gistfile1.c

static VALUE
rb_str_each_line(argc, argv, str)
    int argc;
    VALUE *argv;
    VALUE str;
{
    VALUE rs;
    int newline;
    char *p = RSTRING(str)->ptr, *pend = p + RSTRING(str)->len, *s;
    char *ptr = p;
    long len = RSTRING(str)->len, rslen;
    VALUE line;

    if (rb_scan_args(argc, argv, "01", &rs) == 0) {
    rs = rb_rs;
    }
    RETURN_ENUMERATOR(str, argc, argv);
    if (NIL_P(rs)) {
    rb_yield(str);
    return str;
    }
    StringValue(rs);
    rslen = RSTRING(rs)->len;
    if (rslen == 0) {
    newline = '\n';
    }
    else {
    newline = RSTRING(rs)->ptr[rslen-1];
    }

    for (s = p, p += rslen; p < pend; p++) {
    if (rslen == 0 && *p == '\n') {
        if (*++p != '\n') continue;
        while (*p == '\n') p++;
    }
    if (RSTRING(str)->ptr < p && p[-1] == newline &&
        (rslen <= 1 ||
         rb_memcmp(RSTRING(rs)->ptr, p-rslen, rslen) == 0)) {
        line = rb_str_new5(str, s, p - s);
        OBJ_INFECT(line, str);
        rb_yield(line);
        str_mod_check(str, ptr, len);
        s = p;
    }
    }

    if (s != pend) {
    if (p > pend) p = pend;
    line = rb_str_new5(str, s, p - s);
    OBJ_INFECT(line, str);
    rb_yield(line);
    }

    return str;
}