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;   Derivations type: typedef struct BaseType_derivations { OSUINT16 t; union { /* t = 1 */ struct BaseType *baseType; /* t = 2 */ struct TypeName *typeName; } u; } BaseType_derivations;
Generated C++ code:	class TypeName : public BaseType_derivations { public: group type definition.. } ;   Derivations class: class BaseType_derivations : public OSXSDComplexType { public: BaseType_derivations () {} ... } ;

Notes:

1. group in the extension group definition above can be any content model group type (sequence, all, choice, or group).

2. In the case of C, the extension group is pulled out to form the temporary type (TypeName_2). The internals of this type depend on the content group type.

3. In the case of C++, 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_productType	1
 
#define T_ProductType_derivations_shirtType	2
 

 
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;
 

 

 

In the case of C++, 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)..
 
} ;