More expansions in template repositories (#10021)

* Super expansion
* Explain which features are in 1.11 vs 1.12
* Move imports

Signed-off-by: jolheiser <john.olheiser@gmail.com>

vendor/github.com/huandu/xstrings/convert.go

@@ -0,0 +1,404 @@
+// Copyright 2015 Huan Du. All rights reserved.
+// Licensed under the MIT license that can be found in the LICENSE file.
+
+package xstrings
+
+import (
+	"bytes"
+	"math/rand"
+	"unicode"
+	"unicode/utf8"
+)
+
+// ToCamelCase is to convert words separated by space, underscore and hyphen to camel case.
+//
+// Some samples.
+//     "some_words"      => "SomeWords"
+//     "http_server"     => "HttpServer"
+//     "no_https"        => "NoHttps"
+//     "_complex__case_" => "_Complex_Case_"
+//     "some words"      => "SomeWords"
+func ToCamelCase(str string) string {
+	if len(str) == 0 {
+		return ""
+	}
+
+	buf := &bytes.Buffer{}
+	var r0, r1 rune
+	var size int
+
+	// leading connector will appear in output.
+	for len(str) > 0 {
+		r0, size = utf8.DecodeRuneInString(str)
+		str = str[size:]
+
+		if !isConnector(r0) {
+			r0 = unicode.ToUpper(r0)
+			break
+		}
+
+		buf.WriteRune(r0)
+	}
+
+	if len(str) == 0 {
+		// A special case for a string contains only 1 rune.
+		if size != 0 {
+			buf.WriteRune(r0)
+		}
+
+		return buf.String()
+	}
+
+	for len(str) > 0 {
+		r1 = r0
+		r0, size = utf8.DecodeRuneInString(str)
+		str = str[size:]
+
+		if isConnector(r0) && isConnector(r1) {
+			buf.WriteRune(r1)
+			continue
+		}
+
+		if isConnector(r1) {
+			r0 = unicode.ToUpper(r0)
+		} else {
+			r0 = unicode.ToLower(r0)
+			buf.WriteRune(r1)
+		}
+	}
+
+	buf.WriteRune(r0)
+	return buf.String()
+}
+
+// ToSnakeCase can convert all upper case characters in a string to
+// snake case format.
+//
+// Some samples.
+//     "FirstName"  => "first_name"
+//     "HTTPServer" => "http_server"
+//     "NoHTTPS"    => "no_https"
+//     "GO_PATH"    => "go_path"
+//     "GO PATH"    => "go_path"      // space is converted to underscore.
+//     "GO-PATH"    => "go_path"      // hyphen is converted to underscore.
+//     "HTTP2XX"    => "http_2xx"     // insert an underscore before a number and after an alphabet.
+//     "http2xx"    => "http_2xx"
+//     "HTTP20xOK"  => "http_20x_ok"
+func ToSnakeCase(str string) string {
+	return camelCaseToLowerCase(str, '_')
+}
+
+// ToKebabCase can convert all upper case characters in a string to
+// kebab case format.
+//
+// Some samples.
+//     "FirstName"  => "first-name"
+//     "HTTPServer" => "http-server"
+//     "NoHTTPS"    => "no-https"
+//     "GO_PATH"    => "go-path"
+//     "GO PATH"    => "go-path"      // space is converted to '-'.
+//     "GO-PATH"    => "go-path"      // hyphen is converted to '-'.
+//     "HTTP2XX"    => "http-2xx"     // insert a '-' before a number and after an alphabet.
