277 lines
5.1 KiB
Go
277 lines
5.1 KiB
Go
package logfmt
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import (
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"bytes"
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"io"
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"strconv"
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"sync"
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"unicode"
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"unicode/utf16"
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"unicode/utf8"
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)
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// Taken from Go's encoding/json and modified for use here.
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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var hex = "0123456789abcdef"
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var bufferPool = sync.Pool{
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New: func() interface{} {
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return &bytes.Buffer{}
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},
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}
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func getBuffer() *bytes.Buffer {
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return bufferPool.Get().(*bytes.Buffer)
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}
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func poolBuffer(buf *bytes.Buffer) {
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buf.Reset()
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bufferPool.Put(buf)
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}
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// NOTE: keep in sync with writeQuotedBytes below.
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func writeQuotedString(w io.Writer, s string) (int, error) {
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buf := getBuffer()
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buf.WriteByte('"')
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start := 0
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for i := 0; i < len(s); {
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if b := s[i]; b < utf8.RuneSelf {
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if 0x20 <= b && b != '\\' && b != '"' {
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i++
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continue
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}
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if start < i {
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buf.WriteString(s[start:i])
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}
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switch b {
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case '\\', '"':
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buf.WriteByte('\\')
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buf.WriteByte(b)
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case '\n':
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buf.WriteByte('\\')
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buf.WriteByte('n')
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case '\r':
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buf.WriteByte('\\')
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buf.WriteByte('r')
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case '\t':
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buf.WriteByte('\\')
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buf.WriteByte('t')
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default:
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// This encodes bytes < 0x20 except for \n, \r, and \t.
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buf.WriteString(`\u00`)
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buf.WriteByte(hex[b>>4])
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buf.WriteByte(hex[b&0xF])
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}
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i++
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start = i
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continue
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}
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c, size := utf8.DecodeRuneInString(s[i:])
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if c == utf8.RuneError {
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if start < i {
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buf.WriteString(s[start:i])
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}
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buf.WriteString(`\ufffd`)
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i += size
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start = i
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continue
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}
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i += size
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}
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if start < len(s) {
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buf.WriteString(s[start:])
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}
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buf.WriteByte('"')
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n, err := w.Write(buf.Bytes())
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poolBuffer(buf)
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return n, err
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}
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// NOTE: keep in sync with writeQuoteString above.
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func writeQuotedBytes(w io.Writer, s []byte) (int, error) {
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buf := getBuffer()
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buf.WriteByte('"')
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start := 0
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for i := 0; i < len(s); {
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if b := s[i]; b < utf8.RuneSelf {
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if 0x20 <= b && b != '\\' && b != '"' {
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i++
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continue
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}
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if start < i {
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buf.Write(s[start:i])
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}
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switch b {
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case '\\', '"':
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buf.WriteByte('\\')
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buf.WriteByte(b)
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case '\n':
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buf.WriteByte('\\')
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buf.WriteByte('n')
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case '\r':
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buf.WriteByte('\\')
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buf.WriteByte('r')
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case '\t':
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buf.WriteByte('\\')
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buf.WriteByte('t')
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default:
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// This encodes bytes < 0x20 except for \n, \r, and \t.
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buf.WriteString(`\u00`)
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buf.WriteByte(hex[b>>4])
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buf.WriteByte(hex[b&0xF])
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}
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i++
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start = i
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continue
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}
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c, size := utf8.DecodeRune(s[i:])
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if c == utf8.RuneError {
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if start < i {
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buf.Write(s[start:i])
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}
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buf.WriteString(`\ufffd`)
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i += size
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start = i
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continue
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}
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i += size
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}
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if start < len(s) {
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buf.Write(s[start:])
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}
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buf.WriteByte('"')
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n, err := w.Write(buf.Bytes())
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poolBuffer(buf)
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return n, err
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}
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// getu4 decodes \uXXXX from the beginning of s, returning the hex value,
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// or it returns -1.
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func getu4(s []byte) rune {
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if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
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return -1
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}
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r, err := strconv.ParseUint(string(s[2:6]), 16, 64)
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if err != nil {
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return -1
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}
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return rune(r)
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}
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func unquoteBytes(s []byte) (t []byte, ok bool) {
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if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
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return
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}
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s = s[1 : len(s)-1]
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// Check for unusual characters. If there are none,
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// then no unquoting is needed, so return a slice of the
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// original bytes.
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r := 0
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for r < len(s) {
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c := s[r]
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if c == '\\' || c == '"' || c < ' ' {
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break
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}
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if c < utf8.RuneSelf {
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r++
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continue
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}
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rr, size := utf8.DecodeRune(s[r:])
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if rr == utf8.RuneError {
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break
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}
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r += size
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}
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if r == len(s) {
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return s, true
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}
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b := make([]byte, len(s)+2*utf8.UTFMax)
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w := copy(b, s[0:r])
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for r < len(s) {
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// Out of room? Can only happen if s is full of
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// malformed UTF-8 and we're replacing each
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// byte with RuneError.
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if w >= len(b)-2*utf8.UTFMax {
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nb := make([]byte, (len(b)+utf8.UTFMax)*2)
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copy(nb, b[0:w])
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b = nb
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}
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switch c := s[r]; {
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case c == '\\':
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r++
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if r >= len(s) {
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return
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}
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switch s[r] {
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default:
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return
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case '"', '\\', '/', '\'':
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b[w] = s[r]
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r++
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w++
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case 'b':
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b[w] = '\b'
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r++
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w++
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case 'f':
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b[w] = '\f'
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r++
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w++
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case 'n':
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b[w] = '\n'
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r++
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w++
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case 'r':
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b[w] = '\r'
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r++
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w++
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case 't':
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b[w] = '\t'
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r++
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w++
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case 'u':
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r--
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rr := getu4(s[r:])
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if rr < 0 {
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return
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}
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r += 6
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if utf16.IsSurrogate(rr) {
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rr1 := getu4(s[r:])
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if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
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// A valid pair; consume.
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r += 6
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w += utf8.EncodeRune(b[w:], dec)
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break
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}
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// Invalid surrogate; fall back to replacement rune.
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rr = unicode.ReplacementChar
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}
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w += utf8.EncodeRune(b[w:], rr)
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}
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// Quote, control characters are invalid.
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case c == '"', c < ' ':
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return
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// ASCII
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case c < utf8.RuneSelf:
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b[w] = c
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r++
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w++
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// Coerce to well-formed UTF-8.
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default:
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rr, size := utf8.DecodeRune(s[r:])
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r += size
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w += utf8.EncodeRune(b[w:], rr)
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}
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}
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return b[0:w], true
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}
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