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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"
"unicode/utf8"
"golang.org/x/text/language"
)
// TODO:
// - grouping of fractions
// - allow user-defined superscript notation (such as <sup>4</sup>)
// - same for non-breaking spaces, like &nbsp;
// Formatting proceeds along the following lines:
// 0) Compose rounding information from format and context.
// 1) Convert a number into a Decimal.
// 2) Sanitize Decimal by adding trailing zeros, removing leading digits, and
// (non-increment) rounding. The Decimal that results from this is suitable
// for determining the plural form.
// 3) Render the Decimal in the localized form.
// Formatter contains all the information needed to render a number.
type Formatter struct {
Pattern
Info
RoundingContext
}
func (f *Formatter) init(t language.Tag, index []uint8) {
f.Info = InfoFromTag(t)
for ; ; t = t.Parent() {
if ci, ok := language.CompactIndex(t); ok {
f.Pattern = formats[index[ci]]
break
}
}
}
// InitPattern initializes a Formatter for the given Pattern.
func (f *Formatter) InitPattern(t language.Tag, pat *Pattern) {
f.Info = InfoFromTag(t)
f.Pattern = *pat
}
// InitDecimal initializes a Formatter using the default Pattern for the given
// language.
func (f *Formatter) InitDecimal(t language.Tag) {
f.init(t, tagToDecimal)
}
// InitScientific initializes a Formatter using the default Pattern for the
// given language.
func (f *Formatter) InitScientific(t language.Tag) {
f.init(t, tagToScientific)
}
// InitEngineering initializes a Formatter using the default Pattern for the
// given language.
func (f *Formatter) InitEngineering(t language.Tag) {
f.init(t, tagToScientific)
f.Pattern.MaxIntegerDigits = 3
f.Pattern.MinIntegerDigits = 1
}
// InitPercent initializes a Formatter using the default Pattern for the given
// language.
func (f *Formatter) InitPercent(t language.Tag) {
f.init(t, tagToPercent)
}
// InitPerMille initializes a Formatter using the default Pattern for the given
// language.
func (f *Formatter) InitPerMille(t language.Tag) {
f.init(t, tagToPercent)
f.Pattern.DigitShift = 3
}
func (f *Formatter) Append(dst []byte, x interface{}) []byte {
var d Decimal
d.Convert(&f.RoundingContext, x)
return f.Format(dst, &d)
}
func (f *Formatter) Format(dst []byte, d *Decimal) []byte {
var result []byte
var postPrefix, preSuffix int
if f.MinExponentDigits > 0 {
result, postPrefix, preSuffix = appendScientific(dst, f, d)
} else {
result, postPrefix, preSuffix = appendDecimal(dst, f, d)
}
if f.PadRune == 0 {
return result
}
width := int(f.FormatWidth)
if count := utf8.RuneCount(result); count < width {
insertPos := 0
switch f.Flags & PadMask {
case PadAfterPrefix:
insertPos = postPrefix
case PadBeforeSuffix:
insertPos = preSuffix
case PadAfterSuffix:
insertPos = len(result)
}
num := width - count
pad := [utf8.UTFMax]byte{' '}
sz := 1
if r := f.PadRune; r != 0 {
sz = utf8.EncodeRune(pad[:], r)
}
extra := sz * num
if n := len(result) + extra; n < cap(result) {
result = result[:n]
copy(result[insertPos+extra:], result[insertPos:])
} else {
buf := make([]byte, n)
copy(buf, result[:insertPos])
copy(buf[insertPos+extra:], result[insertPos:])
result = buf
}
for ; num > 0; num-- {
insertPos += copy(result[insertPos:], pad[:sz])
}
}
return result
}
// appendDecimal appends a formatted number to dst. It returns two possible
// insertion points for padding.
