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package humanize
/*
Slightly adapted from the source to fit go-humanize.
Author: https://github.com/gorhill
Source: https://gist.github.com/gorhill/5285193
*/
import (
"math"
"strconv"
)
var (
renderFloatPrecisionMultipliers = [...]float64{
1,
10,
100,
1000,
10000,
100000,
1000000,
10000000,
100000000,
1000000000,
}
renderFloatPrecisionRounders = [...]float64{
0.5,
0.05,
0.005,
0.0005,
0.00005,
0.000005,
0.0000005,
0.00000005,
0.000000005,
0.0000000005,
}
)
// FormatFloat produces a formatted number as string based on the following user-specified criteria:
// * thousands separator
// * decimal separator
// * decimal precision
//
// Usage: s := RenderFloat(format, n)
// The format parameter tells how to render the number n.
//
// See examples: http://play.golang.org/p/LXc1Ddm1lJ
//
// Examples of format strings, given n = 12345.6789:
// "#,###.##" => "12,345.67"
// "#,###." => "12,345"
// "#,###" => "12345,678"
// "#\u202F###,##" => "12 345,68"
// "#.###,###### => 12.345,678900
// "" (aka default format) => 12,345.67
//
// The highest precision allowed is 9 digits after the decimal symbol.
// There is also a version for integer number, FormatInteger(),
// which is convenient for calls within template.
func FormatFloat(format string, n float64) string {
// Special cases:
// NaN = "NaN"
// +Inf = "+Infinity"
// -Inf = "-Infinity"
if math.IsNaN(n) {
return "NaN"
}
if n > math.MaxFloat64 {
return "Infinity"
}
if n < -math.MaxFloat64 {
return "-Infinity"
}
// default format
precision := 2
decimalStr := "."
thousandStr := ","
positiveStr := ""
negativeStr := "-"
if len(format) > 0 {
format := []rune(format)
// If there is an explicit format directive,
// then default values are these:
precision = 9
thousandStr = ""
// collect indices of meaningful formatting directives
formatIndx := []int{}
for i, char := range format {
if char != '#' && char != '0' {
formatIndx = append(formatIndx, i)
}
}
if len(formatIndx) > 0 {
// Directive at index 0:
// Must be a '+'
// Raise an error if not the case
// index: 0123456789
// +0.000,000
// +000,000.0
// +0000.00
// +0000
if formatIndx[0] == 0 {
if format[formatIndx[0]] != '+' {
panic("RenderFloat(): invalid positive sign directive")
}
positiveStr = "+"
formatIndx = formatIndx[1:]
}
// Two directives:
// First is thousands separator
// Raise an error if not followed by 3-digit
// 0123456789
// 0.000,000
// 000,000.00
if len(formatIndx) == 2 {
if (formatIndx[1] - formatIndx[0]) != 4 {
panic("RenderFloat(): thousands separator directive must be followed by 3 digit-specifiers")
}
thousandStr = string(format[formatIndx[0]])
formatIndx = formatIndx[1:]
}
// One directive:
// Directive is decimal separator
// The number of digit-specifier following the separator indicates wanted precision
// 0123456789
// 0.00
// 000,0000
if len(formatIndx) == 1 {
decimalStr = string(format[formatIndx[0]])
precision = len(format) - formatIndx[0] - 1
}
}
}
// generate sign part
var signStr string
if n >= 0.000000001 {
signStr = positiveStr
} else if n <= -0.000000001 {
signStr = negativeStr
n = -n
} else {
signStr = ""
n = 0.0
}
// split number into integer and fractional parts
intf, fracf := math.Modf(n + renderFloatPrecisionRounders[precision])
// generate integer part string
intStr := strconv.FormatInt(int64(intf), 10)
// add thousand separator if required
if len(thousandStr) > 0 {
for i := len(intStr); i > 3; {
i -= 3
intStr = intStr[:i] + thousandStr + intStr[i:]
}
}
// no fractional part, we can leave now
if precision == 0 {
return signStr + intStr
}
// generate fractional part
fracStr := strconv.Itoa(int(fracf * renderFloatPrecisionMultipliers[precision]))
// may need padding
if len(fracStr) < precision {
fracStr = "000000000000000"[:precision-len(fracStr)] + fracStr
}
return signStr + intStr + decimalStr + fracStr
}
// FormatInteger produces a formatted number as string.
// See FormatFloat.
func FormatInteger(format string, n int) string {
return FormatFloat(format, float64(n))
}
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