628 lines
16 KiB
Go
628 lines
16 KiB
Go
/*
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Translate file names for usage on restrictive storage systems
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The restricted set of characters are mapped to a unicode equivalent version
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(most to their FULLWIDTH variant) to increase compatability with other
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storage systems.
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See: http://unicode-search.net/unicode-namesearch.pl?term=FULLWIDTH
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Encoders will also quote reserved characters to differentiate between
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the raw and encoded forms.
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*/
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package encoder
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import (
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"bytes"
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"fmt"
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"io"
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"strconv"
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"strings"
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"unicode/utf8"
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)
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const (
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// adding this to any printable ASCII character turns it into the
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// FULLWIDTH variant
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fullOffset = 0xFEE0
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// the first rune of the SYMBOL FOR block for control characters
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symbolOffset = '␀' // SYMBOL FOR NULL
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// QuoteRune is the rune used for quoting reserved characters
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QuoteRune = '‛' // SINGLE HIGH-REVERSED-9 QUOTATION MARK
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)
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// Possible flags for the MultiEncoder
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const (
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EncodeZero uint = 0 // NUL(0x00)
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EncodeSlash uint = 1 << iota // /
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EncodeWin // :?"*<>|
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EncodeBackSlash // \
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EncodeHashPercent // #%
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EncodeDel // DEL(0x7F)
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EncodeCtl // CTRL(0x01-0x1F)
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EncodeLeftSpace // Leading SPACE
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EncodeLeftTilde // Leading ~
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EncodeLeftCrLfHtVt // Leading CR LF HT VT
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EncodeRightSpace // Trailing SPACE
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EncodeRightPeriod // Trailing .
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EncodeRightCrLfHtVt // Trailing CR LF HT VT
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EncodeInvalidUtf8 // Invalid UTF-8 bytes
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EncodeDot // . and .. names
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)
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// Encoder can transform names to and from the original and translated version.
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type Encoder interface {
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// Encode takes a raw name and substitutes any reserved characters and
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// patterns in it
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Encode(string) string
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// Decode takes a name and undoes any substitutions made by Encode
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Decode(string) string
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// FromStandardPath takes a / separated path in Standard encoding
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// and converts it to a / separated path in this encoding.
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FromStandardPath(string) string
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// FromStandardName takes name in Standard encoding and converts
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// it in this encoding.
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FromStandardName(string) string
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// ToStandardPath takes a / separated path in this encoding
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// and converts it to a / separated path in Standard encoding.
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ToStandardPath(string) string
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// ToStandardName takes name in this encoding and converts
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// it in Standard encoding.
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ToStandardName(string) string
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}
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// MultiEncoder is a configurable Encoder. The Encode* constants in this
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// package can be combined using bitwise or (|) to enable handling of multiple
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// character classes
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type MultiEncoder uint
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// Encode takes a raw name and substitutes any reserved characters and
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// patterns in it
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func (mask MultiEncoder) Encode(in string) string {
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var (
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encodeWin = uint(mask)&EncodeWin != 0
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encodeSlash = uint(mask)&EncodeSlash != 0
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encodeBackSlash = uint(mask)&EncodeBackSlash != 0
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encodeHashPercent = uint(mask)&EncodeHashPercent != 0
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encodeDel = uint(mask)&EncodeDel != 0
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encodeCtl = uint(mask)&EncodeCtl != 0
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encodeLeftSpace = uint(mask)&EncodeLeftSpace != 0
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encodeLeftTilde = uint(mask)&EncodeLeftTilde != 0
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encodeRightSpace = uint(mask)&EncodeRightSpace != 0
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encodeRightPeriod = uint(mask)&EncodeRightPeriod != 0
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encodeInvalidUnicode = uint(mask)&EncodeInvalidUtf8 != 0
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)
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// handle prefix only replacements
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prefix := ""
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if encodeLeftSpace && len(in) > 0 { // Leading SPACE
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if in[0] == ' ' {
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prefix, in = "␠", in[1:] // SYMBOL FOR SPACE
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} else if r, l := utf8.DecodeRuneInString(in); r == '␠' { // SYMBOL FOR SPACE
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prefix, in = string(QuoteRune)+"␠", in[l:] // SYMBOL FOR SPACE
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}
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}
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if encodeLeftTilde && len(in) > 0 { // Leading ~
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if in[0] == '~' {
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prefix, in = string('~'+fullOffset), in[1:] // FULLWIDTH TILDE
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} else if r, l := utf8.DecodeRuneInString(in); r == '~'+fullOffset {
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prefix, in = string(QuoteRune)+string('~'+fullOffset), in[l:] // FULLWIDTH TILDE
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}
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}
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// handle suffix only replacements
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suffix := ""
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if encodeRightSpace && len(in) > 0 { // Trailing SPACE
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if in[len(in)-1] == ' ' {
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suffix, in = "␠", in[:len(in)-1] // SYMBOL FOR SPACE
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} else if r, l := utf8.DecodeLastRuneInString(in); r == '␠' {
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suffix, in = string(QuoteRune)+"␠", in[:len(in)-l] // SYMBOL FOR SPACE
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}
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}
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if encodeRightPeriod && len(in) > 0 { // Trailing .
