htlink.h

www工具包

/*

  
  					W3C Sample Code Library libwww Link Class


!
  The Link Class
!
*/

/*
**	(c) COPYRIGHT MIT 1995.
**	Please first read the full copyright statement in the file COPYRIGH.
*/

/*

A Link represents the link between anchor objects.
By keeping the link as a object and not as part of the anchor we are capable
of handling link semantics in a much more organized way. For example, we
can then search for link types among all the link objects that we have created.
Anchor objects are bound together using Link
objects. Each anchor can be the source or destination of zero, one, or more
links from and to other anchors.

This module is implemented by HTLink.c, and it is
a part of the  W3C Sample Code
Library.
*/

#ifndef HTLINK_H
#define HTLINK_H

typedef struct _HTLink	HTLink;

#include "WWWUtil.h"
#include "HTMethod.h"
#include "HTAnchor.h"

/*
.
  Creation and Deletion Methods
.

These are the methods for crating and deleting new link objects
(
  Create a new Link Object
)
*/
typedef HTAtom * 	HTLinkType;

typedef enum _HTLinkResult {
    HT_LINK_INVALID = -1,
    HT_LINK_NONE = 0,
    HT_LINK_ERROR,
    HT_LINK_OK
} HTLinkResult;

struct _HTLink {
    HTAnchor *		dest;		   /* The anchor to which this leads */
    HTLinkType		type;		           /* Semantics of this link */
    HTMethod		method;		   /* Method for this link, e.g. PUT */
    HTLinkResult	result;    /* Result of any attempt to get this link */
};

HTLink * HTLink_new (void);

/*
(
  Delete a Link Object
)

A link can be removed as any other object
*/
BOOL HTLink_delete (HTLink * link);

/*
(
  Remove All Link Information from an Anchor
)

This is normally a part of deleting anchor objects.
*/
extern BOOL HTLink_removeAll (HTAnchor * me);

/*
.
  Handle Link Between Anchors
.

As mentioned, link objects are the ones that bind anchor objects together
in a Web like structure
(
  Add a Link between two Anchors
)

This method creates a new link between two anchor
objects.
*/
extern BOOL HTLink_add (HTAnchor *	source,
			     HTAnchor * destination, 
			     HTLinkType	type,
			     HTMethod	method);

/*
(
  Remove All Links Between two Anchors
)

Removes link information from one anchor to another.
*/
extern BOOL HTLink_remove (HTAnchor * source, HTAnchor * destination);

/*
(
  Find a Link
)

Find the anchor object between a destination and a source ancher. Return
link object if any, else NULL
*/
extern HTLink * HTLink_find (HTAnchor * source, HTAnchor * destination);

/*
.
  Link Information
.

This is the set of methods for accessing the information carried by a link
object
(
  Link Destination
)

The link destination is the destination anchor pointed to by the link.
*/
extern BOOL HTLink_setDestination (HTLink * link, HTAnchor * dest);
extern HTAnchor * HTLink_destination (HTLink * link);

/*
(
  Link Types and Semantic Links
)

Each link has a sematic representation associated with it. This means that
the application can distinguish between pages based on the semantics of the
link. This is very similar to the LINK tag in HTML pages which
indicates the meaning if this pages to other pages.
*/
extern BOOL HTLink_setType (HTLink * link, HTLinkType type);
extern HTLinkType HTLink_type (HTLink * link);

/*
(
  Link Method
)

The link method is the HTTP method we have performed between the two links.
For example, it can be a POST operation, or a PUT operation where the operation
on the first anchor created a new anchor.
*/
extern BOOL HTLink_setMethod (HTLink * link, HTMethod method);
extern HTMethod HTLink_method (HTLink * link);

/*
(
  Link Result
)

When a link has been used for posting an object from a source to a destination
link, the result of the operation is stored as part of the link information.
This means that we can keep track of which operations we have performed on
a link and hence the application can ask the user whether he or she wants
to do a re-post, for example.
*/

extern BOOL HTLink_setResult (HTLink * link, HTLinkResult result);
extern HTLinkResult HTLink_result (HTLink * link);

/*
*/

#endif /* HTLINK_H */

/*

  

  @(#) $Id: HTLink.html,v 2.3 1998/05/14 02:10:38 frystyk Exp $

*/