prometheus/vendor/golang.org/x/text/cases/map.go

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// Copyright 2014 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 cases
// This file contains the definitions of case mappings for all supported
// languages. The rules for the language-specific tailorings were taken and
// modified from the CLDR transform definitions in common/transforms.
import (
"strings"
"unicode"
"unicode/utf8"
"golang.org/x/text/language"
"golang.org/x/text/transform"
"golang.org/x/text/unicode/norm"
)
// A mapFunc takes a context set to the current rune and writes the mapped
// version to the same context. It may advance the context to the next rune. It
// returns whether a checkpoint is possible: whether the pDst bytes written to
// dst so far won't need changing as we see more source bytes.
type mapFunc func(*context) bool
// maxIgnorable defines the maximum number of ignorables to consider for
// lookahead operations.
const maxIgnorable = 30
// supported lists the language tags for which we have tailorings.
const supported = "und af az el lt nl tr"
func init() {
tags := []language.Tag{}
for _, s := range strings.Split(supported, " ") {
tags = append(tags, language.MustParse(s))
}
matcher = language.NewMatcher(tags)
Supported = language.NewCoverage(tags)
}
var (
matcher language.Matcher
Supported language.Coverage
// We keep the following lists separate, instead of having a single per-
// language struct, to give the compiler a chance to remove unused code.
// Some uppercase mappers are stateless, so we can precompute the
// Transformers and save a bit on runtime allocations.
upperFunc = []mapFunc{
nil, // und
nil, // af
aztrUpper(upper), // az
elUpper, // el
ltUpper(upper), // lt
nil, // nl
aztrUpper(upper), // tr
}
undUpper transform.Transformer = &undUpperCaser{}
lowerFunc = []mapFunc{
lower, // und
lower, // af
aztrLower, // az
lower, // el
ltLower, // lt
lower, // nl
aztrLower, // tr
}
titleInfos = []struct {
title, lower mapFunc
rewrite func(*context)
}{
{title, lower, nil}, // und
{title, lower, afnlRewrite}, // af
{aztrUpper(title), aztrLower, nil}, // az
{title, lower, nil}, // el
{ltUpper(title), ltLower, nil}, // lt
{nlTitle, lower, afnlRewrite}, // nl
{aztrUpper(title), aztrLower, nil}, // tr
}
)
func makeUpper(t language.Tag, o options) transform.Transformer {
_, i, _ := matcher.Match(t)
f := upperFunc[i]
if f == nil {
return undUpper
}
return &simpleCaser{f: f}
}
func makeLower(t language.Tag, o options) transform.Transformer {
_, i, _ := matcher.Match(t)
f := lowerFunc[i]
if o.noFinalSigma {
return &simpleCaser{f: f}
}
return &lowerCaser{
first: f,
midWord: finalSigma(f),
}
}
func makeTitle(t language.Tag, o options) transform.Transformer {
_, i, _ := matcher.Match(t)
x := &titleInfos[i]
lower := x.lower
if o.noLower {
lower = (*context).copy
} else if !o.noFinalSigma {
lower = finalSigma(lower)
}
return &titleCaser{
title: x.title,
lower: lower,
rewrite: x.rewrite,
}
}
// TODO: consider a similar special case for the fast majority lower case. This
// is a bit more involved so will require some more precise benchmarking to
// justify it.
type undUpperCaser struct{ transform.NopResetter }
// undUpperCaser implements the Transformer interface for doing an upper case
// mapping for the root locale (und). It eliminates the need for an allocation
// as it prevents escaping by not using function pointers.
func (t *undUpperCaser) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
c := context{dst: dst, src: src, atEOF: atEOF}
for c.next() {
upper(&c)
c.checkpoint()
}
return c.ret()
}
type simpleCaser struct {
context
f mapFunc
}
// simpleCaser implements the Transformer interface for doing a case operation
// on a rune-by-rune basis.
func (t *simpleCaser) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
t.context = context{dst: dst, src: src, atEOF: atEOF}
c := &t.context
for c.next() && t.f(c) {
c.checkpoint()
}
return c.ret()
}
// lowerCaser implements the Transformer interface. The default Unicode lower
// casing requires different treatment for the first and subsequent characters
// of a word, most notably to handle the Greek final Sigma.
type lowerCaser struct {
context
first, midWord mapFunc
}
func (t *lowerCaser) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
t.context = context{dst: dst, src: src, atEOF: atEOF}
c := &t.context
for isInterWord := true; c.next(); {
if isInterWord {
if c.info.isCased() {
if !t.first(c) {
break
}
isInterWord = false
} else if !c.copy() {
break
}
} else {
if c.info.isNotCasedAndNotCaseIgnorable() {
if !c.copy() {
break
}
isInterWord = true
} else if !t.midWord(c) {
break
}
}
c.checkpoint()
}
return c.ret()
}
// titleCaser implements the Transformer interface. Title casing algorithms
// distinguish between the first letter of a word and subsequent letters of the
// same word. It uses state to avoid requiring a potentially infinite lookahead.
