594 lines
11 KiB
Go
594 lines
11 KiB
Go
// Copyright 2015 Huan Du. All rights reserved.
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// Licensed under the MIT license that can be found in the LICENSE file.
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package xstrings
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import (
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"math/rand"
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"unicode"
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"unicode/utf8"
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)
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// ToCamelCase is to convert words separated by space, underscore and hyphen to camel case.
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//
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// Some samples.
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//
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// "some_words" => "SomeWords"
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// "http_server" => "HttpServer"
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// "no_https" => "NoHttps"
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// "_complex__case_" => "_Complex_Case_"
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// "some words" => "SomeWords"
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func ToCamelCase(str string) string {
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if len(str) == 0 {
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return ""
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}
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buf := &stringBuilder{}
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var r0, r1 rune
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var size int
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// leading connector will appear in output.
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for len(str) > 0 {
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r0, size = utf8.DecodeRuneInString(str)
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str = str[size:]
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if !isConnector(r0) {
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r0 = unicode.ToUpper(r0)
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break
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}
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buf.WriteRune(r0)
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}
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if len(str) == 0 {
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// A special case for a string contains only 1 rune.
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if size != 0 {
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buf.WriteRune(r0)
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}
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return buf.String()
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}
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for len(str) > 0 {
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r1 = r0
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r0, size = utf8.DecodeRuneInString(str)
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str = str[size:]
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if isConnector(r0) && isConnector(r1) {
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buf.WriteRune(r1)
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continue
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}
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if isConnector(r1) {
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r0 = unicode.ToUpper(r0)
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} else {
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buf.WriteRune(r1)
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}
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}
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buf.WriteRune(r0)
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return buf.String()
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}
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// ToSnakeCase can convert all upper case characters in a string to
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// snake case format.
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//
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// Some samples.
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//
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// "FirstName" => "first_name"
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// "HTTPServer" => "http_server"
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// "NoHTTPS" => "no_https"
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// "GO_PATH" => "go_path"
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// "GO PATH" => "go_path" // space is converted to underscore.
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// "GO-PATH" => "go_path" // hyphen is converted to underscore.
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// "http2xx" => "http_2xx" // insert an underscore before a number and after an alphabet.
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// "HTTP20xOK" => "http_20x_ok"
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// "Duration2m3s" => "duration_2m3s"
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// "Bld4Floor3rd" => "bld4_floor_3rd"
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func ToSnakeCase(str string) string {
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return camelCaseToLowerCase(str, '_')
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}
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// ToKebabCase can convert all upper case characters in a string to
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// kebab case format.
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//
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// Some samples.
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//
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// "FirstName" => "first-name"
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// "HTTPServer" => "http-server"
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// "NoHTTPS" => "no-https"
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// "GO_PATH" => "go-path"
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// "GO PATH" => "go-path" // space is converted to '-'.
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// "GO-PATH" => "go-path" // hyphen is converted to '-'.
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// "http2xx" => "http-2xx" // insert an underscore before a number and after an alphabet.
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// "HTTP20xOK" => "http-20x-ok"
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// "Duration2m3s" => "duration-2m3s"
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// "Bld4Floor3rd" => "bld4-floor-3rd"
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func ToKebabCase(str string) string {
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return camelCaseToLowerCase(str, '-')
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}
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func camelCaseToLowerCase(str string, connector rune) string {
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if len(str) == 0 {
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return ""
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}
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buf := &stringBuilder{}
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wt, word, remaining := nextWord(str)
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for len(remaining) > 0 {
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if wt != connectorWord {
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toLower(buf, wt, word, connector)
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}
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prev := wt
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last := word
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wt, word, remaining = nextWord(remaining)
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switch prev {
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case numberWord:
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for wt == alphabetWord || wt == numberWord {
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toLower(buf, wt, word, connector)
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wt, word, remaining = nextWord(remaining)
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}
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if wt != invalidWord && wt != punctWord && wt != connectorWord {
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buf.WriteRune(connector)
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}
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case connectorWord:
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toLower(buf, prev, last, connector)
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case punctWord:
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// nothing.
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default:
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if wt != numberWord {
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if wt != connectorWord && wt != punctWord {
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buf.WriteRune(connector)
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}
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break
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}
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if len(remaining) == 0 {
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break
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}
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last := word
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wt, word, remaining = nextWord(remaining)
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// consider number as a part of previous word.
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// e.g. "Bld4Floor" => "bld4_floor"
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if wt != alphabetWord {
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toLower(buf, numberWord, last, connector)
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if wt != connectorWord && wt != punctWord {
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buf.WriteRune(connector)
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}
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break
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}
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// if there are some lower case letters following a number,
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// add connector before the number.
