Vendor update

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

@@ -0,0 +1,599 @@
+// 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
+	}
+}