Element Extension

Element Extension
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The general mapping for complexContent with an extension element group is as follows:

XSD type:

   <xsd:complexType name=”TypeName”>
      <xsd:complexContent>
         <xsd:extension base="BaseType">
            <xsd:group>
               <xsd:element name="elem1" type="Type1"/>
               <xsd:element name="elem2" type="Type2"/>
               ...
               <xsd:element name="elemN" type="TypeN"/>
            </xsd:group>
         </xsd:extension>
      </xsd:complexContent>
   </xsd:complexType>

Generated C code:

   typedef struct TypeName_2 {
      group type definition..
   } TypeName_2;

   typedef struct TypeName {
      BaseType base;
      TypeName_2 ext;
   } TypeName;

   typedef struct BaseType_derivations {
      OSUINT16 t;
      union {
         /* t = 1 */
         struct BaseType *baseType;
         /* t = 2 */
         struct TypeName *typeName;
      } u;
   } BaseType_derivations;

Generated C++ code (extended model):

   class TypeName_2 : public OSXSDComplexType {
      group type definition..
   } ;

   class TypeName : public BaseType {
   public:
      TypeName_2 _ext;
   } ;

Generated C++ code (interface model):

   class TypeName : public BaseType_derivations {
   public:
      group type definition..
   } ;

   class BaseType_derivations : public OSXSDComplexType {
   public:
      BaseType_derivations () {}
   ...
   } ;

Notes:

group in the extension group definition above can be any content model group type (sequence, all, choice, or group).
In the case of C and C++ extended, the extension group is pulled out to form the temporary type (TypeName_2). The internals of this type depend on the content group type.
In the case of C++ interface, all content items (attributes and elements) are contained in the derived class.

Example: Extension Elements

The following complexContent type contains a choice of two additional elements that were not defined in the base type (ProductType):

   <xsd:complexType name="ShirtType">
      <xsd:complexContent>
         <xsd:extension base="ProductType">
            <xsd:choice>
               <xsd:element name="size" type="SizeType"/>
               <xsd:element name="color" type="ColorType"/>
            </xsd:choice>
         </xsd:extension>
      </xsd:complexContent>
   </xsd:complexType>

The following are the C typedefs that are generated for this definition:

    #define T_ShirtType_2_size 1
    #define T_ShirtType_2_color 2

    typedef struct EXTERN ShirtType_2 {
       OSUINT16 t;
       union {
          /* t = 1 */
          SizeType size;
          /* t = 2 */
          ColorType color;
       } u;
    } ShirtType_2;

    typedef struct EXTERN ShirtType {
       ProductType _base;
       ShirtType_2 _ext;
    } ShirtType;


    #define T_ProductType_derivations_productType1
    #define T_ProductType_derivations_shirtType2

    struct EXTERN ProductType;
    struct EXTERN ShirtType;

    typedef struct EXTERN ProductType_derivations {
       OSUINT16 t;
       union {
          /* t = 1 */
          struct ProductType *productType;
          /* t = 2 */
          struct ShirtType *shirtType;
       } u;
    } ProductType_derivations;

The case of C++ with the extended model is similar:

class ShirtType : public ProductType {
public:
   // tag constants
   enum {
      T_size = 1,
      T_color = 2
   } ;
   /**
    * ShirtType member variables
    */
   OSUINT16 t;
   union {
      /* t = 1 */
      SizeType *size;
      /* t = 2 */
      ColorType *color;
   } u;

In the case of the C++ interface model, all content items are added to the ShirtType class and the class is derived from the ProductType_derivations base class:

   class EXTERN ShirtType_2 : public OSXSDComplexType {
   public:
      // tag constants
      enum {
         T_size = 1,
         T_color = 2
      } ;
      OSUINT16 t;
      union {
         /* t = 1 */
         ::SizeType *size;
         /* t = 2 */
         ::ColorType *color;
      } u;
   ...
   } ;

   class EXTERN ShirtType : public ProductType_derivations {
   public:
      ::ProdNumType number;
      OSXMLStringClass name;
      ::ShirtType_2 _ext;

      ...
   } ;

   /**
    * Types derived from this base type:
    * ProductType
    * ShirtType
    */
   class EXTERN ProductType_derivations : public OSXSDComplexType {
   public:
      (no content)..
   } ;