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if in[len(in)-1] == '.' {
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suffix, in = "．", in[:len(in)-1] // FULLWIDTH FULL STOP
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} else if r, l := utf8.DecodeLastRuneInString(in); r == '．' {
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suffix, in = string(QuoteRune)+"．", in[:len(in)-l] // FULLWIDTH FULL STOP
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}
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}
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index := 0
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if prefix == "" && suffix == "" {
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// find the first rune which (most likely) needs to be replaced
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index = strings.IndexFunc(in, func(r rune) bool {
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switch r {
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case 0, '␀', QuoteRune, utf8.RuneError:
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return true
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}
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if encodeWin { // :?"*<>|
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switch r {
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case '*', '<', '>', '?', ':', '|', '"',
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'＊', '＜', '＞', '？', '：', '｜', '＂':
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return true
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}
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}
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if encodeSlash { // /
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switch r {
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case '/',
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'／':
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return true
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}
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}
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if encodeBackSlash { // \
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switch r {
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case '\\',
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'＼':
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return true
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}
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}
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if encodeHashPercent { // #%
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switch r {
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case '#', '%',
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'＃', '％':
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return true
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}
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}
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if encodeDel { // DEL(0x7F)
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switch r {
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case rune(0x7F), '␡':
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return true
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}
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}
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if encodeCtl { // CTRL(0x01-0x1F)
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if r >= 1 && r <= 0x1F {
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return true
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} else if r > symbolOffset && r <= symbolOffset+0x1F {
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return true
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}
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}
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return false
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})
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}
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// nothing to replace, return input
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if index == -1 {
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return in
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}
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var out bytes.Buffer
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out.Grow(len(in) + len(prefix) + len(suffix))
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out.WriteString(prefix)
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// copy the clean part of the input and skip it
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out.WriteString(in[:index])
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in = in[index:]
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for i, r := range in {
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switch r {
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case 0:
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out.WriteRune(symbolOffset)
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continue
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case '␀', QuoteRune:
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out.WriteRune(QuoteRune)
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out.WriteRune(r)
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continue
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case utf8.RuneError:
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if encodeInvalidUnicode {
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// only encode invalid sequences and not utf8.RuneError
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if i+3 > len(in) || in[i:i+3] != string(utf8.RuneError) {
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_, l := utf8.DecodeRuneInString(in[i:])
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appendQuotedBytes(&out, in[i:i+l])
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continue
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}
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} else {
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// append the real bytes instead of utf8.RuneError
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_, l := utf8.DecodeRuneInString(in[i:])
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out.WriteString(in[i : i+l])
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continue
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}
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}
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if encodeWin { // :?"*<>|
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switch r {
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case '*', '<', '>', '?', ':', '|', '"':
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out.WriteRune(r + fullOffset)
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continue
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case '＊', '＜', '＞', '？', '：', '｜', '＂':
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out.WriteRune(QuoteRune)
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out.WriteRune(r)
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continue
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}
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}
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if encodeSlash { // /
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switch r {
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case '/':