+//     "http2xx"    => "http-2xx"
+//     "HTTP20xOK"  => "http-20x-ok"
+func ToKebabCase(str string) string {
+	return camelCaseToLowerCase(str, '-')
+}
+
+func camelCaseToLowerCase(str string, connector rune) string {
+	if len(str) == 0 {
+		return ""
+	}
+
+	buf := &bytes.Buffer{}
+	var prev, r0, r1 rune
+	var size int
+
+	r0 = connector
+
+	for len(str) > 0 {
+		prev = r0
+		r0, size = utf8.DecodeRuneInString(str)
+		str = str[size:]
+
+		switch {
+		case r0 == utf8.RuneError:
+			buf.WriteRune(r0)
+
+		case unicode.IsUpper(r0):
+			if prev != connector && !unicode.IsNumber(prev) {
+				buf.WriteRune(connector)
+			}
+
+			buf.WriteRune(unicode.ToLower(r0))
+
+			if len(str) == 0 {
+				break
+			}
+
+			r0, size = utf8.DecodeRuneInString(str)
+			str = str[size:]
+
+			if !unicode.IsUpper(r0) {
+				buf.WriteRune(r0)
+				break
+			}
+
+			// find next non-upper-case character and insert connector properly.
+			// it's designed to convert `HTTPServer` to `http_server`.
+			// if there are more than 2 adjacent upper case characters in a word,
+			// treat them as an abbreviation plus a normal word.
+			for len(str) > 0 {
+				r1 = r0
+				r0, size = utf8.DecodeRuneInString(str)
+				str = str[size:]
+
+				if r0 == utf8.RuneError {
+					buf.WriteRune(unicode.ToLower(r1))
+					buf.WriteRune(r0)
+					break
+				}
+
+				if !unicode.IsUpper(r0) {
+					if isConnector(r0) {
+						r0 = connector
+
+						buf.WriteRune(unicode.ToLower(r1))
+					} else if unicode.IsNumber(r0) {
+						// treat a number as an upper case rune
+						// so that both `http2xx` and `HTTP2XX` can be converted to `http_2xx`.
+						buf.WriteRune(unicode.ToLower(r1))
+						buf.WriteRune(connector)
+						buf.WriteRune(r0)
+					} else {
+						buf.WriteRune(connector)
+						buf.WriteRune(unicode.ToLower(r1))
+						buf.WriteRune(r0)
+					}
+
+					break
+				}
+
+				buf.WriteRune(unicode.ToLower(r1))
+			}
+
+			if len(str) == 0 || r0 == connector {
+				buf.WriteRune(unicode.ToLower(r0))
+			}
+
+		case unicode.IsNumber(r0):
+			if prev != connector && !unicode.IsNumber(prev) {
+				buf.WriteRune(connector)
+			}
+
+			buf.WriteRune(r0)
+
+		default:
+			if isConnector(r0) {
+				r0 = connector
+			}
+
+			buf.WriteRune(r0)
+		}
+	}
+
+	return buf.String()
+}
+
+func isConnector(r rune) bool {
+	return r == '-' || r == '_' || unicode.IsSpace(r)
+}
+
+// SwapCase will swap characters case from upper to lower or lower to upper.
+func SwapCase(str string) string {
+	var r rune
+	var size int
+
+	buf := &bytes.Buffer{}
+
+	for len(str) > 0 {
+		r, size = utf8.DecodeRuneInString(str)
+
+		switch {
+		case unicode.IsUpper(r):
+			buf.WriteRune(unicode.ToLower(r))
+
+		case unicode.IsLower(r):
+			buf.WriteRune(unicode.ToUpper(r))
+
+		default:
+			buf.WriteRune(r)
+		}
+
+		str = str[size:]
+	}
+
+	return buf.String()
+}
+
+// FirstRuneToUpper converts first rune to upper case if necessary.
+func FirstRuneToUpper(str string) string {
+	if str == "" {
+		return str
+	}
+
+	r, size := utf8.DecodeRuneInString(str)
+
+	if !unicode.IsLower(r) {
+		return str
+	}
+
+	buf := &bytes.Buffer{}
+	buf.WriteRune(unicode.ToUpper(r))
+	buf.WriteString(str[size:])
+	return buf.String()
+}
+
+// FirstRuneToLower converts first rune to lower case if necessary.
