str.chomp!(separator=$/)   → str or nil

Modifies str in place as described for String#chomp, returning str, or nil if no modifications were made.

Source Code

/*
*  call-seq:
*     str.chomp!(separator=$/)   => str or nil
*  
*  Modifies <i>str</i> in place as described for <code>String#chomp</code>,
*  returning <i>str</i>, or <code>nil</code> if no modifications were made.
*/

static VALUE
rb_str_chomp_bang(argc, argv, str)
   int argc;
   VALUE *argv;
   VALUE str;
{
   VALUE rs;
   int newline;
   char *p;
   long len, rslen;

   if (rb_scan_args(argc, argv, "01", &rs) == 0) {
       len = RSTRING(str)->len;
       if (len == 0) return Qnil;
       p = RSTRING(str)->ptr;
       rs = rb_rs;
       if (rs == rb_default_rs) {
         smart_chomp:
           rb_str_modify(str);
           if (RSTRING(str)->ptr[len-1] == '\n') {
               RSTRING(str)->len--;
               if (RSTRING(str)->len > 0 &&
                   RSTRING(str)->ptr[RSTRING(str)->len-1] == '\r') {
                   RSTRING(str)->len--;
               }
           }
           else if (RSTRING(str)->ptr[len-1] == '\r') {
               RSTRING(str)->len--;
           }
           else {
               return Qnil;
           }
           RSTRING(str)->ptr[RSTRING(str)->len] = '\0';
           return str;
       }
   }
   if (NIL_P(rs)) return Qnil;
   StringValue(rs);
   len = RSTRING(str)->len;
   if (len == 0) return Qnil;
   p = RSTRING(str)->ptr;
   rslen = RSTRING(rs)->len;
   if (rslen == 0) {
       while (len>0 && p[len-1] == '\n') {
           len--;
           if (len>0 && p[len-1] == '\r')
               len--;
       }
       if (len < RSTRING(str)->len) {
           rb_str_modify(str);
           RSTRING(str)->len = len;
           RSTRING(str)->ptr[len] = '\0';
           return str;
       }
       return Qnil;
   }
   if (rslen > len) return Qnil;
   newline = RSTRING(rs)->ptr[rslen-1];
   if (rslen == 1 && newline == '\n')
       goto smart_chomp;

   if (p[len-1] == newline &&
       (rslen <= 1 ||
        rb_memcmp(RSTRING(rs)->ptr, p+len-rslen, rslen) == 0)) {
       rb_str_modify(str);
       RSTRING(str)->len -= rslen;
       RSTRING(str)->ptr[RSTRING(str)->len] = '\0';
       return str;
   }
   return Qnil;
}