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out.WriteRune(r + fullOffset)
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continue
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case '／':
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out.WriteRune(QuoteRune)
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out.WriteRune(r)
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continue
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}
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}
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if encodeBackSlash { // \
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switch r {
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case '\\':
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out.WriteRune(r + fullOffset)
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continue
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case '＼':
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out.WriteRune(QuoteRune)
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out.WriteRune(r)
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continue
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}
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}
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if encodeHashPercent { // #%
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switch r {
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case '#', '%':
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out.WriteRune(r + fullOffset)
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continue
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case '＃', '％':
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out.WriteRune(QuoteRune)
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out.WriteRune(r)
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continue
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}
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}
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if encodeDel { // DEL(0x7F)
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switch r {
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case rune(0x7F):
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out.WriteRune('␡') // SYMBOL FOR DELETE
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continue
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case '␡':
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out.WriteRune(QuoteRune)
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out.WriteRune(r)
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continue
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}
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}
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if encodeCtl { // CTRL(0x01-0x1F)
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if r >= 1 && r <= 0x1F {
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out.WriteRune('␀' + r) // SYMBOL FOR NULL
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continue
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} else if r > symbolOffset && r <= symbolOffset+0x1F {
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out.WriteRune(QuoteRune)
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out.WriteRune(r)
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continue
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}
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}
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out.WriteRune(r)
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}
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out.WriteString(suffix)
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return out.String()
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}
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// Decode takes a name and undoes any substitutions made by Encode
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func (mask MultiEncoder) Decode(in string) string {
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var (
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encodeWin = uint(mask)&EncodeWin != 0
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encodeSlash = uint(mask)&EncodeSlash != 0
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encodeBackSlash = uint(mask)&EncodeBackSlash != 0
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encodeHashPercent = uint(mask)&EncodeHashPercent != 0
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encodeDel = uint(mask)&EncodeDel != 0
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encodeCtl = uint(mask)&EncodeCtl != 0
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encodeLeftSpace = uint(mask)&EncodeLeftSpace != 0
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encodeLeftTilde = uint(mask)&EncodeLeftTilde != 0
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encodeRightSpace = uint(mask)&EncodeRightSpace != 0
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encodeRightPeriod = uint(mask)&EncodeRightPeriod != 0
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encodeInvalidUnicode = uint(mask)&EncodeInvalidUtf8 != 0
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)
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// handle prefix only replacements
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prefix := ""
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if r, l1 := utf8.DecodeRuneInString(in); encodeLeftSpace && r == '␠' { // SYMBOL FOR SPACE
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prefix, in = " ", in[l1:]
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} else if encodeLeftTilde && r == '～' { // FULLWIDTH TILDE
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prefix, in = "~", in[l1:]
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} else if r == QuoteRune {
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if r, l2 := utf8.DecodeRuneInString(in[l1:]); encodeLeftSpace && r == '␠' { // SYMBOL FOR SPACE
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prefix, in = "␠", in[l1+l2:]
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} else if encodeLeftTilde && r == '～' { // FULLWIDTH TILDE
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prefix, in = "～", in[l1+l2:]
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}
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}
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// handle suffix only replacements
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suffix := ""
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if r, l := utf8.DecodeLastRuneInString(in); encodeRightSpace && r == '␠' { // SYMBOL FOR SPACE
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in = in[:len(in)-l]
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if r, l2 := utf8.DecodeLastRuneInString(in); r == QuoteRune {
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suffix, in = "␠", in[:len(in)-l2]
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} else {
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suffix = " "
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}
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} else if encodeRightPeriod && r == '．' { // FULLWIDTH FULL STOP
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in = in[:len(in)-l]
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if r, l2 := utf8.DecodeLastRuneInString(in); r == QuoteRune {
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suffix, in = "．", in[:len(in)-l2]
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} else {
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suffix = "."
