traefik/vendor/golang.org/x/text/cases/map.go
2017-04-07 11:52:18 +01:00

599 lines
17 KiB
Go
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

// 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
}
}