The HTML to styled text object converter

/*
**	(c) COPYRIGHT CERN 1994.
**	Please first read the full copyright statement in the file COPYRIGH.
*/
This interprets the HTML semantics and some HTMLPlus.

This module is implemented by HTML.c, and it is a part of the Library of Common Code. 

#ifndef HTML_H
#define HTML_H

#include "HTFormat.h"
#include "HTAnchor.h"
#include "HTMLPDTD.h"

#define DTD HTMLP_dtd

#ifdef SHORT_NAMES
#define HTMLPresentation 	HTMLPren
#define HTMLPresent		HTMLPres
#endif

extern CONST HTStructuredClass HTMLPresentation;

HTML_new: A structured stream to parse HTML

When this routine is called, the request structure may contain a childAnchor value. In that case it is the responsability of this module to select the anchor.

extern HTStructured* HTML_new PARAMS((HTRequest * request,
					void *   param,
					HTFormat input_format,
					HTFormat output_format,
				     	HTStream * output_stream));

Reopen

Reopening an existing HTML object allows it to be retained (for example by the styled text object) after the structured stream has been closed. To be actually deleted, the HTML object must be closed once more times than it has been reopened. 
extern void HTML_reopen PARAMS((HTStructured * me));

Converters

These are the converters implemented in this module: 
#ifndef pyramid
extern HTConverter HTMLToPlain, HTMLToC, HTMLPresent, HTMLToTeX;
#endif

Selecting internal character set representations

typedef enum _HTMLCharacterSet {
	HTML_ISO_LATIN1,
	HTML_NEXT_CHARS,
	HTML_PC_CP950
} HTMLCharacterSet;

extern void HTMLUseCharacterSet PARAMS((HTMLCharacterSet i));

Record error message as a hypertext object

The error message should be marked as an error so that it can be reloaded later. This implementation just throws up an error message and leaves the document unloaded.

On entry,

sink
is a stream to the output device if any
number
is the HTTP error number
message
is the human readable message.

On exit,

a return code like HT_LOADED if object exists else < 0 
extern int HTLoadError PARAMS((
	HTRequest * 	req,
	int		number,
	CONST char *	message));

White Space Treatment

There is a small number of different ways of treating white space in SGML, in mapping from a text object to HTML. These have to be programmed it seems. 
/*
In text object	\n\n		\n	tab	\n\n\t
--------------	-------------	-----	-----	-------
in Address,
Blockquote,
Normal,		<P>		<BR>	-		NORMAL
H1-6:		close+open	<BR>	-		HEADING
Glossary	<DT>		<DT>	<DD>	<P>	GLOSSARY
List,				
Menu		<LI>		<LI>	-	<P>	LIST
Dir		<LI>		<LI>	<LI>		DIR
Pre etc		\n\n		\n	\t		PRE

*/

typedef enum _white_space_treatment {
	WS_NORMAL,
	WS_HEADING,
	WS_GLOSSARY,
	WS_LIST,
	WS_DIR,
	WS_PRE
} white_space_treatment;

Nesting State

These elements form tree with an item for each nesting state: that is, each unique combination of nested elements which has a specific style. 
typedef struct _HTNesting {
    void *			style;  /* HTStyle *: Platform dependent */
    white_space_treatment	wst;
    struct _HTNesting *		parent;
    int				element_number;
    int				item_number;	/* only for ordered lists */
    int				list_level;	/* how deep nested */
    HTList *			children;
    BOOL			paragraph_break;
    int				magic;
    BOOL			object_gens_HTML; /* we don't generate HTML */
} HTNesting;

Nesting functions

These functions were new with HTML2.c. They allow the tree of SGML nesting states to be manipulated, and SGML regenerated from the style sequence. 

extern void HTRegenInit NOPARAMS;

extern void HTRegenCharacter PARAMS((
	char			c,
	HTNesting *		nesting,
	HTStructured *		target));

extern	void HTNestingChange PARAMS((
	HTStructured* 	s, 
	HTNesting*		old, 
	HTNesting *		newnest,
	HTChildAnchor *		info,
	CONST char *		aName));

extern HTNesting * HTMLCommonality PARAMS((
	HTNesting * 	s1,
	HTNesting *	s2));

extern HTNesting * HTNestElement PARAMS((HTNesting * p, int ele));
extern /* HTStyle * */ void * HTStyleForNesting PARAMS((HTNesting * n));

extern HTNesting* HTMLAncestor PARAMS((HTNesting * old, int depth));

extern HTNesting* CopyBranch PARAMS((HTNesting * old, HTNesting * newnest,
				     int depth));

extern HTNesting * HTInsertLevel PARAMS((HTNesting * old,
		int	element_number,
		int	level));
extern HTNesting * HTDeleteLevel PARAMS((HTNesting * old,
		int	level));
extern int HTMLElementNumber PARAMS((HTNesting * s));
extern int HTMLLevel PARAMS(( HTNesting * s));
extern HTNesting* HTMLAncestor PARAMS((HTNesting * old, int depth));

#endif		/* end HTML_H */
end