  (bag_to_set,
   identifier,
   label,
   text); 


TYPE product_or_formation_or_definition = SELECT
   (product, 
    product_definition_formation, 
    product_definition);
END_TYPE; 

ENTITY document;
  id : identifier;
  name : label;
  description : OPTIONAL text;
  kind : document_type;
INVERSE
  representation_types : SET[0:?] OF document_representation_type FOR represented_document;
END_ENTITY;

ENTITY document_product_association;
  name : label;
  description : OPTIONAL text;
  relating_document : document;
  related_product : product_or_formation_or_definition;
END_ENTITY;

ENTITY document_relationship;
  name : label;
  description : OPTIONAL text;
  relating_document : document;
  related_document : document;
END_ENTITY;

ENTITY document_representation_type;
  name : label;
  represented_document : document;
END_ENTITY;

ENTITY document_type;
  product_data_type : label;
END_ENTITY;

ENTITY document_usage_constraint;
  source : document;
  subject_element : label;
  subject_element_value : text;
END_ENTITY;

ENTITY document_with_class
  SUBTYPE OF (document);
  class : identifier;
END_ENTITY;

FUNCTION acyclic_document_relationship
 (relation : document_relationship; relatives : SET[1:?] OF document; specific_relation : STRING) : BOOLEAN; 
 LOCAL
      x : SET OF document_relationship;
    END_LOCAL;

    IF relation.relating_document IN relatives THEN
      RETURN (FALSE);
    END_IF;
    x := QUERY(doc <* bag_to_set(USEDIN(relation.relating_document, 'DOCUMENT_SCHEMA.' + 'DOCUMENT_RELATIONSHIP.' + 'RELATED_DOCUMENT')) | specific_relation IN TYPEOF(doc));
    REPEAT i := 1 TO HIINDEX(x);
      IF NOT acyclic_document_relationship(x[i], relatives + relation.relating_document, specific_relation) THEN
        RETURN (FALSE);
      END_IF;
    END_REPEAT;
    RETURN (TRUE);
END_FUNCTION; 

END_SCHEMA;  -- document_schema
