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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package number
import (
"strconv"
"golang.org/x/text/language"
)
// TODO:
// - public (but internal) API for creating formatters
// - split out the logic that computes the visible digits from the rest of the
// formatting code (needed for plural).
// - grouping of fractions
// - reuse percent pattern for permille
// - padding
// Formatter contains all the information needed to render a number.
type Formatter struct {
*Pattern
Info
RoundingContext
f func(dst []byte, f *Formatter, d *Decimal) []byte
}
func lookupFormat(t language.Tag, tagToIndex []uint8) *Pattern {
for ; ; t = t.Parent() {
if ci, ok := language.CompactIndex(t); ok {
return &formats[tagToIndex[ci]]
}
}
}
func (f *Formatter) Format(dst []byte, d *Decimal) []byte {
return f.f(dst, f, d)
}
func appendDecimal(dst []byte, f *Formatter, d *Decimal) []byte {
if dst, ok := f.renderSpecial(dst, d); ok {
return dst
}
n := d.normalize()
if maxSig := int(f.MaxSignificantDigits); maxSig > 0 {
n.round(ToZero, maxSig)
}
digits := n.Digits
exp := n.Exp
// Split in integer and fraction part.
var intDigits, fracDigits []byte
var numInt, numFrac int
if exp > 0 {
numInt = int(exp)
if int(exp) >= len(digits) { // ddddd | ddddd00
intDigits = digits
} else { // ddd.dd
intDigits = digits[:exp]
fracDigits = digits[exp:]
numFrac = len(fracDigits)
}
} else {
fracDigits = digits
numFrac = -int(exp) + len(digits)
}
// Cap integer digits. Remove *most-significant* digits.
if f.MaxIntegerDigits > 0 && numInt > int(f.MaxIntegerDigits) {
offset := numInt - int(f.MaxIntegerDigits)
if offset > len(intDigits) {
numInt = 0
intDigits = nil
} else {
numInt = int(f.MaxIntegerDigits)
intDigits = intDigits[offset:]
// for keeping track of significant digits
digits = digits[offset:]
}
// Strip leading zeros. Resulting number of digits is significant digits.
for len(intDigits) > 0 && intDigits[0] == 0 {
intDigits = intDigits[1:]
digits = digits[1:]
numInt--
}
}
if f.MaxSignificantDigits == 0 && int(f.MaxFractionDigits) < numFrac {
if extra := numFrac - int(f.MaxFractionDigits); extra > len(fracDigits) {
numFrac = 0
fracDigits = nil
} else {
numFrac = int(f.MaxFractionDigits)
fracDigits = fracDigits[:len(fracDigits)-extra]
}
}
neg := d.Neg && numInt+numFrac > 0
affix, suffix := f.getAffixes(neg)
dst = appendAffix(dst, f, affix, neg)
savedLen := len(dst)
minInt := int(f.MinIntegerDigits)
if minInt == 0 && f.MinSignificantDigits > 0 {
minInt = 1
}
// add leading zeros
for i := numInt; i < minInt; i++ {
dst = f.AppendDigit(dst, 0)
if f.needsSep(minInt - i) {
dst = append(dst, f.Symbol(SymGroup)...)
}
}
i := 0
for ; i < len(intDigits); i++ {
dst = f.AppendDigit(dst, intDigits[i])
if f.needsSep(numInt - i) {
dst = append(dst, f.Symbol(SymGroup)...)
}
}
for ; i < numInt; i++ {
dst = f.AppendDigit(dst, 0)
if f.needsSep(numInt - i) {
dst = append(dst, f.Symbol(SymGroup)...)
}
}
trailZero := int(f.MinFractionDigits) - numFrac
if d := int(f.MinSignificantDigits) - len(digits); d > 0 && d > trailZero {
trailZero = d
}
if numFrac > 0 || trailZero > 0 || f.Flags&AlwaysDecimalSeparator != 0 {
dst = append(dst, f.Symbol(SymDecimal)...)
}
// Add leading zeros
for i := numFrac - len(fracDigits); i > 0; i-- {
dst = f.AppendDigit(dst, 0)
}
i = 0
for ; i < len(fracDigits); i++ {
dst = f.AppendDigit(dst, fracDigits[i])
}
for ; trailZero > 0; trailZero-- {
dst = f.AppendDigit(dst, 0)
}
// Ensure that at least one digit is written no matter what. This makes
// things more robust, even though a pattern should always require at least
// one fraction or integer digit.
if len(dst) == savedLen {
dst = f.AppendDigit(dst, 0)
}
return appendAffix(dst, f, suffix, neg)
}
func appendScientific(dst []byte, f *Formatter, d *Decimal) []byte {
if dst, ok := f.renderSpecial(dst, d); ok {
return dst
}
// Significant digits are transformed by parser for scientific notation and
// do not need to be handled here.
