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Delphi Wrapper Classes and XML


In this article we will look at a partial listing of the xmlintf unit and then write a program to demonstrate how to use DOM in Delphi. We began our discussion of this topic in the previous article. This is part three of a four-part series.

Author Info:
By: David Web
Rating: 5 stars5 stars5 stars5 stars5 stars / 7
November 17, 2008
TABLE OF CONTENTS:
  1. · Delphi Wrapper Classes and XML
  2. · XML Properties, Methods, and Interface
  3. · A Demonstration
  4. · Second Part of Code

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Delphi Wrapper Classes and XML
(Page 1 of 4 )

Below is a listing of the xmlintf unit that we discussed in the previous article. It is one of the main XML units that form part of the wrapper classes in Delphi. I will only show the functions, procedures and properties definitions and not their implementation, because it would fill the entire article if I did:


unit XMLIntf;


interface


{$IFDEF MSWINDOWS}

{ MSXML.H defines another IXMLDocument and references the type...

The compiler must see this before it sees the IXMLDocument

introduced in this unit - otherwise, references will cause

ambiguity errors }

(*$HPPEMIT '#include <msxml.h>' *)

{$ENDIF}


uses SysUtils, Classes, xmldom;


type


{ Data types }


TNodeType = (ntReserved, ntElement, ntAttribute, ntText, ntCData,

ntEntityRef, ntEntity, ntProcessingInstr, ntComment, ntDocument,

ntDocType, ntDocFragment, ntNotation);


{ Forward Declarations }


IXMLNode = interface;

IXMLNodeList = interface;

IXMLNodeCollection = interface;

IXMLDocument = interface;


{ EXMLDocError }


EXMLDocError = class(Exception)

end;


{ IXMLNode }


IXMLNode = interface

['{395950C0-7E5D-11D4-83DA-00C04F60B2DD}']

{ Property Accessors }

function GetAttribute(const AttrName: DOMString): OleVariant;

function GetAttributeNodes: IXMLNodeList;

function GetChildNodes: IXMLNodeList;

function GetChildValue(const IndexOrName: OleVariant): OleVariant;

function GetCollection: IXMLNodeCollection;

function GetDOMNode: IDOMNode;

function GetHasChildNodes: Boolean;

function GetIsTextElement: Boolean;

function GetLocalName: DOMString;

function GetNamespaceURI: DOMString;

function GetNodeName: DOMString;

function GetNodeType: TNodeType;

function GetNodeValue: OleVariant;

function GetOwnerDocument: IXMLDocument;

function GetParentNode: IXMLNode;

function GetPrefix: DOMString;

function GetReadOnly: Boolean;

function GetText: DOMString;

function GetXML: DOMString;

procedure SetAttribute(const AttrName: DOMString; const Value: OleVariant);

procedure SetChildValue(const IndexOrName: OleVariant; const Value: OleVariant);

procedure SetNodeValue(const Value: OleVariant);

procedure SetReadOnly(const Value: Boolean);

procedure SetText(const Value: DOMString);

{ Methods }

function AddChild(const TagName: DOMString; Index: Integer = -1): IXMLNode; overload;

function AddChild(const TagName, NamespaceURI: DOMString;

GenPrefix: Boolean = False; Index: Integer = -1): IXMLNode; overload;

function CloneNode(Deep: Boolean): IXMLNode;

procedure DeclareNamespace(const Prefix, URI: DOMString);

function FindNamespaceURI(const TagOrPrefix: DOMString): DOMString;

function FindNamespaceDecl(const NamespaceURI: DOMString): IXMLNode;

function GetAttributeNS(const AttrName, NamespaceURI: DOMString): OleVariant;

function HasAttribute(const Name: DOMString): Boolean; overload;

function HasAttribute(const Name, NamespaceURI: DOMString): Boolean; overload;

function NextSibling: IXMLNode;

procedure Normalize;

function PreviousSibling: IXMLNode;

procedure Resync;

procedure SetAttributeNS(const AttrName, NamespaceURI: DOMString; const Value: OleVariant);

procedure TransformNode(const stylesheet: IXMLNode; var output: WideString); overload;

procedure TransformNode(const stylesheet: IXMLNode; const output: IXMLDocument); overload;


