internal/number: factor out code
for implementers of Convert (down the line)
removed scale and precision while at it
Change-Id: I0a7ef49d63e7042cd8b3602d56dd3cc472ad328b
Reviewed-on: https://go-review.googlesource.com/60710
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
diff --git a/internal/number/decimal.go b/internal/number/decimal.go
index 221a8b1..ac2098d 100644
--- a/internal/number/decimal.go
+++ b/internal/number/decimal.go
@@ -412,21 +412,11 @@
// Something like this would work:
// AppendDigits(dst []byte, x float64, base, size, prec int) (digits []byte, exp, accuracy int)
if r.Mode == ToNearestEven {
- // We can't round if limitations are placed on both the fraction and
- // significant digits.
- if r.MaxFractionDigits == 0 && r.MaxSignificantDigits > 0 {
- prec = int(r.MaxSignificantDigits)
- } else if r.isScientific() {
- if r.MaxIntegerDigits == 1 && (r.MaxSignificantDigits == 0 ||
- int(r.MaxFractionDigits+1) == int(r.MaxSignificantDigits)) {
- verb = 'e'
- // Note: don't add DigitShift: it is only used for decimals.
- prec = int(r.MaxFractionDigits)
- prec += int(r.DigitShift)
- }
- } else if r.MaxFractionDigits > 0 && r.MaxSignificantDigits == 0 {
+ if n := r.RoundSignificantDigits(); n >= 0 {
+ prec = n
+ } else if n = r.RoundFractionDigits(); n >= 0 {
+ prec = n
verb = 'f'
- prec = int(r.MaxFractionDigits) + int(r.DigitShift)
}
}
diff --git a/internal/number/pattern.go b/internal/number/pattern.go
index 2764cd2..eebaafd 100644
--- a/internal/number/pattern.go
+++ b/internal/number/pattern.go
@@ -77,15 +77,33 @@
MinExponentDigits uint8
}
-func (r *RoundingContext) scale() int {
- // scale is 0 when precision is set.
- if r.MaxSignificantDigits != 0 {
- return 0
+// RoundSignificantDigits returns the number of significant digits an
+// implementation of Convert may round to or n < 0 if there is no maximum or
+// a maximum is not recommended.
+func (r *RoundingContext) RoundSignificantDigits() (n int) {
+ if r.MaxFractionDigits == 0 && r.MaxSignificantDigits > 0 {
+ return int(r.MaxSignificantDigits)
+ } else if r.isScientific() && r.MaxIntegerDigits == 1 {
+ if r.MaxSignificantDigits == 0 ||
+ int(r.MaxFractionDigits+1) == int(r.MaxSignificantDigits) {
+ // Note: don't add DigitShift: it is only used for decimals.
+ return int(r.MaxFractionDigits) + 1
+ }
}
- return int(r.MaxFractionDigits)
+ return -1
}
-func (r *RoundingContext) precision() int { return int(r.MaxSignificantDigits) }
+// RoundFractionDigits returns the number of fraction digits an implementation
+// of Convert may round to or n < 0 if there is no maximum or a maximum is not
+// recommended.
+func (r *RoundingContext) RoundFractionDigits() (n int) {
+ if r.MinExponentDigits == 0 &&
+ r.MaxSignificantDigits == 0 &&
+ r.MaxFractionDigits >= 0 {
+ return int(r.MaxFractionDigits) + int(r.DigitShift)
+ }
+ return -1
+}
// SetScale fixes the RoundingContext to a fixed number of fraction digits.
func (r *RoundingContext) SetScale(scale int) {