type titleCaser struct {
context
// rune mappings used by the actual casing algorithms.
title, lower mapFunc
rewrite func(*context)
}
// Transform implements the standard Unicode title case algorithm as defined in
// Chapter 3 of The Unicode Standard:
// toTitlecase(X): Find the word boundaries in X according to Unicode Standard
// Annex #29, "Unicode Text Segmentation." For each word boundary, find the
// first cased character F following the word boundary. If F exists, map F to
// Titlecase_Mapping(F); then map all characters C between F and the following
// word boundary to Lowercase_Mapping(C).
func (t *titleCaser) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
t.context = context{dst: dst, src: src, atEOF: atEOF, isMidWord: t.isMidWord}
c := &t.context
if !c.next() {
return c.ret()
}
for {
p := c.info
if t.rewrite != nil {
t.rewrite(c)
}
wasMid := p.isCaseIgnorableAndNonBreakStarter()
// Break out of this loop on failure to ensure we do not modify the
// state incorrectly.
if p.isCased() && !p.isCaseIgnorableAndNotCased() {
if !c.isMidWord {
if !t.title(c) {
break
}
c.isMidWord = true
} else if !t.lower(c) {
break
}
} else if !c.copy() {
break
}
// TODO: make this an "else if" if we can prove that no rune that does
// not match the first condition of the if statement can be a break.
if p.isBreak() {
c.isMidWord = false
}
// As we save the state of the transformer, it is safe to call
// checkpoint after any successful write.
c.checkpoint()
if !c.next() {
break
}
if wasMid && c.info.isCaseIgnorableAndNonBreakStarter() {
c.isMidWord = false
}
}
return c.ret()
}
// finalSigma adds Greek final Sigma handing to another casing function. It
// determines whether a lowercased sigma should be σ or ς, by looking ahead for
// case-ignorables and a cased letters.
func finalSigma(f mapFunc) mapFunc {
return func(c *context) bool {
// ::NFD();
// # 03A3; 03C2; 03A3; 03A3; Final_Sigma; # GREEK CAPITAL LETTER SIGMA
// Σ } [:case-ignorable:]* [:cased:] → σ;
// [:cased:] [:case-ignorable:]* { Σ → ς;
// ::Any-Lower;
// ::NFC();
if !c.hasPrefix("Σ") {
return f(c)
}
p := c.pDst
c.writeString("ς")
// We need to do one more iteration after maxIgnorable, as a cased
// letter is not an ignorable and may modify the result.
for i := 0; i < maxIgnorable+1; i++ {
if !c.next() {
return false
}
if !c.info.isCaseIgnorable() {
if c.info.isCased() {
// p+1 is guaranteed to be in bounds: if writing ς was
// successful, p+1 will contain the second byte of ς. If not,
// this function will have returned after c.next returned false.
c.dst[p+1]++ // ς → σ
}
c.unreadRune()
return true
}
// A case ignorable may also introduce a word break, so we may need
// to continue searching even after detecting a break.
c.isMidWord = c.isMidWord && !c.info.isBreak()
c.copy()
}
return true
}
}
// elUpper implements Greek upper casing, which entails removing a predefined
// set of non-blocked modifiers. Note that these accents should not be removed
// for title casing!
// Example: "Οδός" -> "ΟΔΟΣ".
func elUpper(c *context) bool {
// From CLDR:
// [:Greek:] [^[:ccc=Not_Reordered:][:ccc=Above:]]*? { [\u0313\u0314\u0301\u0300\u0306\u0342\u0308\u0304] → ;
// [:Greek:] [^[:ccc=Not_Reordered:][:ccc=Iota_Subscript:]]*? { \u0345 → ;
r, _ := utf8.DecodeRune(c.src[c.pSrc:])
oldPDst := c.pDst
if !upper(c) {
return false
}
if !unicode.Is(unicode.Greek, r) {
return true
}
i := 0
// Take the properties of the uppercased rune that is already written to the
// destination. This saves us the trouble of having to uppercase the
// decomposed rune again.
if b := norm.NFD.Properties(c.dst[oldPDst:]).Decomposition(); b != nil {
// Restore the destination position and process the decomposed rune.
r, sz := utf8.DecodeRune(b)
if r <= 0xFF { // See A.6.1
return true
}
c.pDst = oldPDst
// Insert the first rune and ignore the modifiers. See A.6.2.
c.writeBytes(b[:sz])
i = len(b[sz:]) / 2 // Greek modifiers are always of length 2.