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// e.g. "HTTP2xx" => "http_2xx"
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buf.WriteRune(connector)
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toLower(buf, numberWord, last, connector)
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for wt == alphabetWord || wt == numberWord {
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toLower(buf, wt, word, connector)
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wt, word, remaining = nextWord(remaining)
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}
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if wt != invalidWord && wt != connectorWord && wt != punctWord {
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buf.WriteRune(connector)
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}
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}
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}
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toLower(buf, wt, word, connector)
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return buf.String()
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}
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func isConnector(r rune) bool {
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return r == '-' || r == '_' || unicode.IsSpace(r)
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}
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type wordType int
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const (
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invalidWord wordType = iota
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numberWord
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upperCaseWord
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alphabetWord
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connectorWord
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punctWord
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otherWord
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)
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func nextWord(str string) (wt wordType, word, remaining string) {
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if len(str) == 0 {
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return
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}
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var offset int
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remaining = str
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r, size := nextValidRune(remaining, utf8.RuneError)
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offset += size
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if r == utf8.RuneError {
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wt = invalidWord
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word = str[:offset]
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remaining = str[offset:]
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return
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}
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switch {
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case isConnector(r):
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wt = connectorWord
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remaining = remaining[size:]
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for len(remaining) > 0 {
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r, size = nextValidRune(remaining, r)
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if !isConnector(r) {
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break
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}
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offset += size
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remaining = remaining[size:]
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}
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case unicode.IsPunct(r):
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wt = punctWord
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remaining = remaining[size:]
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for len(remaining) > 0 {
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r, size = nextValidRune(remaining, r)
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if !unicode.IsPunct(r) {
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break
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}
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offset += size
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remaining = remaining[size:]
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}
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case unicode.IsUpper(r):
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wt = upperCaseWord
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remaining = remaining[size:]
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if len(remaining) == 0 {
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break
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}
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r, size = nextValidRune(remaining, r)
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switch {
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case unicode.IsUpper(r):
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prevSize := size
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offset += size
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remaining = remaining[size:]
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for len(remaining) > 0 {
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r, size = nextValidRune(remaining, r)
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if !unicode.IsUpper(r) {
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break
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}
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prevSize = size
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offset += size
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remaining = remaining[size:]
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}
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// it's a bit complex when dealing with a case like "HTTPStatus".
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// it's expected to be splitted into "HTTP" and "Status".
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// Therefore "S" should be in remaining instead of word.
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if len(remaining) > 0 && isAlphabet(r) {
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offset -= prevSize
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remaining = str[offset:]
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}
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case isAlphabet(r):
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offset += size
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remaining = remaining[size:]
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for len(remaining) > 0 {
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r, size = nextValidRune(remaining, r)
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if !isAlphabet(r) || unicode.IsUpper(r) {
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break
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}
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offset += size
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remaining = remaining[size:]
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}
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}
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case isAlphabet(r):
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wt = alphabetWord
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remaining = remaining[size:]
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for len(remaining) > 0 {
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r, size = nextValidRune(remaining, r)
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if !isAlphabet(r) || unicode.IsUpper(r) {
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break
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}
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offset += size
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remaining = remaining[size:]
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}
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case unicode.IsNumber(r):
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wt = numberWord
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remaining = remaining[size:]
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for len(remaining) > 0 {
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r, size = nextValidRune(remaining, r)
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if !unicode.IsNumber(r) {
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break
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}
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offset += size
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remaining = remaining[size:]
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}
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default:
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wt = otherWord
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remaining = remaining[size:]
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for len(remaining) > 0 {
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r, size = nextValidRune(remaining, r)
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if size == 0 || isConnector(r) || isAlphabet(r) || unicode.IsNumber(r) || unicode.IsPunct(r) {
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break
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}
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offset += size
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remaining = remaining[size:]
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}
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}
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word = str[:offset]
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return
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}
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func nextValidRune(str string, prev rune) (r rune, size int) {
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var sz int
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for len(str) > 0 {
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r, sz = utf8.DecodeRuneInString(str)
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size += sz
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if r != utf8.RuneError {
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return
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}
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str = str[sz:]
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}
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r = prev
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return
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}
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func toLower(buf *stringBuilder, wt wordType, str string, connector rune) {
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buf.Grow(buf.Len() + len(str))
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if wt != upperCaseWord && wt != connectorWord {
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buf.WriteString(str)
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return
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}
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for len(str) > 0 {
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r, size := utf8.DecodeRuneInString(str)
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str = str[size:]
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if isConnector(r) {
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buf.WriteRune(connector)
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} else if unicode.IsUpper(r) {
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buf.WriteRune(unicode.ToLower(r))
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} else {
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buf.WriteRune(r)
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}
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}
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}
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// SwapCase will swap characters case from upper to lower or lower to upper.
