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- package encoding
- import (
- "fmt"
- "math"
- "strconv"
- )
- // EncodeFloat encodes a float value as per the stdlib encoder for json and xml protocol
- // This encodes a float value into dst while attempting to conform to ES6 ToString for Numbers
- //
- // Based on encoding/json floatEncoder from the Go Standard Library
- // https://golang.org/src/encoding/json/encode.go
- func EncodeFloat(dst []byte, v float64, bits int) []byte {
- if math.IsInf(v, 0) || math.IsNaN(v) {
- panic(fmt.Sprintf("invalid float value: %s", strconv.FormatFloat(v, 'g', -1, bits)))
- }
- abs := math.Abs(v)
- fmt := byte('f')
- if abs != 0 {
- if bits == 64 && (abs < 1e-6 || abs >= 1e21) || bits == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
- fmt = 'e'
- }
- }
- dst = strconv.AppendFloat(dst, v, fmt, -1, bits)
- if fmt == 'e' {
- // clean up e-09 to e-9
- n := len(dst)
- if n >= 4 && dst[n-4] == 'e' && dst[n-3] == '-' && dst[n-2] == '0' {
- dst[n-2] = dst[n-1]
- dst = dst[:n-1]
- }
- }
- return dst
- }
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