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