}
for ; i < maxIgnorable && c.next(); i++ {
switch r, _ := utf8.DecodeRune(c.src[c.pSrc:]); r {
// Above and Iota Subscript
case 0x0300, // U+0300 COMBINING GRAVE ACCENT
0x0301, // U+0301 COMBINING ACUTE ACCENT
0x0304, // U+0304 COMBINING MACRON
0x0306, // U+0306 COMBINING BREVE
0x0308, // U+0308 COMBINING DIAERESIS
0x0313, // U+0313 COMBINING COMMA ABOVE
0x0314, // U+0314 COMBINING REVERSED COMMA ABOVE
0x0342, // U+0342 COMBINING GREEK PERISPOMENI
0x0345: // U+0345 COMBINING GREEK YPOGEGRAMMENI
// No-op. Gobble the modifier.
default:
switch v, _ := trie.lookup(c.src[c.pSrc:]); info(v).cccType() {
case cccZero:
c.unreadRune()
return true
// We don't need to test for IotaSubscript as the only rune that
// qualifies (U+0345) was already excluded in the switch statement
// above. See A.4.
case cccAbove:
return c.copy()
default:
// Some other modifier. We're still allowed to gobble Greek
// modifiers after this.
c.copy()
}
}
}
return i == maxIgnorable
}
func ltLower(c *context) bool {
// From CLDR:
// # Introduce an explicit dot above when lowercasing capital I's and J's
// # whenever there are more accents above.
// # (of the accents used in Lithuanian: grave, acute, tilde above, and ogonek)
// # 0049; 0069 0307; 0049; 0049; lt More_Above; # LATIN CAPITAL LETTER I
// # 004A; 006A 0307; 004A; 004A; lt More_Above; # LATIN CAPITAL LETTER J
// # 012E; 012F 0307; 012E; 012E; lt More_Above; # LATIN CAPITAL LETTER I WITH OGONEK
// # 00CC; 0069 0307 0300; 00CC; 00CC; lt; # LATIN CAPITAL LETTER I WITH GRAVE
// # 00CD; 0069 0307 0301; 00CD; 00CD; lt; # LATIN CAPITAL LETTER I WITH ACUTE
// # 0128; 0069 0307 0303; 0128; 0128; lt; # LATIN CAPITAL LETTER I WITH TILDE
// ::NFD();
// I } [^[:ccc=Not_Reordered:][:ccc=Above:]]* [:ccc=Above:] → i \u0307;
// J } [^[:ccc=Not_Reordered:][:ccc=Above:]]* [:ccc=Above:] → j \u0307;
// Į } [^[:ccc=Not_Reordered:][:ccc=Above:]]* [:ccc=Above:] → į \u0307;
// Ì → i \u0307 \u0300;
// Í → i \u0307 \u0301;
// Ĩ → i \u0307 \u0303;
// ::Any-Lower();
// ::NFC();
i := 0
if r := c.src[c.pSrc]; r < utf8.RuneSelf {
lower(c)
if r != 'I' && r != 'J' {
return true
}
} else {
p := norm.NFD.Properties(c.src[c.pSrc:])
if d := p.Decomposition(); len(d) >= 3 && (d[0] == 'I' || d[0] == 'J') {
// UTF-8 optimization: the decomposition will only have an above
// modifier if the last rune of the decomposition is in [U+300-U+311].
// In all other cases, a decomposition starting with I is always
// an I followed by modifiers that are not cased themselves. See A.2.
if d[1] == 0xCC && d[2] <= 0x91 { // A.2.4.
if !c.writeBytes(d[:1]) {
return false
}
c.dst[c.pDst-1] += 'a' - 'A' // lower
// Assumption: modifier never changes on lowercase. See A.1.
// Assumption: all modifiers added have CCC = Above. See A.2.3.
return c.writeString("\u0307") && c.writeBytes(d[1:])
}
// In all other cases the additional modifiers will have a CCC
// that is less than 230 (Above). We will insert the U+0307, if
// needed, after these modifiers so that a string in FCD form
// will remain so. See A.2.2.
lower(c)
i = 1
} else {
return lower(c)
}
}
for ; i < maxIgnorable && c.next(); i++ {
switch c.info.cccType() {
case cccZero:
c.unreadRune()
return true
case cccAbove:
return c.writeString("\u0307") && c.copy() // See A.1.
default:
c.copy() // See A.1.
