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125 lines
2.3 KiB
Go
125 lines
2.3 KiB
Go
/*
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Simple byte size formatting.
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This package implements types that can be used in stdlib formatting functions
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like `fmt.Printf` to control the output of the expected printed string.
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Floating point flags %f and %g print the value in using the correct unit
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suffix. Decimal units are default, # switches to binary units. If a value is
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best represented as full bytes, integer bytes are printed instead.
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Examples:
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fmt.Printf("%.2f", 123 * B) => "123B"
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fmt.Printf("%.2f", 1234 * B) => "1.23kB"
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fmt.Printf("%g", 1200 * B) => "1.2kB"
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fmt.Printf("%#g", 1024 * B) => "1KiB"
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Integer flag %d always prints the value in bytes. # flag adds an unit prefix.
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Examples:
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fmt.Printf("%d", 1234 * B) => "1234"
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fmt.Printf("%#d", 1234 * B) => "1234B"
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%v is equal to %g
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*/
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package units
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import (
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"fmt"
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"io"
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"math"
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"math/big"
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)
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type Bytes int64
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const (
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B Bytes = 1 << (10 * iota)
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KiB
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MiB
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GiB
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TiB
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PiB
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EiB
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KB = 1e3 * B
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MB = 1e3 * KB
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GB = 1e3 * MB
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TB = 1e3 * GB
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PB = 1e3 * TB
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EB = 1e3 * PB
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)
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var units = map[bool][]string{
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false: []string{
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"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB",
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},
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true: []string{
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"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB",
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},
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}
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func (b Bytes) Format(f fmt.State, c rune) {
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switch c {
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case 'f', 'g':
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fv, unit, ok := b.floatValue(f.Flag('#'))
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if !ok {
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b.formatInt(&noPrecision{f}, 'd', true)
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return
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}
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big.NewFloat(fv).Format(f, c)
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io.WriteString(f, unit)
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case 'd':
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b.formatInt(f, c, f.Flag('#'))
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default:
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if f.Flag('#') {
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fmt.Fprintf(f, "bytes(%d)", int64(b))
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} else {
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fmt.Fprintf(f, "%g", b)
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}
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}
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}
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func (b Bytes) formatInt(f fmt.State, c rune, withUnit bool) {
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big.NewInt(int64(b)).Format(f, c)
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if withUnit {
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io.WriteString(f, "B")
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}
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}
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func (b Bytes) floatValue(binary bool) (float64, string, bool) {
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i := 0
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var baseUnit Bytes = 1
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if b < 0 {
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baseUnit *= -1
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}
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for {
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next := baseUnit
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if binary {
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next *= 1 << 10
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} else {
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next *= 1e3
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}
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if (baseUnit > 0 && b >= next) || (baseUnit < 0 && b <= next) {
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i++
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baseUnit = next
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continue
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}
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if i == 0 {
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return 0, "", false
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}
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return float64(b) / math.Abs(float64(baseUnit)), units[binary][i], true
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}
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}
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type noPrecision struct {
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fmt.State
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}
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func (*noPrecision) Precision() (prec int, ok bool) {
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return 0, false
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}
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