93 lines
1.9 KiB
Go
93 lines
1.9 KiB
Go
package util
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import (
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"bytes"
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"encoding/json"
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"errors"
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"strconv"
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"strings"
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)
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const (
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precision = 8
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decimals = 100000000
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)
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var errInvalidString = errors.New("Fixed8 must satisfy following regex \\d+(\\.\\d{1,8})?")
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// Fixed8 represents a fixed-point number with precision 10^-8.
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type Fixed8 int64
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// String implements the Stringer interface.
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func (f Fixed8) String() string {
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buf := new(bytes.Buffer)
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val := int64(f)
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if val < 0 {
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buf.WriteRune('-')
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val = -val
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}
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str := strconv.FormatInt(val/decimals, 10)
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buf.WriteString(str)
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val %= decimals
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if val > 0 {
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buf.WriteRune('.')
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str = strconv.FormatInt(val, 10)
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for i := len(str); i < 8; i++ {
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buf.WriteRune('0')
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}
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buf.WriteString(str)
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}
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return buf.String()
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}
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// Value returns the original value representing the Fixed8.
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func (f Fixed8) Value() int64 {
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return int64(f) / int64(decimals)
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}
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// NewFixed8 return a new Fixed8 type multiplied by decimals.
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func NewFixed8(val int) Fixed8 {
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return Fixed8(decimals * val)
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}
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// Fixed8DecodeString parses s which must be a fixed point number
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// with precision up to 10^-8
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func Fixed8DecodeString(s string) (Fixed8, error) {
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parts := strings.SplitN(s, ".", 2)
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ip, err := strconv.Atoi(parts[0])
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if err != nil {
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return 0, errInvalidString
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} else if len(parts) == 1 {
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return NewFixed8(ip), nil
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}
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fp, err := strconv.Atoi(parts[1])
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if err != nil || fp >= decimals {
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return 0, errInvalidString
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}
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for i := len(parts[1]); i < precision; i++ {
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fp *= 10
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}
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return Fixed8(ip*decimals + fp), nil
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}
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// UnmarshalJSON implements the json unmarshaller interface.
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func (f *Fixed8) UnmarshalJSON(data []byte) error {
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var s string
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if err := json.Unmarshal(data, &s); err == nil {
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p, err := Fixed8DecodeString(s)
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if err != nil {
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return err
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}
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*f = p
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return nil
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}
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var fl float64
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if err := json.Unmarshal(data, &fl); err != nil {
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return err
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}
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*f = Fixed8(decimals * fl)
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return nil
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}
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