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}
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}
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index := 0
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if prefix == "" && suffix == "" {
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// find the first rune which (most likely) needs to be replaced
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index = strings.IndexFunc(in, func(r rune) bool {
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switch r {
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case '␀', QuoteRune:
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return true
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}
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if encodeWin { // :?"*<>|
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switch r {
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case '＊', '＜', '＞', '？', '：', '｜', '＂':
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return true
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}
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}
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if encodeSlash { // /
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switch r {
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case '／':
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return true
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}
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}
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if encodeBackSlash { // \
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switch r {
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case '＼':
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return true
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}
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}
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if encodeHashPercent { // #%
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switch r {
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case '＃', '％':
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return true
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}
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}
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if encodeDel { // DEL(0x7F)
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switch r {
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case '␡':
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return true
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}
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}
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if encodeCtl { // CTRL(0x01-0x1F)
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if r > symbolOffset && r <= symbolOffset+0x1F {
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return true
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}
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}
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return false
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})
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}
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// nothing to replace, return input
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if index == -1 {
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return in
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}
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var out bytes.Buffer
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out.Grow(len(in))
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out.WriteString(prefix)
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// copy the clean part of the input and skip it
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out.WriteString(in[:index])
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in = in[index:]
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var unquote, unquoteNext, skipNext bool
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for i, r := range in {
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if skipNext {
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skipNext = false
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continue
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}
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unquote, unquoteNext = unquoteNext, false
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switch r {
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case '␀': // SYMBOL FOR NULL
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if unquote {
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out.WriteRune(r)
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} else {
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out.WriteRune(0)
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}
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continue
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case QuoteRune:
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if unquote {
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out.WriteRune(r)
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} else {
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unquoteNext = true
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}
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continue
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}
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if encodeWin { // :?"*<>|
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switch r {
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case '＊', '＜', '＞', '？', '：', '｜', '＂':
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if unquote {
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out.WriteRune(r)
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} else {
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out.WriteRune(r - fullOffset)
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}
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continue
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}
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}
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if encodeSlash { // /
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switch r {
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case '／': // FULLWIDTH SOLIDUS
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if unquote {
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out.WriteRune(r)
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} else {
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out.WriteRune(r - fullOffset)
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}
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continue
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}
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}
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if encodeBackSlash { // \
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switch r {
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case '＼': // FULLWIDTH REVERSE SOLIDUS
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if unquote {
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out.WriteRune(r)
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} else {
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out.WriteRune(r - fullOffset)
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}
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continue
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}
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}
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if encodeHashPercent { // #%
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switch r {
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case '＃', '％':
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if unquote {
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out.WriteRune(r)
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} else {
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out.WriteRune(r - fullOffset)
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}
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continue
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}
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}
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if encodeDel { // DEL(0x7F)
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switch r {
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case '␡': // SYMBOL FOR DELETE
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if unquote {
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out.WriteRune(r)
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} else {
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out.WriteRune(0x7F)
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}
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continue
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}
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}
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if encodeCtl { // CTRL(0x01-0x1F)
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if r > symbolOffset && r <= symbolOffset+0x1F {
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if unquote {
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out.WriteRune(r)
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} else {
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out.WriteRune(r - symbolOffset)
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}
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continue
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}
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}
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if unquote {
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if encodeInvalidUnicode {
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skipNext = appendUnquotedByte(&out, in[i:])
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if skipNext {
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continue
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}
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}
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out.WriteRune(QuoteRune)
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}
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switch r {
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case utf8.RuneError:
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// append the real bytes instead of utf8.RuneError
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_, l := utf8.DecodeRuneInString(in[i:])
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out.WriteString(in[i : i+l])
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continue
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}
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out.WriteRune(r)
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}
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if unquoteNext {
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out.WriteRune(QuoteRune)
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}
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out.WriteString(suffix)
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return out.String()
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}
|
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|
|
// FromStandardPath takes a / separated path in Standard encoding
|
|
// and converts it to a / separated path in this encoding.
|
|
func (mask MultiEncoder) FromStandardPath(s string) string {
|
|
return FromStandardPath(mask, s)
|
|
}
|
|
|
|
// FromStandardName takes name in Standard encoding and converts
|
|
// it in this encoding.