+func FirstRuneToLower(str string) string {
+	if str == "" {
+		return str
+	}
+
+	r, size := utf8.DecodeRuneInString(str)
+
+	if !unicode.IsUpper(r) {
+		return str
+	}
+
+	buf := &bytes.Buffer{}
+	buf.WriteRune(unicode.ToLower(r))
+	buf.WriteString(str[size:])
+	return buf.String()
+}
+
+// Shuffle randomizes runes in a string and returns the result.
+// It uses default random source in `math/rand`.
+func Shuffle(str string) string {
+	if str == "" {
+		return str
+	}
+
+	runes := []rune(str)
+	index := 0
+
+	for i := len(runes) - 1; i > 0; i-- {
+		index = rand.Intn(i + 1)
+
+		if i != index {
+			runes[i], runes[index] = runes[index], runes[i]
+		}
+	}
+
+	return string(runes)
+}
+
+// ShuffleSource randomizes runes in a string with given random source.
+func ShuffleSource(str string, src rand.Source) string {
+	if str == "" {
+		return str
+	}
+
+	runes := []rune(str)
+	index := 0
+	r := rand.New(src)
+
+	for i := len(runes) - 1; i > 0; i-- {
+		index = r.Intn(i + 1)
+
+		if i != index {
+			runes[i], runes[index] = runes[index], runes[i]
+		}
+	}
+
+	return string(runes)
+}
+
+// Successor returns the successor to string.
+//
+// If there is one alphanumeric rune is found in string, increase the rune by 1.
+// If increment generates a "carry", the rune to the left of it is incremented.
+// This process repeats until there is no carry, adding an additional rune if necessary.
+//
+// If there is no alphanumeric rune, the rightmost rune will be increased by 1
+// regardless whether the result is a valid rune or not.
+//
+// Only following characters are alphanumeric.
+//     * a - z
+//     * A - Z
+//     * 0 - 9
+//
+// Samples (borrowed from ruby's String#succ document):
+//     "abcd"      => "abce"
+//     "THX1138"   => "THX1139"
+//     "<<koala>>" => "<<koalb>>"
+//     "1999zzz"   => "2000aaa"
+//     "ZZZ9999"   => "AAAA0000"
+//     "***"       => "**+"
+func Successor(str string) string {
+	if str == "" {
+		return str
+	}
+
+	var r rune
+	var i int
+	carry := ' '
+	runes := []rune(str)
+	l := len(runes)
+	lastAlphanumeric := l
+
+	for i = l - 1; i >= 0; i-- {
+		r = runes[i]
+
+		if ('a' <= r && r <= 'y') ||
+			('A' <= r && r <= 'Y') ||
+			('0' <= r && r <= '8') {
+			runes[i]++
+			carry = ' '
+			lastAlphanumeric = i
+			break
+		}
+
+		switch r {
+		case 'z':
+			runes[i] = 'a'
+			carry = 'a'
+			lastAlphanumeric = i
+
+		case 'Z':
+			runes[i] = 'A'
+			carry = 'A'
+			lastAlphanumeric = i
+
+		case '9':
+			runes[i] = '0'
+			carry = '0'
+			lastAlphanumeric = i
+		}
+	}
+
+	// Needs to add one character for carry.
+	if i < 0 && carry != ' ' {
+		buf := &bytes.Buffer{}
+		buf.Grow(l + 4) // Reserve enough space for write.
+
+		if lastAlphanumeric != 0 {
+			buf.WriteString(str[:lastAlphanumeric])
+		}
+
+		buf.WriteRune(carry)
+
+		for _, r = range runes[lastAlphanumeric:] {
+			buf.WriteRune(r)
+		}
+
+		return buf.String()
+	}
+
+	// No alphanumeric character. Simply increase last rune's value.
+	if lastAlphanumeric == l {
+		runes[l-1]++
+	}
+
+	return string(runes)
+}