Representing a DOM node in ABL

In essence, X-document represents the collection of nodes, their content of the nodes, and all the relationships between nodes.

The X-noderef object is an ABL object that is a reference to any node in a DOM tree (except a DOCUMENT node, which is the X-document). In ABL, you can create a handle to an X-noderef object, which in turn is a cursor pointing to a DOM node in a DOM tree (represented by an ABL X-document object).

The life cycle of an X-noderef object is similar to the X-document object's. For example:

DEFINE VARIABLE hNode AS HANDLE NO-UNDO.
CREATE X-NODEREF hNode.
. . .
DELETE OBJECT hNode.

There are many types of DOM nodes as identified by the SUBTYPE attribute of both the X-document and X-noderef objects. Some types of nodes may have child nodes of various types, and others are leaf nodes that cannot have anything below them in the document structure.

The ABL X-noderef object can be one of the following DOM node types, as indicated by the SUBTYPE attribute:

ATTRIBUTE

CDATA-SECTION

COMMENT

DOCUMENT-FRAGMENT

ELEMENT

ENTITY-REFERENCE

PROCESSING-INSTRUCTION

TEXT

The default subtype is ELEMENT.

The following table shows X-noderef object SUBTYPE values, and how the NAME and NODE-VALUE attributes are different based on SUBTYPE.

Table 1. X-noderef SUBTYPE, NAME, and NODE-VALUE attributes
SUBTYPE attribute	NAME attribute	NODE-VALUE attribute
ATTRIBUTE	The name of the attribute. Primarily used with namespaces	The value of the attribute
DOCUMENT-FRAGMENT	Ignored	Content of the fragment
ELEMENT	XML tag name, including namespace information	Null
ENTITY-REFERENCE	The name of the entity referenced without the leading ampersand and trailing semicolon	Null
TEXT	Ignored	Content of the text node
CDATA-SECTION	Ignored	Content of the CDATA-SECTION
COMMENT	Ignored	Content of the COMMENT
PROCESSING-INSTRUCTION	The target, which is the first XML token following the <? markup	Content excluding the target