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