/*
 * $LynxId: SGML.h,v 1.47 2021/07/22 23:34:13 tom Exp $
 *			       SGML parse and stream definition for libwww
 *                             SGML AND STRUCTURED STREAMS
 *
 * The SGML parser is a state machine.	It is called for every character
 * of the input stream.	 The DTD data structure contains pointers
 * to functions which are called to implement the actual effect of the
 * text read. When these functions are called, the attribute structures pointed to by the
 * DTD are valid, and the function is passed a pointer to the current tag structure, and an
 * "element stack" which represents the state of nesting within SGML elements.
 *
 * The following aspects are from Dan Connolly's suggestions:  Binary search,
 * Structured object scheme basically, SGML content enum type.
 *
 * (c) Copyright CERN 1991 - See Copyright.html
 *
 */
#ifndef SGML_H
#define SGML_H

#include <HTStream.h>
#include <HTAnchor.h>
#include <LYJustify.h>

#ifdef __cplusplus
extern "C" {
#endif
/*
 *
 * SGML content types
 *
 */ typedef enum {
	SGML_EMPTY,		/* No content. */
	SGML_LITTERAL,		/* Literal character data.  Recognize exact close tag only.
				   Old www server compatibility only!  Not SGML */
	SGML_CDATA,		/* Character data.  Recognize </ only.
				   (But we treat it just as SGML_LITTERAL.) */
	SGML_SCRIPT,		/* Like CDATA, but allow it to be a comment */
	SGML_RCDATA,		/* Replaceable character data. Should recognize </ and &ref;
				   (but we treat it like SGML_MIXED for old times' sake). */
	SGML_MIXED,		/* Elements and parsed character data.
				   Recognize all markup. */
	SGML_ELEMENT,		/* Any data found should be regarded as an error.
				   (But we treat it just like SGML_MIXED.) */
	SGML_PCDATA		/* Should contain no elements but &ref; is parsed.
				   (We treat it like SGML_CDATA wrt. contained tags
				   i.e. pass them on literally, i.e. like we should
				   treat SGML_RCDATA) (added by KW). */
    } SGMLContent;

    typedef struct {
	const char *name;	/* The name of the attribute */
#ifdef USE_PRETTYSRC
	char type;		/* code of the type of the attribute. Code
				   values are in HTMLDTD.h */
#endif
    } attr;

    typedef const attr *AttrList;

    typedef struct {
	const char *name;
	AttrList list;
    } AttrType;

    typedef int TagClass;

    /* textflow */
#define Tgc_FONTlike	0x00001	/* S,STRIKE,I,B,TT,U,BIG,SMALL,STYLE,BLINK;BR,TAB */
#define Tgc_EMlike	0x00002	/* EM,STRONG,DFN,CODE,SAMP,KBD,VAR,CITE,Q,INS,DEL,SPAN,.. */
#define Tgc_MATHlike	0x00004	/* SUB,SUP,MATH,COMMENT */
#define Tgc_Alike	0x00008	/* A */
#define Tgc_formula	0x00010	/* not used until math is supported better... */
    /* used for special structures: forms, tables,... */
#define Tgc_TRlike	0x00020	/* TR and similar */
#define Tgc_SELECTlike	0x00040	/* SELECT,INPUT,TEXTAREA(,...) */
    /* structure */
#define Tgc_FORMlike	0x00080	/* FORM itself */
#define Tgc_Plike	0x00100	/* P,H1..H6,... structures containing text or
				   insertion but not other structures */
#define Tgc_DIVlike	0x00200	/* ADDRESS,FIG,BDO,NOTE,FN,DIV,CENTER;FIG
				   structures which can contain other structures */
#define Tgc_LIlike	0x00400	/* LH,LI,DT,DD;TH,TD structure-like, only valid
				   within certain other structures */
#define Tgc_ULlike	0x00800	/* UL,OL,DL,DIR,MENU;TABLE;XMP,LISTING
				   special in some way, cannot contain (parsed)
				   text directly */
    /* insertions */
#define Tgc_BRlike	0x01000	/* BR,IMG,TAB allowed in any text */
#define Tgc_APPLETlike	0x02000	/* APPLET,OBJECT,EMBED,SCRIPT;BUTTON */
#define Tgc_HRlike	0x04000	/* HR,MARQUEE can contain all kinds of things
				   and/or are not allowed (?) in running text */
#define Tgc_MAPlike	0x08000	/* MAP,AREA some specials that never contain
				   (directly or indirectly) other things than
				   special insertions */
#define Tgc_outer	0x10000	/* HTML,FRAMESET,FRAME,PLAINTEXT; */
#define Tgc_BODYlike	0x20000	/* BODY,BODYTEXT,NOFRAMES,TEXTFLOW; */
#define Tgc_HEADstuff	0x40000	/* HEAD,BASE,STYLE,TITLE; */
    /* special relations */
#define Tgc_same	0x80000
#define Tgc_DELlike	0x100000
    /* DELlike is a class of aliases for inline DEL/INS */
    typedef unsigned char TagAlias;

/*
 * Groups for contains-data.
 */
#define Tgc_INLINElike	(Tgc_Alike | Tgc_APPLETlike | Tgc_BRlike | Tgc_EMlike | Tgc_FONTlike | Tgc_SELECTlike)
#define Tgc_LISTlike	(Tgc_LIlike | Tgc_ULlike)
#define Tgc_BLOCKlike	(Tgc_DIVlike | Tgc_LISTlike)

/* Some more properties of tags (or rather, elements) and rules how
   to deal with them. - kw */
    typedef int TagFlags;

