/**********
Copyright 1990 Regents of the University of California.  All rights reserved.
Author: 1985 Wayne A. Christopher, U. C. Berkeley CAD Group
**********/

/*
 * Do backquote substitution on a word list.
 */

#include "ngspice/ngspice.h"
#include "ngspice/cpdefs.h"
#include "backq.h"


static wordlist *backeval(char *string);

char cp_back = '`';


wordlist *
cp_bquote(wordlist *wlist)
{
    wordlist *wl, *nwl;
    char *s, *t, buf[BSIZE_SP], wbuf[BSIZE_SP], tbuf[BSIZE_SP];
    int i;

    for (wl = wlist; wl; wl = wl->wl_next) {

        t = wl->wl_word;
        if (!t)
            continue;
        i = 0;
    loop:
        s = strchr(t, cp_back);
        if (s == NULL)
            continue;
        while (t < s)
            wbuf[i++] = *t++;
        wbuf[i] = '\0';
        t++;
        s = buf;
        /* Get s and t past the next backquote. */
        while (*t && (*t != cp_back))
            *s++ = *t++;
        /* What the heck, let "echo `foo" work... */
        *s = '\0';
        if (*t != '\0')
            t++;    /* Get past the second ` */
        if ((nwl = backeval(buf)) == NULL) {
            wlist->wl_word = NULL;
            return (wlist);
        }
        (void) strcpy(buf, wbuf);
        if (nwl->wl_word) {
            (void) strcat(buf, nwl->wl_word);
            tfree(nwl->wl_word);
        }
        nwl->wl_word = copy(buf);

        (void) strcpy(tbuf, t);
        wl = wl_splice(wl, nwl);
        for (wlist = wl; wlist->wl_prev; wlist = wlist->wl_prev)
            ;
        /* MW. We must move to the begging of new wordlist. */

        (void) strcpy(buf, wl->wl_word);
        i = (int) strlen(buf);
        (void) strcat(buf, tbuf);
        tfree(wl->wl_word);
        wl->wl_word = copy(buf);
        t = &wl->wl_word[i];
        s = wl->wl_word;
        for (i = 0; s < t; s++)
            wbuf[i++] = *s;
        goto loop;
    }
    return (wlist);
}


/* Do a popen with the string, and then reset the file pointers so that
 * we can use the first pass of the parser on the output.
 */

static wordlist *
backeval(char *string)
{
#ifdef HAVE_POPEN
    FILE *proc, *old;
    wordlist *wl;
    bool intv;

    proc = popen(string, "r");
    if (proc == NULL) {
        fprintf(cp_err, "Error: can't evaluate %s.\n", string);
        return (NULL);
    }
    old = cp_inp_cur;
    cp_inp_cur = proc;
    intv = cp_interactive;
    cp_interactive = FALSE;
    cp_bqflag = TRUE;
    wl = cp_lexer(NULL);
    cp_bqflag = FALSE;
    cp_inp_cur = old;
    cp_interactive = intv;
    (void) pclose(proc);
    return (wl);
#else
    wordlist *wl = wl_cons(copy(string), NULL);
    return (wl);
#endif
}