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/* HTFormat: The format manager in the WWW Library
MANAGE DIFFERENT DOCUMENT FORMATS
Here we describe the functions of the HTFormat module which handles conversion between
different data representations. (In MIME parlance, a representation is known as a
content-type. In WWW the term "format" is often used as it is shorter).
This module is implemented by HTFormat.c . This hypertext document is used to generate
the HTFormat.h include file. Part of the WWW library .
Preamble
*/
#ifndef HTFORMAT_H
#define HTFORMAT_H
#ifndef HTUTILS_H
#include "HTUtils.h"
#endif /* HTUTILS_H */
#include "HTStream.h"
#include "HTAtom.h"
#include "HTList.h"
#ifdef SHORT_NAMES
#define HTOutputSource HTOuSour
#define HTOutputBinary HTOuBina
#endif
/*
The HTFormat type
We use the HTAtom object for holding representations. This allows faster manipulation
(comparison and copying) that if we stayed with strings.
*/
typedef HTAtom * HTFormat;
/*
These macros (which used to be constants) define some basic internally referenced
representations. The www/xxx ones are of course not MIME standard.
www/source is an output format which leaves the input untouched. It is useful for
diagnostics, and for users who want to see the original, whatever it is.
*/
/* Internal ones */
#define WWW_SOURCE HTAtom_for("www/source") /* Whatever it was originally*/
/*
www/present represents the user's perception of the document. If you convert to
www/present, you present the material to the user.
*/
#define WWW_PRESENT HTAtom_for("www/present") /* The user's perception */
/*
The message/rfc822 format means a MIME message or a plain text message with no MIME
header. This is what is returned by an HTTP server.
*/
#define WWW_MIME HTAtom_for("www/mime") /* A MIME message */
/*
www/print is like www/present except it represents a printed copy.
*/
#define WWW_PRINT HTAtom_for("www/print") /* A printed copy */
/*
www/unknown is a really unknown type. Some default action is appropriate.
*/
#define WWW_UNKNOWN HTAtom_for("www/unknown")
#ifdef DIRED_SUPPORT
/*
www/dired signals directory edit mode.
*/
#define WWW_DIRED HTAtom_for("www/dired")
#endif
/*
These are regular MIME types. HTML is assumed to be added by the W3 code.
application/octet-stream was mistakenly application/binary in earlier libwww versions
(pre 2.11).
*/
#define WWW_PLAINTEXT HTAtom_for("text/plain")
#define WWW_POSTSCRIPT HTAtom_for("application/postscript")
#define WWW_RICHTEXT HTAtom_for("application/rtf")
#define WWW_AUDIO HTAtom_for("audio/basic")
#define WWW_HTML HTAtom_for("text/html")
#define WWW_BINARY HTAtom_for("application/octet-stream")
/*
We must include the following file after defining HTFormat, to which it makes
reference.
The HTEncoding type
*/
typedef HTAtom* HTEncoding;
/*
The following are values for the MIME types:
*/
#define WWW_ENC_7BIT HTAtom_for("7bit")
#define WWW_ENC_8BIT HTAtom_for("8bit")
#define WWW_ENC_BINARY HTAtom_for("binary")
/*
We also add
*/
#define WWW_ENC_COMPRESS HTAtom_for("compress")
#include "HTAnchor.h"
/*
The HTPresentation and HTConverter types
This HTPresentation structure represents a possible conversion algorithm from one
format to annother. It includes a pointer to a conversion routine. The conversion
routine returns a stream to which data should be fed. See also HTStreamStack which
scans the list of registered converters and calls one. See the initialisation module
for a list of conversion routines.
*/
typedef struct _HTPresentation HTPresentation;
typedef HTStream * HTConverter PARAMS((
HTPresentation * pres,
HTParentAnchor * anchor,
HTStream * sink));
struct _HTPresentation {
HTAtom * rep; /* representation name atmoized */
HTAtom * rep_out; /* resulting representation */
HTConverter * converter; /* The routine to gen the stream stack */
char * command; /* MIME-format string */
float quality; /* Between 0 (bad) and 1 (good) */
float secs;
float secs_per_byte;
long int maxbytes;
};
/*
The list of presentations is kept by this module. It is also scanned by modules which
want to know the set of formats supported. for example.
