40 lines
829 B
Go
40 lines
829 B
Go
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package types
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import (
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"fmt"
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"math"
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"strconv"
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"golang.org/x/xerrors"
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)
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// Percent stores a signed percentage as an int64. When converted to a string (or json), it's stored
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// as a decimal with two places (e.g., 100% -> 1.00).
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type Percent int64
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func (p Percent) String() string {
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abs := p
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sign := ""
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if abs < 0 {
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abs = -abs
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sign = "-"
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}
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return fmt.Sprintf(`%s%d.%d`, sign, abs/100, abs%100)
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}
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func (p Percent) MarshalJSON() ([]byte, error) {
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return []byte(p.String()), nil
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}
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func (p *Percent) UnmarshalJSON(b []byte) error {
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flt, err := strconv.ParseFloat(string(b)+"e2", 64)
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if err != nil {
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return xerrors.Errorf("unable to parse ratio %s: %w", string(b), err)
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}
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if math.Trunc(flt) != flt {
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return xerrors.Errorf("ratio may only have two decimals: %s", string(b))
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}
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*p = Percent(flt)
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return nil
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}
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