maxInt, numInt := int(f.MaxIntegerDigits), int(f.MinIntegerDigits)
if numInt == 0 {
numInt = 1
}
maxSig := int(f.MaxFractionDigits) + numInt
minSig := int(f.MinFractionDigits) + numInt
n := d.normalize()
if maxSig > 0 {
n.round(ToZero, maxSig)
}
digits := n.Digits
exp := n.Exp
// If a maximum number of integers is specified, the minimum must be 1
// and the exponent is grouped by this number (e.g. for engineering)
if len(digits) == 0 {
exp = 0
} else if maxInt > numInt {
// Correct the exponent to reflect a single integer digit.
exp--
numInt = 1
// engineering
// 0.01234 ([12345]e-1) -> 1.2345e-2 12.345e-3
// 12345 ([12345]e+5) -> 1.2345e4 12.345e3
d := int(exp) % maxInt
if d < 0 {
d += maxInt
}
exp -= int32(d)
numInt += d
} else {
exp -= int32(numInt)
}
var intDigits, fracDigits []byte
if numInt <= len(digits) {
intDigits = digits[:numInt]
fracDigits = digits[numInt:]
} else {
intDigits = digits
}
neg := d.Neg && len(digits) > 0
affix, suffix := f.getAffixes(neg)
dst = appendAffix(dst, f, affix, neg)
savedLen := len(dst)
i := 0
for ; i < len(intDigits); i++ {
dst = f.AppendDigit(dst, intDigits[i])
if f.needsSep(numInt - i) {
dst = append(dst, f.Symbol(SymGroup)...)
}
}
for ; i < numInt; i++ {
dst = f.AppendDigit(dst, 0)
if f.needsSep(numInt - i) {
dst = append(dst, f.Symbol(SymGroup)...)
}
}
trailZero := minSig - numInt - len(fracDigits)
if len(fracDigits) > 0 || trailZero > 0 || f.Flags&AlwaysDecimalSeparator != 0 {
dst = append(dst, f.Symbol(SymDecimal)...)
}
i = 0
for ; i < len(fracDigits); i++ {
dst = f.AppendDigit(dst, fracDigits[i])
}
for ; trailZero > 0; trailZero-- {
dst = f.AppendDigit(dst, 0)
}
// Ensure that at least one digit is written no matter what. This makes
// things more robust, even though a pattern should always require at least
// one fraction or integer digit.
if len(dst) == savedLen {
dst = f.AppendDigit(dst, 0)
}
// exp
dst = append(dst, f.Symbol(SymExponential)...)
switch {
case exp < 0:
dst = append(dst, f.Symbol(SymMinusSign)...)
exp = -exp
case f.Flags&AlwaysExpSign != 0:
dst = append(dst, f.Symbol(SymPlusSign)...)
}
buf := [12]byte{}
b := strconv.AppendUint(buf[:0], uint64(exp), 10)
for i := len(b); i < int(f.MinExponentDigits); i++ {
dst = f.AppendDigit(dst, 0)
}
for _, c := range b {
dst = f.AppendDigit(dst, c-'0')
}
return appendAffix(dst, f, suffix, neg)
}
func (f *Formatter) getAffixes(neg bool) (affix, suffix string) {
str := f.Affix
if str != "" {
if f.NegOffset > 0 {
if neg {
str = str[f.NegOffset:]
} else {
str = str[:f.NegOffset]
}
}
sufStart := 1 + str[0]
affix = str[1:sufStart]
suffix = str[sufStart+1:]
} else if neg {
affix = "-"
}
return affix, suffix
}
func (f *Formatter) renderSpecial(dst []byte, d *Decimal) (b []byte, ok bool) {
if d.NaN {
return fmtNaN(dst, f), true
}
if d.Inf {
return fmtInfinite(dst, f, d), true
}
return dst, false
}
func fmtNaN(dst []byte, f *Formatter) []byte {
return append(dst, f.Symbol(SymNan)...)
}
func fmtInfinite(dst []byte, f *Formatter, d *Decimal) []byte {
if d.Neg {
dst = append(dst, f.Symbol(SymMinusSign)...)
}
return append(dst, f.Symbol(SymInfinity)...)
}
func appendAffix(dst []byte, f *Formatter, affix string, neg bool) []byte {
quoting := false
escaping := false
for _, r := range affix {
switch {
case escaping:
// escaping occurs both inside and outside of quotes
dst = append(dst, string(r)...)
escaping = false
case r == '\\':
escaping = true
case r == '\'':
quoting = !quoting
case !quoting && (r == '-' || r == '+'):
if neg {
dst = append(dst, f.Symbol(SymMinusSign)...)
} else {
dst = append(dst, f.Symbol(SymPlusSign)...)
}
default:
dst = append(dst, string(r)...)
}
}
return dst
}
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