Reimplement with_{scale,prec} to use default rounding

src/lib.rs

@@ -268,27 +268,12 @@ impl BigDecimal {
  /// Return a new BigDecimal object equivalent to self, with internal
  /// scaling set to the number specified.
  /// If the new_scale is lower than the current value (indicating a larger
- /// power of 10), digits will be dropped (as precision is lower)
+ /// power of 10), digits will be rounded (as precision is lower)
  ///
  #[inline]
  pub fn with_scale(&self, new_scale: i64) -> BigDecimal {
- if self.int_val.is_zero() {
- return BigDecimal::new(BigInt::zero(), new_scale);
- }
-
- match new_scale.cmp(&self.scale) {
- Ordering::Greater => {
- let scale_diff = new_scale - self.scale;
- let int_val = &self.int_val * ten_to_the(scale_diff as u64);
- BigDecimal::new(int_val, new_scale)
- }
- Ordering::Less => {
- let scale_diff = self.scale - new_scale;
- let int_val = &self.int_val / ten_to_the(scale_diff as u64);
- BigDecimal::new(int_val, new_scale)
- }
- Ordering::Equal => self.clone(),
- }
+ let mode = Context::default().rounding_mode();
+ self.with_scale_round(new_scale, mode)
  }
 
  /// Return a new BigDecimal after shortening the digits and rounding
@@ -446,32 +431,12 @@ impl BigDecimal {
  /// assert_eq!(scale, 9);
  /// ```
  pub fn with_prec(&self, prec: u64) -> BigDecimal {
- let digits = self.digits();
-
- match digits.cmp(&prec) {
- Ordering::Greater => {
- let diff = digits - prec;
- let p = ten_to_the(diff);
- let (mut q, r) = self.int_val.div_rem(&p);
-
- // check for "leading zero" in remainder term; otherwise round
- if p < 10 * &r {
- q += get_rounding_term(&r);
- }
-
- BigDecimal {
- int_val: q,
- scale: self.scale - diff as i64,
- }
- }
- Ordering::Less => {
- let diff = prec - digits;
- BigDecimal {
- int_val: &self.int_val * ten_to_the(diff),
- scale: self.scale + diff as i64,
- }
+ match stdlib::num::NonZeroU64::new(prec) {
+ None => BigDecimal::zero(),
+ Some(prec) => {
+ let mode = Context::default().rounding_mode();
+ self.with_precision_round(prec, mode)
  }
- Ordering::Equal => self.clone(),
  }
  }