|
|
func (mask MultiEncoder) FromStandardName(s string) string {
|
|
return FromStandardName(mask, s)
|
|
}
|
|
|
|
// ToStandardPath takes a / separated path in this encoding
|
|
// and converts it to a / separated path in Standard encoding.
|
|
func (mask MultiEncoder) ToStandardPath(s string) string {
|
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return ToStandardPath(mask, s)
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}
|
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|
|
// ToStandardName takes name in this encoding and converts
|
|
// it in Standard encoding.
|
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func (mask MultiEncoder) ToStandardName(s string) string {
|
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return ToStandardName(mask, s)
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}
|
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|
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func appendQuotedBytes(w io.Writer, s string) {
|
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for _, b := range []byte(s) {
|
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_, _ = fmt.Fprintf(w, string(QuoteRune)+"%02X", b)
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}
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}
|
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func appendUnquotedByte(w io.Writer, s string) bool {
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if len(s) < 2 {
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|
return false
|
|
}
|
|
u, err := strconv.ParseUint(s[:2], 16, 8)
|
|
if err != nil {
|
|
return false
|
|
}
|
|
n, _ := w.Write([]byte{byte(u)})
|
|
return n == 1
|
|
}
|
|
|
|
type identity struct{}
|
|
|
|
func (identity) Encode(in string) string { return in }
|
|
func (identity) Decode(in string) string { return in }
|
|
|
|
func (i identity) FromStandardPath(s string) string {
|
|
return FromStandardPath(i, s)
|
|
}
|
|
func (i identity) FromStandardName(s string) string {
|
|
return FromStandardName(i, s)
|
|
}
|
|
func (i identity) ToStandardPath(s string) string {
|
|
return ToStandardPath(i, s)
|
|
}
|
|
func (i identity) ToStandardName(s string) string {
|
|
return ToStandardName(i, s)
|
|
}
|
|
|
|
// Identity returns a Encoder that always returns the input value
|
|
func Identity() Encoder {
|
|
return identity{}
|
|
}
|
|
|
|
// FromStandardPath takes a / separated path in Standard encoding
|
|
// and converts it to a / separated path in the given encoding.
|
|
func FromStandardPath(e Encoder, s string) string {
|
|
if e == Standard {
|
|
return s
|
|
}
|
|
parts := strings.Split(s, "/")
|
|
encoded := make([]string, len(parts))
|
|
changed := false
|
|
for i, p := range parts {
|
|
enc := FromStandardName(e, p)
|
|
changed = changed || enc != p
|
|
encoded[i] = enc
|
|
}
|
|
if !changed {
|
|
return s
|
|
}
|
|
return strings.Join(encoded, "/")
|
|
}
|
|
|
|
// FromStandardName takes name in Standard encoding and converts
|
|
// it in the given encoding.
|
|
func FromStandardName(e Encoder, s string) string {
|
|
if e == Standard {
|
|
return s
|
|
}
|
|
return e.Encode(Standard.Decode(s))
|
|
}
|
|
|
|
// ToStandardPath takes a / separated path in the given encoding
|
|
// and converts it to a / separated path in Standard encoding.
|
|
func ToStandardPath(e Encoder, s string) string {
|
|
if e == Standard {
|
|
return s
|
|
}
|
|
parts := strings.Split(s, "/")
|
|
encoded := make([]string, len(parts))
|
|
changed := false
|
|
for i, p := range parts {
|
|
dec := ToStandardName(e, p)
|
|
changed = changed || dec != p
|
|
encoded[i] = dec
|
|
}
|
|
if !changed {
|
|
return s
|
|
}
|
|
return strings.Join(encoded, "/")
|
|
}
|
|
|
|
// ToStandardName takes name in the given encoding and converts
|
|
// it in Standard encoding.
|
|
func ToStandardName(e Encoder, s string) string {
|
|
if e == Standard {
|
|
return s
|
|
}
|
|
return Standard.Encode(e.Decode(s))
|
|
}
|