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func SwapCase(str string) string {
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var r rune
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var size int
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buf := &stringBuilder{}
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for len(str) > 0 {
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r, size = utf8.DecodeRuneInString(str)
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switch {
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case unicode.IsUpper(r):
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buf.WriteRune(unicode.ToLower(r))
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case unicode.IsLower(r):
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buf.WriteRune(unicode.ToUpper(r))
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default:
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buf.WriteRune(r)
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}
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str = str[size:]
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}
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return buf.String()
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}
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// FirstRuneToUpper converts first rune to upper case if necessary.
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func FirstRuneToUpper(str string) string {
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if str == "" {
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return str
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}
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r, size := utf8.DecodeRuneInString(str)
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if !unicode.IsLower(r) {
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return str
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}
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buf := &stringBuilder{}
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buf.WriteRune(unicode.ToUpper(r))
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buf.WriteString(str[size:])
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return buf.String()
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}
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// FirstRuneToLower converts first rune to lower case if necessary.
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func FirstRuneToLower(str string) string {
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if str == "" {
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return str
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}
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r, size := utf8.DecodeRuneInString(str)
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if !unicode.IsUpper(r) {
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return str
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}
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buf := &stringBuilder{}
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buf.WriteRune(unicode.ToLower(r))
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buf.WriteString(str[size:])
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return buf.String()
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}
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// Shuffle randomizes runes in a string and returns the result.
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// It uses default random source in `math/rand`.
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func Shuffle(str string) string {
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if str == "" {
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return str
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}
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runes := []rune(str)
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index := 0
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for i := len(runes) - 1; i > 0; i-- {
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index = rand.Intn(i + 1)
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if i != index {
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runes[i], runes[index] = runes[index], runes[i]
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}
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}
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return string(runes)
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}
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// ShuffleSource randomizes runes in a string with given random source.
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func ShuffleSource(str string, src rand.Source) string {
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if str == "" {
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return str
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}
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runes := []rune(str)
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index := 0
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r := rand.New(src)
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for i := len(runes) - 1; i > 0; i-- {
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index = r.Intn(i + 1)
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if i != index {
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runes[i], runes[index] = runes[index], runes[i]
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}
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}
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return string(runes)
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}
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// Successor returns the successor to string.
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//
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// If there is one alphanumeric rune is found in string, increase the rune by 1.
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// If increment generates a "carry", the rune to the left of it is incremented.
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// This process repeats until there is no carry, adding an additional rune if necessary.
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//
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// If there is no alphanumeric rune, the rightmost rune will be increased by 1
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// regardless whether the result is a valid rune or not.
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//
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// Only following characters are alphanumeric.
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// - a - z
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// - A - Z
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// - 0 - 9
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//
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// Samples (borrowed from ruby's String#succ document):
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//
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// "abcd" => "abce"
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// "THX1138" => "THX1139"
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// "<<koala>>" => "<<koalb>>"
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// "1999zzz" => "2000aaa"
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// "ZZZ9999" => "AAAA0000"
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// "***" => "**+"
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func Successor(str string) string {
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if str == "" {
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return str
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}
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var r rune
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var i int
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carry := ' '
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runes := []rune(str)
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l := len(runes)
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lastAlphanumeric := l
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for i = l - 1; i >= 0; i-- {
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r = runes[i]
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if ('a' <= r && r <= 'y') ||
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('A' <= r && r <= 'Y') ||
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('0' <= r && r <= '8') {
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runes[i]++
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carry = ' '
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lastAlphanumeric = i
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break
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}
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switch r {
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case 'z':
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runes[i] = 'a'
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carry = 'a'
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lastAlphanumeric = i
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case 'Z':
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runes[i] = 'A'
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carry = 'A'
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lastAlphanumeric = i
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case '9':
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runes[i] = '0'
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carry = '0'
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lastAlphanumeric = i
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}
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}
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// Needs to add one character for carry.
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if i < 0 && carry != ' ' {
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buf := &stringBuilder{}
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buf.Grow(l + 4) // Reserve enough space for write.
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if lastAlphanumeric != 0 {
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buf.WriteString(str[:lastAlphanumeric])
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}
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buf.WriteRune(carry)
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for _, r = range runes[lastAlphanumeric:] {
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buf.WriteRune(r)
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}
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return buf.String()
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}
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// No alphanumeric character. Simply increase last rune's value.
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if lastAlphanumeric == l {
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runes[l-1]++
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}
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return string(runes)
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}
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