func appendDecimal(dst []byte, f *Formatter, d *Decimal) (b []byte, postPre, preSuf int) {
if dst, ok := f.renderSpecial(dst, d); ok {
return dst, 0, len(dst)
}
n := d.normalize()
if maxSig := int(f.MaxSignificantDigits); maxSig > 0 {
n.round(ToZero, maxSig)
}
digits := n.Digits
exp := n.Exp
exp += int32(f.Pattern.DigitShift)
// 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
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 := minInt; i > numInt; i-- {
dst = f.AppendDigit(dst, 0)
if f.needsSep(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)
}
return appendAffix(dst, f, suffix, neg), savedLen, len(dst)
}
// appendScientific appends a formatted number to dst. It returns two possible
// insertion points for padding.
func appendScientific(dst []byte, f *Formatter, d *Decimal) (b []byte, postPre, preSuf int) {
if dst, ok := f.renderSpecial(dst, d); ok {
return dst, 0, 0
}
// 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
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)
}
// exp
buf := [12]byte{}
// TODO: use exponential if superscripting is not available (no Latin
// numbers or no tags) and use exponential in all other cases.
exponential := f.Symbol(SymExponential)
if exponential == "E" {
dst = append(dst, "\u202f"...) // NARROW NO-BREAK SPACE
dst = append(dst, f.Symbol(SymSuperscriptingExponent)...)
dst = append(dst, "\u202f"...) // NARROW NO-BREAK SPACE
dst = f.AppendDigit(dst, 1)
dst = f.AppendDigit(dst, 0)
switch {
case exp < 0:
dst = append(dst, superMinus...)
exp = -exp
case f.Flags&AlwaysExpSign != 0:
dst = append(dst, superPlus...)
}
b = strconv.AppendUint(buf[:0], uint64(exp), 10)
for i := len(b); i < int(f.MinExponentDigits); i++ {
dst = append(dst, superDigits[0]...)
}
for _, c := range b {
dst = append(dst, superDigits[c-'0']...)
}
} else {
dst = append(dst, exponential...)
switch {
case exp < 0:
dst = append(dst, f.Symbol(SymMinusSign)...)
exp = -exp
case f.Flags&AlwaysExpSign != 0:
dst = append(dst, f.Symbol(SymPlusSign)...)
}
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), savedLen, len(dst)
}
const (
superMinus = "\u207B" // SUPERSCRIPT HYPHEN-MINUS
superPlus = "\u207A" // SUPERSCRIPT PLUS SIGN
)
var (
// Note: the digits are not sequential!!!
superDigits = []string{
"\u2070", // SUPERSCRIPT DIGIT ZERO
"\u00B9", // SUPERSCRIPT DIGIT ONE
"\u00B2", // SUPERSCRIPT DIGIT TWO
"\u00B3", // SUPERSCRIPT DIGIT THREE
"\u2074", // SUPERSCRIPT DIGIT FOUR
"\u2075", // SUPERSCRIPT DIGIT FIVE
"\u2076", // SUPERSCRIPT DIGIT SIX
"\u2077", // SUPERSCRIPT DIGIT SEVEN
"\u2078", // SUPERSCRIPT DIGIT EIGHT
"\u2079", // SUPERSCRIPT DIGIT NINE
}
)
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:]
}
// TODO: introduce a NeedNeg sign to indicate if the left pattern already
// has a sign marked?
if f.NegOffset == 0 && (neg || f.Flags&AlwaysSign != 0) {
affix = "-" + 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 {
affix, suffix := f.getAffixes(d.Neg)
dst = appendAffix(dst, f, affix, d.Neg)
dst = append(dst, f.Symbol(SymInfinity)...)
dst = appendAffix(dst, f, suffix, d.Neg)
return dst
}
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:
dst = append(dst, string(r)...)
case r == '%':
if f.DigitShift == 3 {
dst = append(dst, f.Symbol(SymPerMille)...)
} else {
dst = append(dst, f.Symbol(SymPercentSign)...)
}
case r == '-' || r == '+':
if neg {
dst = append(dst, f.Symbol(SymMinusSign)...)
} else if f.Flags&ElideSign == 0 {
dst = append(dst, f.Symbol(SymPlusSign)...)
} else {
dst = append(dst, ' ')
}
default:
dst = append(dst, string(r)...)
}
}
return dst
}