lexan.c File Reference

#include <xinu.h>

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Functions
int32	lexan (char *line, int32 len, char *tokbuf, int32 *tlen, int32 tok[], int32 toktyp[])

Function Documentation

lexan()

int32 lexan	(	char *	line,
		int32	len,
		char *	tokbuf,
		int32 *	tlen,
		int32	tok[],
		int32	toktyp[]
	)

Definition at line 10 of file lexan.c.

References NULLCH, SH_AMPER, SH_BLANK, SH_DQUOTE, SH_GREATER, SH_LESS, SH_NEWLINE, SH_SQUOTE, SH_TAB, SH_TOK_AMPER, SH_TOK_GREATER, SH_TOK_LESS, SH_TOK_OTHER, SHELL_MAXTOK, and SYSERR.

Referenced by shell().

{
    char    quote;          /* Character for quoted string  */
    uint32  ntok;           /* Number of tokens found   */
    char    *p;         /* Pointer that walks along the */
                    /*   input line         */
    int32   tbindex;        /* Index into tokbuf        */
    char    ch;         /* Next char from input line    */

    /* Start at the beginning of the line with no tokens */

    ntok = 0;
    p = line;
    tbindex = 0;

    /* While not yet at end of line, get next token */

    while ( (*p != NULLCH) && (*p != SH_NEWLINE) ) {

        /* If too many tokens, return error */

        if (ntok >= SHELL_MAXTOK) {
            return SYSERR;
        }

        /* Skip whitespace before token */

        while ( (*p == SH_BLANK) || (*p == SH_TAB) ) {
            p++;
        }

        /* Stop parsing at end of line (or end of string) */

        ch = *p;
        if ( (ch==SH_NEWLINE) || (ch==NULLCH) ) {
            *tlen = tbindex;
            return ntok;
        }

        /* Set next entry in tok array to be an index to the    */
        /*   current location in the token buffer       */

        tok[ntok] = tbindex;    /* the start of the token   */

        /* Set the token type */

        switch (ch) {

            case SH_AMPER:  toktyp[ntok] = SH_TOK_AMPER;
                    tokbuf[tbindex++] = ch;
                    tokbuf[tbindex++] = NULLCH;
                    ntok++;
                    p++;
                    continue;

            case SH_LESS:   toktyp[ntok] = SH_TOK_LESS;
                    tokbuf[tbindex++] = ch;
                    tokbuf[tbindex++] = NULLCH;
                    ntok++;
                    p++;
                    continue;

            case SH_GREATER:    toktyp[ntok] = SH_TOK_GREATER;
                    tokbuf[tbindex++] = ch;
                    tokbuf[tbindex++] = NULLCH;
                    ntok++;
                    p++;
                    continue;

            default:        toktyp[ntok] = SH_TOK_OTHER;
        };

        /* Handle quoted string (single or double quote) */

        if ( (ch==SH_SQUOTE) || (ch==SH_DQUOTE) ) {
            quote = ch; /* remember opening quote */

            /* Copy quoted string to arg area */

            p++;    /* Move past starting quote */

            while ( ((ch=*p++) != quote) && (ch != SH_NEWLINE)
                    && (ch != NULLCH) ) {
                tokbuf[tbindex++] = ch;
            }
            if (ch != quote) {  /* string missing end quote */
                return SYSERR;
            }

            /* Finished string - count token and go on  */

            tokbuf[tbindex++] = NULLCH; /* terminate token  */
            ntok++;     /* count string as one token    */
            continue;   /* go to next token     */
        }

        /* Handle a token other than a quoted string        */

        tokbuf[tbindex++] = ch; /* put first character in buffer*/
        p++;

        while ( ((ch = *p) != SH_NEWLINE) && (ch != NULLCH)
            && (ch != SH_LESS)  && (ch != SH_GREATER)
            && (ch != SH_BLANK) && (ch != SH_TAB)
            && (ch != SH_AMPER) && (ch != SH_SQUOTE)
            && (ch != SH_DQUOTE) )  {
                tokbuf[tbindex++] = ch;
                p++;
        }

        /* Report error if other token is appended */

        if (       (ch == SH_SQUOTE) || (ch == SH_DQUOTE)
            || (ch == SH_LESS)   || (ch == SH_GREATER) ) {
            return SYSERR;
        }

        tokbuf[tbindex++] = NULLCH; /* terminate the token  */

                ntok++;             /* count valid token    */

    }
    *tlen = tbindex;
    return ntok;
}

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