restic/vendor/golang.org/x/text/internal/number/number.go

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// Copyright 2016 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.
//go:generate go run gen.go gen_common.go
// Package number contains tools and data for formatting numbers.
package number
import (
"unicode/utf8"
"golang.org/x/text/internal"
"golang.org/x/text/language"
)
// Info holds number formatting configuration data.
type Info struct {
system systemData // numbering system information
symIndex symOffset // index to symbols
}
// InfoFromLangID returns a Info for the given compact language identifier and
// numbering system identifier. If system is the empty string, the default
// numbering system will be taken for that language.
func InfoFromLangID(compactIndex int, numberSystem string) Info {
p := langToDefaults[compactIndex]
// Lookup the entry for the language.
pSymIndex := symOffset(0) // Default: Latin, default symbols
system, ok := systemMap[numberSystem]
if !ok {
// Take the value for the default numbering system. This is by far the
// most common case as an alternative numbering system is hardly used.
if p&hasNonLatnMask == 0 { // Latn digits.
pSymIndex = p
} else { // Non-Latn or multiple numbering systems.
// Take the first entry from the alternatives list.
data := langToAlt[p&^hasNonLatnMask]
pSymIndex = data.symIndex
system = data.system
}
} else {
langIndex := compactIndex
ns := system
outerLoop:
for ; ; p = langToDefaults[langIndex] {
if p&hasNonLatnMask == 0 {
if ns == 0 {
// The index directly points to the symbol data.
pSymIndex = p
break
}
// Move to the parent and retry.
langIndex = int(internal.Parent[langIndex])
} else {
// The index points to a list of symbol data indexes.
for _, e := range langToAlt[p&^hasNonLatnMask:] {
if int(e.compactTag) != langIndex {
if langIndex == 0 {
// The CLDR root defines full symbol information for
// all numbering systems (even though mostly by
// means of aliases). Fall back to the default entry
// for Latn if there is no data for the numbering
// system of this language.
if ns == 0 {
break
}
// Fall back to Latin and start from the original
// language. See
// http://unicode.org/reports/tr35/#Locale_Inheritance.
ns = numLatn
langIndex = compactIndex
continue outerLoop
}
// Fall back to parent.
langIndex = int(internal.Parent[langIndex])
} else if e.system == ns {
pSymIndex = e.symIndex
break outerLoop
}
}
}
}
}
if int(system) >= len(numSysData) { // algorithmic
// Will generate ASCII digits in case the user inadvertently calls
// WriteDigit or Digit on it.
d := numSysData[0]
d.id = system
return Info{
system: d,
symIndex: pSymIndex,
}
}
return Info{
system: numSysData[system],
symIndex: pSymIndex,
}
}
// InfoFromTag returns a Info for the given language tag.
func InfoFromTag(t language.Tag) Info {
for {
if index, ok := language.CompactIndex(t); ok {
return InfoFromLangID(index, t.TypeForKey("nu"))
}
t = t.Parent()
}
}
// IsDecimal reports if the numbering system can convert decimal to native
// symbols one-to-one.
func (n Info) IsDecimal() bool {
return int(n.system.id) < len(numSysData)
}
// WriteDigit writes the UTF-8 sequence for n corresponding to the given ASCII
// digit to dst and reports the number of bytes written. dst must be large
// enough to hold the rune (can be up to utf8.UTFMax bytes).
func (n Info) WriteDigit(dst []byte, asciiDigit rune) int {
copy(dst, n.system.zero[:n.system.digitSize])
dst[n.system.digitSize-1] += byte(asciiDigit - '0')
return int(n.system.digitSize)
}
// AppendDigit appends the UTF-8 sequence for n corresponding to the given digit
// to dst and reports the number of bytes written. dst must be large enough to
// hold the rune (can be up to utf8.UTFMax bytes).
func (n Info) AppendDigit(dst []byte, digit byte) []byte {
dst = append(dst, n.system.zero[:n.system.digitSize]...)
dst[len(dst)-1] += digit
return dst
}
// Digit returns the digit for the numbering system for the corresponding ASCII
// value. For example, ni.Digit('3') could return '三'. Note that the argument
// is the rune constant '3', which equals 51, not the integer constant 3.
func (n Info) Digit(asciiDigit rune) rune {
var x [utf8.UTFMax]byte
n.WriteDigit(x[:], asciiDigit)
r, _ := utf8.DecodeRune(x[:])
return r
}
// Symbol returns the string for the given symbol type.
func (n Info) Symbol(t SymbolType) string {
return symData.Elem(int(symIndex[n.symIndex][t]))
}
func formatForLang(t language.Tag, index []byte) *Pattern {
for ; ; t = t.Parent() {
if x, ok := language.CompactIndex(t); ok {
return &formats[index[x]]
}
}
}