# WWW Related String Management

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

This module is like the generic string utility module but it contains more Web related string utility functions. Examples are functions that return a date string, a Message ID string etc.

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

    #ifndef HTWWWSTR_H
    #define HTWWWSTR_H

    #include "HTUser.h"
    #include "HTAtom.h"

## MIME Parsing and other String Based Utilities

A bunch of "finding the next whatever" functions.

### Next word or quoted string

This function returns a RFC822 word separated by space, comma, or semi-colons. `pstr` points to a string containing a word separated by white white space "," ";" or "=". The word can optionally be quoted using <"> or "<" ">" Comments surrrounded by '(' ')' are filtered out. On exit, `pstr` has been moved to the first delimiter past the field THE STRING HAS BEEN MUTILATED by a 0 terminator. The function returns a pointer to the first word or NULL on error

    extern char * HTNextField (char** pstr);

### Next Name-value Pair

This is the same as `HTNextField` but it does not look for '=' as a separator so if there is a name-value pair then both parts are returned. Returns a pointer to the first word or NULL on error

    extern char * HTNextPair (char ** pstr);

### Next Name-value Parameter

This is the same as `HTNextPair` but it does not look for ',' as a separator so if there is a name-value pair then both parts are returned. Returns a pointer to the first word or NULL on error

    extern char * HTNextParam (char ** pstr);

### Next LWS Delimited Token

A simpler version of the above that only looks for linear white space as the delimiter.

    extern char * HTNextLWSToken (char ** pstr);

### Find next "/" Delimited Segment

This is the same as HTNextField but it includes "/" as a delimiter. Returns a pointer to the first segment or NULL on error

    extern char * HTNextSegment (char ** pstr);

### Next Comma Separated String (or Element)

This is the same as HTNextPair but it does not look for anything else than ',' as separator Returns a pointer to the first word or NULL on error

    extern char * HTNextElement (char ** pstr);

### Next S-expression

Find the next s-expression token from a string of characters. We return the `name` of this expression and the `param` points to the parameters. Note, that the string has been mutilated by a 0 terminator!

    extern char * HTNextSExp (char ** exp, char ** param);

## Reading CRLF

The Library provides a default set of read routines that can handle the most common situations. However, before we start we make following definition is to make life easier when having a state machine looking for a `<CRLF>` sequence.

    typedef enum _HTEOLState {
        EOL_ERR = -1,
        EOL_BEGIN = 0,
        EOL_FCR,
        EOL_FLF,
        EOL_DOT,
        EOL_SCR,
        EOL_SLF,
        /* intermediate states */
        EOL_END,
        EOL_FOLD,
        EOL_LINE
    } HTEOLState;

## RFC1123 Date/Time Stamp String

Returns a string containing a date/time stamp string in RFC-1123 format. The string is in static memory so be aware!

    extern const char * HTDateTimeStr (time_t *calendar, BOOL local);

## Date used for directory listings

Generates a date/time stamp string used in directory listings. There is nothing special about this format, it is just to make directory listings look alike.

    extern BOOL HTDateDirStr (time_t * time, char * str, int len);

## Parse a Date/Time String

Converts a variety of different string representations of date time stamps in GMT to a local representation of localtime `time_t`. The local time zone is taken from the user profile information or directly from the system if `NULL` is passed as user profile . If the time is relative (for example in the `Age` header) then you can indicate whether it should be expanded to local time or not by using the `expand` argument.

    extern time_t HTParseTime (const char * str, HTUserProfile * up, BOOL expand);

## Unique Message-ID String

The message ID string can for example be use as a RFC 822 header. The content is based on the information taken from the user profile which can be supplied by the application.

    extern const char * HTMessageIdStr (HTUserProfile * up);

## Matching MIME Content-Types

Matches MIME constructions for content-types and others like them, for example "text/html", "text/plain". It can also match wild cards like "text/" and "/. We use instead of * in order note to make C like comments :-)

    extern BOOL HTMIMEMatch (HTAtom * tmplate, HTAtom * actual);

## Converts an Integer to a String using Prefix

In computer-world 1K is 1024 bytes and 1M is 1024K -- however, sprintf() still formats in base-10. Therefore I output only until 999, and then start using the next unit. This doesn't work wrong, it's just a feature. The conversion is done in "str" which must be large enough to contain the result.

    extern void HTNumToStr (unsigned long n, char *str, int len);

## Conversion between URLs and Local File Names

These are two functions that separate the URL naming syntax from platform dependent file naming schemes. If you are porting the code to a new platform, you probably have to do some translation here.

### Convert file URLs into a local representation

The URL has already been translated through the rules in get_physical in HTAccess.c and all we need to do now is to map the path to a local representation, for example if must translate '/' to the ones that turn the wrong way ;-) Returns local file (that must be freed by caller) if OK, else NULL.

    extern char * HTWWWToLocal (const char * url, const char * base,
    			    HTUserProfile * up);

### Convert a local file name into a URL

Generates a WWW URL name from a local file name or NULL if error. Returns URL (that must be freed by caller) if OK, else NULL. The access parameter can be used to indicate any special scheme used for local file access. If NULL then "`file:`" is used.

    extern char * HTLocalToWWW (const char * local, const char * access);

    #endif