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// Copied and trimmed down from https://github.com/golang/go/blob/e3769299cd3484e018e0e2a6e1b95c2b18ce4f41/src/strconv/quote.go
// We want to use the standard library's private "quoteWith" function rather than write our own so that we get robust unicode support.
// Every private function called by quoteWith was copied.
// There are 2 modifications to simplify the code:
// 1. The unicode.IsPrint function was substituted for the custom implementation of IsPrint
// 2. All code paths reachable only when ASCIIonly or grphicOnly are set to true were removed.
// Copyright 2009 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 yaml
import (
"unicode"
"unicode/utf8"
)
const (
lowerhex = "0123456789abcdef"
)
func quoteWith(s string, quote byte) string {
return string(appendQuotedWith(make([]byte, 0, 3*len(s)/2), s, quote))
}
func appendQuotedWith(buf []byte, s string, quote byte) []byte {
// Often called with big strings, so preallocate. If there's quoting,
// this is conservative but still helps a lot.
if cap(buf)-len(buf) < len(s) {
nBuf := make([]byte, len(buf), len(buf)+1+len(s)+1)
copy(nBuf, buf)
buf = nBuf
}
buf = append(buf, quote)
for width := 0; len(s) > 0; s = s[width:] {
r := rune(s[0])
width = 1
if r >= utf8.RuneSelf {
r, width = utf8.DecodeRuneInString(s)
}
if width == 1 && r == utf8.RuneError {
buf = append(buf, `\x`...)
buf = append(buf, lowerhex[s[0]>>4])
buf = append(buf, lowerhex[s[0]&0xF])
continue
}
buf = appendEscapedRune(buf, r, quote)
}
buf = append(buf, quote)
return buf
}
func appendEscapedRune(buf []byte, r rune, quote byte) []byte {
var runeTmp [utf8.UTFMax]byte
if r == rune(quote) || r == '\\' { // always backslashed
buf = append(buf, '\\')
buf = append(buf, byte(r))
return buf
}
if unicode.IsPrint(r) {
n := utf8.EncodeRune(runeTmp[:], r)
buf = append(buf, runeTmp[:n]...)
return buf
}
switch r {
case '\a':
buf = append(buf, `\a`...)
case '\b':
buf = append(buf, `\b`...)
case '\f':
buf = append(buf, `\f`...)
case '\n':
buf = append(buf, `\n`...)
case '\r':
buf = append(buf, `\r`...)
case '\t':
buf = append(buf, `\t`...)
case '\v':
buf = append(buf, `\v`...)
default:
switch {
case r < ' ':
buf = append(buf, `\x`...)
buf = append(buf, lowerhex[byte(r)>>4])
buf = append(buf, lowerhex[byte(r)&0xF])
case r > utf8.MaxRune:
r = 0xFFFD
fallthrough
case r < 0x10000:
buf = append(buf, `\u`...)
for s := 12; s >= 0; s -= 4 {
buf = append(buf, lowerhex[r>>uint(s)&0xF])
}
default:
buf = append(buf, `\U`...)
for s := 28; s >= 0; s -= 4 {
buf = append(buf, lowerhex[r>>uint(s)&0xF])
}
}
}
return buf
}
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