PBDOM_OBJECT
The PBDOM_OBJECT class represents any node in an
XML node tree and serves as the base class for specialized PBDOM
classes that represent specific node types. The DOM class that corresponds
to PBDOM_OBJECT is the Node object. PBDOM_OBJECT
contains all the basic features required by derived classes. A node
can be an element node, a document node, or any of the node types
listed above that derive from PBDOM_OBJECT.
Methods
The PBDOM_OBJECT base class has the following methods:
-
AddContent, GetContent, InsertContent, RemoveContent,
and SetContent to allow you to manipulate the
children of the PBDOM_OBJECT -
Clone to allow you to make shallow
or deep clones of the PBDOM_OBJECT -
Detach to detach the PBDOM_OBJECT
from its parent -
Equals to test for equality with
another PBDOM_OBJECT -
GetName and SetName to
get and set the name of the PBDOM_OBJECT -
GetObjectClass and GetObjectClassString to
identify the class of the PBDOM_OBJECT -
GetOwnerDocumentObject to identify
the owner PBDOM_DOCUMENT of the current PBDOM_OBJECT -
GetParentObject and SetParentObject to
get and set the parent of the PBDOM_OBJECT -
GetText, GetTextNormalize,
and GetTextTrim to obtain the text data of the PBDOM_OBJECT -
HasChildren to determine whether
the PBDOM_OBJECT has any children -
IsAncestorObjectOf to determine
whether the PBDOM_OBJECT is the ancestor of another PBDOM_OBJECT
PBDOM_OBJECT inheritance
The PBDOM_OBJECT class is similar to a virtual class
in C++ in that it is not expected to be directly
instantiated and used. For example, although a PBDOM_OBJECT
can be created using the PowerScript CREATE statement, its
methods cannot be used directly:
|
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PBDOM_OBJECT pbdom_obj<br>pbdom_obj = CREATE PBDOM_OBJECT<br>pbdom_obj.SetName("VIRTUAL_PBDOM_OBJ") //exception! |
The
third line of code above throws an exception because it attempts
to directly access the SetName method for the
base class PBDOM_OBJECT. A similar implementation is valid,
however, when the SetName method is accessed
from a derived class, such as PBDOM_ELEMENT:
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PBDOM_OBJECT pbdom_obj<br>pbdom_obj = CREATE PBDOM_ELEMENT<br>pbdom_obj.SetName ("VIRTUAL_PBDOM_OBJ") |
Using the base PBDOM_OBJECT as a placeholder
The PBDOM_OBJECT class can be used as a placeholder
for an object of a derived class:
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PBDOM_DOCUMENT pbdom_doc<br>PBDOM_OBJECT pbdom_obj<br> <br>pbdom_doc = CREATE PBDOM_DOCUMENT<br>pbdom_doc.NewDocument ("", "", &<br>   "Root_Element_From_Doc_1", "", "")<br>pbdom_obj = pbdom_doc.GetRootElement<br>pbdom_obj.SetName &<br>   ("Root_Element_From_Doc_1_Now_Changed") |
The instantiated PBDOM_OBJECT pbdom_obj is
assigned to a PBDOM_DOCUMENT object, which holds the return
value of the GetRootElement method. Here, pbdom_obj holds
a reference to a PBDOM_ELEMENT and can be operated on legally
like any object of a class derived from PBDOM_OBJECT.
Standalone objects
A PBDOM_OBJECT can be created as a self-contained
object independent of any document or parent PBDOM_OBJECT.
Such a PBDOM_OBJECT is known as a standalone object. For
example:
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PBDOM_ELEMENT pbdom_elem_1<br>pbdom_elem_1 = Create PBDOM_ELEMENT<br>pbdom_elem_1.SetName("pbdom_elem_1") |
pbdom_elem_1 is instantiated
in the derived class PBDOM_ELEMENT using the Create keyword.
The SetName method can then be invoked from the pbdom_elem_1 object,
which is a standalone object not contained within any document.Standalone
objects can perform any legal PBDOM operations, but standalone status
does not give the object any special advantages or disadvantages.
Parent-owned and document-owned objects
A PBDOM_OBJECT can be assigned a parent by appending
it to another standalone PBDOM_OBJECT, as in the following
example:
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1 |
PBDOM_ELEMENT pbdom_elem_1<br>PBDOM_ELEMENT pbdom_elem_2<br> <br>pbdom_elem_1 = Create PBDOM_ELEMENT<br>pbdom_elem_2 = Create PBDOM_ELEMENT<br> <br>pbdom_elem_1.SetName("pbdom_elem_1")<br>pbdom_elem_2.SetName("pbdom_elem_2")<br>pbdom_elem_1.AddContent(pbdom_elem_2) |
Two PBDOM_ELEMENT objects, pbdom_elem_1 and pbdom_elem_2,
are instantiated. The pbdom_elem_2 object
is appended as a child object of pbdom_elem_1 using
the AddContent method. In this example, neither pbdom_elem_1 nor pbdom_elem_2 is
owned by any document, and the pbdom_elem_1 object
is still standalone. If pbdom_elem_1 were
assigned to a parent PBDOM_OBJECT owned by a document, pbdom_elem_1 would
cease to be a standalone object.