David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame] | 1 | package units |
| 2 | |
| 3 | import ( |
| 4 | "fmt" |
| 5 | "regexp" |
| 6 | "strconv" |
| 7 | "strings" |
| 8 | ) |
| 9 | |
| 10 | // See: http://en.wikipedia.org/wiki/Binary_prefix |
| 11 | const ( |
| 12 | // Decimal |
| 13 | |
| 14 | KB = 1000 |
| 15 | MB = 1000 * KB |
| 16 | GB = 1000 * MB |
| 17 | TB = 1000 * GB |
| 18 | PB = 1000 * TB |
| 19 | |
| 20 | // Binary |
| 21 | |
| 22 | KiB = 1024 |
| 23 | MiB = 1024 * KiB |
| 24 | GiB = 1024 * MiB |
| 25 | TiB = 1024 * GiB |
| 26 | PiB = 1024 * TiB |
| 27 | ) |
| 28 | |
| 29 | type unitMap map[string]int64 |
| 30 | |
| 31 | var ( |
| 32 | decimalMap = unitMap{"k": KB, "m": MB, "g": GB, "t": TB, "p": PB} |
| 33 | binaryMap = unitMap{"k": KiB, "m": MiB, "g": GiB, "t": TiB, "p": PiB} |
| 34 | sizeRegex = regexp.MustCompile(`^(\d+(\.\d+)*) ?([kKmMgGtTpP])?[bB]?$`) |
| 35 | ) |
| 36 | |
| 37 | var decimapAbbrs = []string{"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"} |
| 38 | var binaryAbbrs = []string{"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"} |
| 39 | |
| 40 | func getSizeAndUnit(size float64, base float64, _map []string) (float64, string) { |
| 41 | i := 0 |
| 42 | unitsLimit := len(_map) - 1 |
| 43 | for size >= base && i < unitsLimit { |
| 44 | size = size / base |
| 45 | i++ |
| 46 | } |
| 47 | return size, _map[i] |
| 48 | } |
| 49 | |
| 50 | // CustomSize returns a human-readable approximation of a size |
| 51 | // using custom format. |
| 52 | func CustomSize(format string, size float64, base float64, _map []string) string { |
| 53 | size, unit := getSizeAndUnit(size, base, _map) |
| 54 | return fmt.Sprintf(format, size, unit) |
| 55 | } |
| 56 | |
| 57 | // HumanSizeWithPrecision allows the size to be in any precision, |
| 58 | // instead of 4 digit precision used in units.HumanSize. |
| 59 | func HumanSizeWithPrecision(size float64, precision int) string { |
| 60 | size, unit := getSizeAndUnit(size, 1000.0, decimapAbbrs) |
| 61 | return fmt.Sprintf("%.*g%s", precision, size, unit) |
| 62 | } |
| 63 | |
| 64 | // HumanSize returns a human-readable approximation of a size |
| 65 | // capped at 4 valid numbers (eg. "2.746 MB", "796 KB"). |
| 66 | func HumanSize(size float64) string { |
| 67 | return HumanSizeWithPrecision(size, 4) |
| 68 | } |
| 69 | |
| 70 | // BytesSize returns a human-readable size in bytes, kibibytes, |
| 71 | // mebibytes, gibibytes, or tebibytes (eg. "44kiB", "17MiB"). |
| 72 | func BytesSize(size float64) string { |
| 73 | return CustomSize("%.4g%s", size, 1024.0, binaryAbbrs) |
| 74 | } |
| 75 | |
| 76 | // FromHumanSize returns an integer from a human-readable specification of a |
| 77 | // size using SI standard (eg. "44kB", "17MB"). |
| 78 | func FromHumanSize(size string) (int64, error) { |
| 79 | return parseSize(size, decimalMap) |
| 80 | } |
| 81 | |
| 82 | // RAMInBytes parses a human-readable string representing an amount of RAM |
| 83 | // in bytes, kibibytes, mebibytes, gibibytes, or tebibytes and |
| 84 | // returns the number of bytes, or -1 if the string is unparseable. |
| 85 | // Units are case-insensitive, and the 'b' suffix is optional. |
| 86 | func RAMInBytes(size string) (int64, error) { |
| 87 | return parseSize(size, binaryMap) |
| 88 | } |
| 89 | |
| 90 | // Parses the human-readable size string into the amount it represents. |
| 91 | func parseSize(sizeStr string, uMap unitMap) (int64, error) { |
| 92 | matches := sizeRegex.FindStringSubmatch(sizeStr) |
| 93 | if len(matches) != 4 { |
| 94 | return -1, fmt.Errorf("invalid size: '%s'", sizeStr) |
| 95 | } |
| 96 | |
| 97 | size, err := strconv.ParseFloat(matches[1], 64) |
| 98 | if err != nil { |
| 99 | return -1, err |
| 100 | } |
| 101 | |
| 102 | unitPrefix := strings.ToLower(matches[3]) |
| 103 | if mul, ok := uMap[unitPrefix]; ok { |
| 104 | size *= float64(mul) |
| 105 | } |
| 106 | |
| 107 | return int64(size), nil |
| 108 | } |