}
}
return i == maxIgnorable
}
func ltUpper(f mapFunc) mapFunc {
return func(c *context) bool {
// From CLDR:
// ::NFD();
// [:Soft_Dotted:] [^[:ccc=Not_Reordered:][:ccc=Above:]]* { \u0307 → ;
// ::Any-Upper();
// ::NFC();
// TODO: See A.5. A soft-dotted rune never has an exception. This would
// allow us to overload the exception bit and encode this property in
// info. Need to measure performance impact of this.
r, _ := utf8.DecodeRune(c.src[c.pSrc:])
oldPDst := c.pDst
if !f(c) {
return false
}
if !unicode.Is(unicode.Soft_Dotted, r) {
return true
}
// We don't need to do an NFD normalization, as a soft-dotted rune never
// contains U+0307. See A.3.
i := 0
for ; i < maxIgnorable && c.next(); i++ {
switch c.info.cccType() {
case cccZero:
c.unreadRune()
return true
case cccAbove:
if c.hasPrefix("\u0307") {
// We don't do a full NFC, but rather combine runes for
// some of the common cases. (Returning NFC or
// preserving normal form is neither a requirement nor
// a possibility anyway).
if !c.next() {
return false
}
if c.dst[oldPDst] == 'I' && c.pDst == oldPDst+1 && c.src[c.pSrc] == 0xcc {
s := ""
switch c.src[c.pSrc+1] {
case 0x80: // U+0300 COMBINING GRAVE ACCENT
s = "\u00cc" // U+00CC LATIN CAPITAL LETTER I WITH GRAVE
case 0x81: // U+0301 COMBINING ACUTE ACCENT
s = "\u00cd" // U+00CD LATIN CAPITAL LETTER I WITH ACUTE
case 0x83: // U+0303 COMBINING TILDE
s = "\u0128" // U+0128 LATIN CAPITAL LETTER I WITH TILDE
case 0x88: // U+0308 COMBINING DIAERESIS
s = "\u00cf" // U+00CF LATIN CAPITAL LETTER I WITH DIAERESIS
default:
}
if s != "" {
c.pDst = oldPDst
return c.writeString(s)
}
}
}
return c.copy()
default:
c.copy()
}
}
return i == maxIgnorable
}
}
func aztrUpper(f mapFunc) mapFunc {
return func(c *context) bool {
// i→İ;
if c.src[c.pSrc] == 'i' {
return c.writeString("İ")
}
return f(c)
}
}
func aztrLower(c *context) (done bool) {
// From CLDR:
// # I and i-dotless; I-dot and i are case pairs in Turkish and Azeri
// # 0130; 0069; 0130; 0130; tr; # LATIN CAPITAL LETTER I WITH DOT ABOVE
// İ→i;
// # When lowercasing, remove dot_above in the sequence I + dot_above, which will turn into i.
// # This matches the behavior of the canonically equivalent I-dot_above
// # 0307; ; 0307; 0307; tr After_I; # COMBINING DOT ABOVE
// # When lowercasing, unless an I is before a dot_above, it turns into a dotless i.
// # 0049; 0131; 0049; 0049; tr Not_Before_Dot; # LATIN CAPITAL LETTER I
// I([^[:ccc=Not_Reordered:][:ccc=Above:]]*)\u0307 → i$1 ;
// I→ı ;
// ::Any-Lower();
if c.hasPrefix("\u0130") { // İ
return c.writeString("i")
}
if c.src[c.pSrc] != 'I' {
return lower(c)
}
// We ignore the lower-case I for now, but insert it later when we know
// which form we need.
start := c.pSrc + c.sz
i := 0
Loop:
// We check for up to n ignorables before \u0307. As \u0307 is an
// ignorable as well, n is maxIgnorable-1.
for ; i < maxIgnorable && c.next(); i++ {
switch c.info.cccType() {
case cccAbove:
if c.hasPrefix("\u0307") {
return c.writeString("i") && c.writeBytes(c.src[start:c.pSrc]) // ignore U+0307
}
done = true
break Loop
case cccZero:
c.unreadRune()
done = true
break Loop
default:
// We'll write this rune after we know which starter to use.
}
}
if i == maxIgnorable {
done = true
}
return c.writeString("ı") && c.writeBytes(c.src[start:c.pSrc+c.sz]) && done
}
func nlTitle(c *context) bool {
// From CLDR:
// # Special titlecasing for Dutch initial "ij".
// ::Any-Title();
// # Fix up Ij at the beginning of a "word" (per Any-Title, notUAX #29)
// [:^WB=ALetter:] [:WB=Extend:]* [[:WB=MidLetter:][:WB=MidNumLet:]]? { Ij } → IJ ;
if c.src[c.pSrc] != 'I' && c.src[c.pSrc] != 'i' {
return title(c)
}
if !c.writeString("I") || !c.next() {
return false
}
if c.src[c.pSrc] == 'j' || c.src[c.pSrc] == 'J' {
return c.writeString("J")
}
c.unreadRune()
return true
}
// Not part of CLDR, but see http://unicode.org/cldr/trac/ticket/7078.
func afnlRewrite(c *context) {
if c.hasPrefix("'") || c.hasPrefix("") {
c.isMidWord = true
}
}