*/
extern HTList * HTPresentations;
/*
The default presentation is used when no other is appriporate
*/
extern HTPresentation* default_presentation;
/*
HTSetPresentation: Register a system command to present a format
ON ENTRY,
rep is the MIME - style format name
command is the MAILCAP - style command template
quality A degradation faction 0..1.0
secs A limit on the time user will wait (0.0 for infinity)
secs_per_byte
maxbytes A limit on the length acceptable as input (0 infinite)
*/
extern void HTSetPresentation PARAMS((
CONST char * representation,
CONST char * command,
float quality,
float secs,
float secs_per_byte,
long int maxbytes
));
/*
HTSetConversion: Register a converstion routine
ON ENTRY,
rep_in is the content-type input
rep_out is the resulting content-type
converter is the routine to make the stream to do it
*/
extern void HTSetConversion PARAMS((
CONST char * rep_in,
CONST char * rep_out,
HTConverter * converter,
float quality,
float secs,
float secs_per_byte,
long int maxbytes
));
/*
HTStreamStack: Create a stack of streams
This is the routine which actually sets up the conversion. It currently checks only for
direct conversions, but multi-stage conversions are forseen. It takes a stream into
which the output should be sent in the final format, builds the conversion stack, and
returns a stream into which the data in the input format should be fed. The anchor is
passed because hypertxet objects load information into the anchor object which
represents them.
*/
extern HTStream * HTStreamStack PARAMS((
HTFormat format_in,
HTFormat format_out,
HTStream* stream_out,
HTParentAnchor* anchor));
/*
HTStackValue: Find the cost of a filter stack
Must return the cost of the same stack which HTStreamStack would set up.
ON ENTRY,
format_in The fomat of the data to be converted
format_out The format required
initial_value The intrinsic "value" of the data before conversion on a scale
from 0 to 1
length The number of bytes expected in the input format
*/
extern float HTStackValue PARAMS((
HTFormat format_in,
HTFormat rep_out,
float initial_value,
long int length));
#define NO_VALUE_FOUND -1e20 /* returned if none found */
/*
HTCopy: Copy a socket to a stream
This is used by the protocol engines to send data down a stream, typically one which
has been generated by HTStreamStack.
*/
extern int HTCopy PARAMS((
HTParentAnchor * anchor,
int file_number,
void* handle,
HTStream* sink));
/*
HTFileCopy: Copy a file to a stream
This is used by the protocol engines to send data down a stream, typically one which
has been generated by HTStreamStack. It is currently called by HTParseFile
*/
extern int HTFileCopy PARAMS((
FILE* fp,
HTStream* sink));
/*
HTCopyNoCR: Copy a socket to a stream, stripping CR characters.
It is slower than HTCopy .
*/
extern void HTCopyNoCR PARAMS((
HTParentAnchor * anchor,
int file_number,
HTStream* sink));
/*
Clear input buffer and set file number
This routine and the one below provide simple character input from sockets. (They are
left over from the older architecure and may not be used very much.) The existence of
a common routine and buffer saves memory space in small implementations.
*/
extern void HTInitInput PARAMS((int file_number));
/*
Get next character from buffer
*/
extern char HTGetCharacter NOPARAMS;
/*
HTParseSocket: Parse a socket given its format
This routine is called by protocol modules to load an object. uses HTStreamStack and
the copy routines above. Returns HT_LOADED if succesful, <0 if not.
*/
extern int HTParseSocket PARAMS((
HTFormat format_in,
HTFormat format_out,
HTParentAnchor *anchor,
int file_number,
HTStream* sink));
/*
HTParseFile: Parse a File through a file pointer
This routine is called by protocols modules to load an object. uses HTStreamStack and
HTFileCopy . Returns HT_LOADED if succesful, <0 if not.
*/
extern int HTParseFile PARAMS((
HTFormat format_in,
HTFormat format_out,
HTParentAnchor *anchor,
FILE *fp,
HTStream* sink));
/*
HTNetToText: Convert Net ASCII to local representation
This is a filter stream suitable for taking text from a socket and passing it into a
stream which expects text in the local C representation. It does ASCII and newline
conversion. As usual, pass its output stream to it when creating it.
*/
extern HTStream * HTNetToText PARAMS ((HTStream * sink));
/*
HTFormatInit: Set up default presentations and conversions
These are defined in HTInit.c or HTSInit.c if these have been replaced. If you don't
call this routine, and you don't define any presentations, then this routine will
automatically be called the first time a conversion is needed. However, if you
explicitly add some conversions (eg using HTLoadRules) then you may want also to
explicitly call this to get the defaults as well.
*/
extern void HTFormatInit NOPARAMS;
/*
Epilogue
*/
extern BOOL HTOutputSource; /* Flag: shortcut parser */
#endif
/*
end */
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