#define Tgf_endO	0x00001	/* end tag can be Omitted */
#define Tgf_startO	0x00002	/* start tag can be Omitted */
#define Tgf_mafse	0x00004	/* Make Attribute-Free Start-tag End instead
				   (if found invalid) */
#define Tgf_strict	0x00008	/* Ignore contained invalid elements,
				   don't pass them on; or other variant
				   handling for some content types */
#define Tgf_nreie	0x00010	/* Not Really Empty If Empty,
				   used by color style code */
#define Tgf_frecyc	0x00020	/* Pass element content on in a form that
				   allows recycling, i.e. don't translate to
				   output (display) character set yet (treat
				   content similar to attribute values) */
#define Tgf_nolyspcl	0x00040	/* Don't generate lynx special characters
				   for soft hyphen and various spaces (nbsp,
				   ensp,..) */

/*		A tag structure describes an SGML element.
 *		-----------------------------------------
 *
 *
 *	name		is the string which comes after the tag opener "<".
 *
 *	attributes	points to a zero-terminated array
 *			of attribute names.
 *
 *	litteral	determines how the SGML engine parses the characters
 *			within the element.  If set, tag openers are ignored
 *			except for that which opens a matching closing tag.
 *
 */
    typedef struct _tag HTTag;
    struct _tag {
	const char *name;	/* The name of the tag */
#ifdef USE_COLOR_STYLE
	unsigned name_len;	/* The length of the name */
#endif
#ifdef USE_JUSTIFY_ELTS
	BOOL can_justify;	/* justification allowed? */
#endif
	AttrList attributes;	/* The list of acceptable attributes */
	int number_of_attributes;	/* Number of possible attributes */
	const AttrType *attr_types;
	SGMLContent contents;	/* End only on end tag @@ */
	TagClass tagclass;
	TagClass contains;	/* which classes of elements this one can contain directly */
	TagClass icontains;	/* which classes of elements this one can contain indirectly */
	TagClass contained;	/* in which classes can this tag be contained ? */
	TagClass icontained;	/* in which classes can this tag be indirectly contained ? */
	TagClass canclose;	/* which classes of elements can this one close
				   if something looks wrong ? */
	TagFlags flags;
	TagAlias alias;		/* extra levels, e.g, DEL/INS */
	TagAlias aliases;	/* number of extra levels, e.g, DEL/INS */
    };

/*		DTD Information
 *		---------------
 *
 *  Not the whole DTD, but all this parser uses of it.
 */
    typedef struct {
	HTTag *tags;		/* Must be in strcmp order by name */
	int number_of_tags;
	STRING2PTR entity_names;	/* Must be in strcmp order by name */
	size_t number_of_entities;
	/*  "entity_names" table probably unused,
	 *  see comments in HTMLDTD.c near the top
	 */
    } SGML_dtd;

/*	SGML context passed to parsers
*/
    typedef struct _HTSGMLContext *HTSGMLContext;	/* Hidden */

/*__________________________________________________________________________
*/

/*

Structured Object definition

   A structured object is something which can reasonably be represented
   in SGML.  I'll rephrase that.  A structured object is an ordered
   tree-structured arrangement of data which is representable as text.
   The SGML parser outputs to a Structured object.  A Structured object
   can output its contents to another Structured Object.  It's a kind of
   typed stream.  The architecture is largely Dan Conolly's.  Elements and
   entities are passed to the sob by number, implying a knowledge of the
   DTD.	 Knowledge of the SGML syntax is not here, though.

   Superclass: HTStream

   The creation methods will vary on the type of Structured Object.
   Maybe the callerData is enough info to pass along.

 */
    typedef struct _HTStructured HTStructured;

    typedef struct _HTStructuredClass {

	const char *name;	/* Just for diagnostics */

	void (*_free) (HTStructured * me);

	void (*_abort) (HTStructured * me, HTError e);

	void (*put_character) (HTStructured * me, int ch);

	void (*put_string) (HTStructured * me, const char *str);

	void (*put_block) (HTStructured * me, const char *str, int len);

	/* HTStreamClass ends here */

	int (*start_element) (HTStructured * me, int element_number,
			      const BOOL *attribute_present,
			      STRING2PTR attribute_value,
			      int charset,
			      char **include);

	int (*end_element) (HTStructured * me, int element_number,
			    char **include);

	int (*put_entity) (HTStructured * me, int entity_number);

    } HTStructuredClass;

/*
  Equivalents to the following functions possibly could be generalised
  into additional HTStructuredClass members.  For now they don't do
  anything target-specific. - kw
  */
    extern BOOLEAN LYCheckForCSI(HTParentAnchor *anchor, char **url);
    extern void LYDoCSI(char *url, const char *comment, char **csi);
    extern BOOLEAN LYCommentHacks(HTParentAnchor *anchor, const char *comment);

/*

Find a Tag by Name

   Returns a pointer to the tag within the DTD.

 */
    extern HTTag *SGMLFindTag(const SGML_dtd * dtd,
			      const char *string);

/*
 * Return the current offset within the file that SGML is parsing
 */
    extern int SGML_offset(void);

/*

Create an SGML parser

 */
/*
 * On entry,
 *	dtd		must point to a DTD structure as defined above
 *	callbacks	must point to user routines.
 *	callData	is returned in callbacks transparently.
 * On exit,
 *		The default tag starter has been processed.
 */
    extern HTStream *SGML_new(const SGML_dtd * dtd,
			      HTParentAnchor *anchor,
			      HTStructured * target);

    extern const HTStreamClass SGMLParser;

#ifdef __cplusplus
}
#endif
#endif				/* SGML_H */