The functions and procedures above define some of the elements that make up the wrapper class. Below are the properties and attributes of the class:

{ Properties }

property Attributes[const AttrName: DOMString]: OleVariant read GetAttribute write SetAttribute;

property AttributeNodes: IXMLNodeList read GetAttributeNodes;

property ChildNodes: IXMLNodeList read GetChildNodes;

property ChildValues[const IndexOrName: OleVariant]: OleVariant read GetChildValue write SetChildValue; default;

property Collection: IXMLNodeCollection read GetCollection;

property DOMNode: IDOMNode read GetDOMNode;

property OwnerDocument: IXMLDocument read GetOwnerDocument;

property HasChildNodes: Boolean read GetHasChildNodes;

property IsTextElement: Boolean read GetIsTextElement;

property LocalName: DOMString read GetLocalName;

property NamespaceURI: DOMString read GetNameSpaceURI;

property NodeName: DOMstring read GetNodeName;

property NodeType: TNodeType read GetNodeType;

property NodeValue: OleVariant read GetNodeValue write SetNodeValue;

property ParentNode: IXMLNode read GetParentNode;

property Prefix: DOMString read GetPrefix;

property ReadOnly: Boolean read GetReadOnly write SetReadOnly;

property Text: DOMString read GetText write SetText;

property XML: DOMString read GetXML;

end;


{ IXMLNodeList }


Below I've defined the interface to the XML wrapper class. It will be used by the other classes and units to interface. The methods and properties are also defined:

IXMLNodeList = interface

['{395950C1-7E5D-11D4-83DA-00C04F60B2DD}']

{ Property Accessors }

function GetCount: Integer;

function GetNode(const IndexOrName: OleVariant): IXMLNode;

function GetUpdateCount: Integer;

{ Methods }

function Add(const Node: IXMLNode): Integer;

procedure BeginUpdate;

procedure Clear;

function Delete(const Index: Integer): Integer; overload;

function Delete(const Name: DOMString): Integer; overload;

function Delete(const Name, NamespaceURI: DOMString): Integer; overload;

procedure EndUpdate;

function First: IXMLNode;

function FindNode(NodeName: DOMString): IXMLNode; overload;

function FindNode(NodeName, NamespaceURI: DOMString): IXMLNode; overload;

function FindNode(ChildNodeType: TGuid): IXMLNode; overload;

function FindSibling(const Node: IXMLNode; Delta: Integer): IXMLNode;

function Get(Index: Integer): IXMLNode;

function IndexOf(const Node: IXMLNode): Integer; overload;

function IndexOf(const Name: DOMString): Integer; overload;

function IndexOf(const Name, NamespaceURI: DOMString): Integer; overload;

procedure Insert(Index: Integer; const Node: IXMLNode);

function Last: IXMLNode;

function Remove(const Node: IXMLNode): Integer;

function ReplaceNode(const OldNode, NewNode: IXMLNode): IXMLNode;

{ Properties }

property Count: Integer read GetCount;

property Nodes[const IndexOrName: OleVariant]: IXMLNode read GetNode; default;

property UpdateCount: Integer read GetUpdateCount;

end;


The XMLnode collection interface is then created:


{ IXMLNodeCollection }


IXMLNodeCollection = interface(IXMLNode)

['{395950C2-7E5D-11D4-83DA-00C04F60B2DD}']

{ Property Accessors }

function GetCount: Integer;

function GetNode(Index: Integer): IXMLNode;

{ Public properties }

procedure Clear;

procedure Delete(Index: Integer);

function Remove(const Node: IXMLNode): Integer;

property Count: Integer read GetCount;

property Nodes[Index: Integer]: IXMLNode read GetNode; default;

end;


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