windows-server-2003/inetcore/wininet/dll/strtokex.c

/***
*strtokex.c - tokenize a string with given delimiters
*
*       Copyright (c) 1989-1993, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines strtok() - breaks string into series of token
*       via repeated calls.
*
*******************************************************************************/
#if defined(unix)
#define __cdecl
#endif
#include <string.h>
/***
*char *StrTokEx(pstring, control) - tokenize string with delimiter in control
*
*Purpose:
*       StrTokEx considers the string to consist of a sequence of zero or more
*       text tokens separated by spans of one or more control chars. the first
*       call, with string specified, returns a pointer to the first char of the
*       first token, and will write a null char into pstring immediately
*       following the returned token. when no tokens remain
*       in pstring a NULL pointer is returned. remember the control chars with a
*       bit map, one bit per ascii char. the null char is always a control char.
*
*Entry:
*       char **pstring - ptr to ptr to string to tokenize
*       char *control - string of characters to use as delimiters
*
*Exit:
*       returns pointer to first token in string,
*       returns NULL when no more tokens remain.
*       pstring points to the beginning of the next token.
*
*WARNING!!!
*       upon exit, the first delimiter in the input string will be replaced with '\0'
*
*******************************************************************************/
char * __cdecl StrTokEx (char ** pstring, const char * control)
{
        /*unsigned*/ char *str;
        const /*unsigned*/ char *ctrl = control;
        unsigned char map[32];
        int count;

        char *tokenstr;

        if(*pstring == NULL)
            return NULL;

        /* Clear control map */
        for (count = 0; count < 32; count++)
                map[count] = 0;

        /* Set bits in delimiter table */
        do
        {
            map[*ctrl >> 3] |= (1 << (*ctrl & 7));
        } while (*ctrl++);

        /* Initialize str. */
        str = *pstring;

        /* Find beginning of token (skip over leading delimiters). Note that
         * there is no token if this loop sets str to point to the terminal
         * null (*str == '\0') */
        while ( (map[*str >> 3] & (1 << (*str & 7))) && *str )
            str++;

        tokenstr = str;

        /* Find the end of the token. If it is not the end of the string,
         * put a null there. */
        for ( ; *str ; str++ )
        {
            if ( map[*str >> 3] & (1 << (*str & 7)) )
            {
                *str++ = '\0';
                break;
            }
        }

        /* string now points to beginning of next token */
        *pstring = str;

        /* Determine if a token has been found. */
        if ( tokenstr == str )
            return NULL;
        else
            return tokenstr;
}