Move filters to pkg/filters
Signed-off-by: Derek McGowan <derek@mcg.dev>
This commit is contained in:
Derek McGowan
252
pkg/filters/quote.go
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252
pkg/filters/quote.go
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@@ -0,0 +1,252 @@
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package filters
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import (
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"errors"
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"unicode/utf8"
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)
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// NOTE(stevvooe): Most of this code in this file is copied from the stdlib
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// strconv package and modified to be able to handle quoting with `/` and `|`
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// as delimiters. The copyright is held by the Go authors.
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var errQuoteSyntax = errors.New("quote syntax error")
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// UnquoteChar decodes the first character or byte in the escaped string
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// or character literal represented by the string s.
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// It returns four values:
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//
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// 1. value, the decoded Unicode code point or byte value;
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// 2. multibyte, a boolean indicating whether the decoded character requires a multibyte UTF-8 representation;
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// 3. tail, the remainder of the string after the character; and
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// 4. an error that will be nil if the character is syntactically valid.
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//
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// The second argument, quote, specifies the type of literal being parsed
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// and therefore which escaped quote character is permitted.
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// If set to a single quote, it permits the sequence \' and disallows unescaped '.
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// If set to a double quote, it permits \" and disallows unescaped ".
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// If set to zero, it does not permit either escape and allows both quote characters to appear unescaped.
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//
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// This is from Go strconv package, modified to support `|` and `/` as double
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// quotes for use with regular expressions.
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func unquoteChar(s string, quote byte) (value rune, multibyte bool, tail string, err error) {
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// easy cases
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switch c := s[0]; {
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case c == quote && (quote == '\'' || quote == '"' || quote == '/' || quote == '|'):
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err = errQuoteSyntax
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return
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case c >= utf8.RuneSelf:
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r, size := utf8.DecodeRuneInString(s)
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return r, true, s[size:], nil
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case c != '\\':
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return rune(s[0]), false, s[1:], nil
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}
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// hard case: c is backslash
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if len(s) <= 1 {
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err = errQuoteSyntax
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return
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}
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c := s[1]
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s = s[2:]
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switch c {
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case 'a':
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value = '\a'
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case 'b':
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value = '\b'
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case 'f':
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value = '\f'
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case 'n':
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value = '\n'
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case 'r':
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value = '\r'
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case 't':
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value = '\t'
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case 'v':
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value = '\v'
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case 'x', 'u', 'U':
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n := 0
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switch c {
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case 'x':
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n = 2
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case 'u':
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n = 4
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case 'U':
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n = 8
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}
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var v rune
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if len(s) < n {
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err = errQuoteSyntax
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return
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}
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for j := 0; j < n; j++ {
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x, ok := unhex(s[j])
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if !ok {
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err = errQuoteSyntax
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return
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}
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v = v<<4 | x
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}
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s = s[n:]
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if c == 'x' {
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// single-byte string, possibly not UTF-8
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value = v
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break
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}
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if v > utf8.MaxRune {
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err = errQuoteSyntax
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return
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}
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value = v
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multibyte = true
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case '0', '1', '2', '3', '4', '5', '6', '7':
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v := rune(c) - '0'
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if len(s) < 2 {
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err = errQuoteSyntax
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return
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}
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for j := 0; j < 2; j++ { // one digit already; two more
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x := rune(s[j]) - '0'
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if x < 0 || x > 7 {
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err = errQuoteSyntax
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return
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}
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v = (v << 3) | x
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}
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s = s[2:]
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if v > 255 {
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err = errQuoteSyntax
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return
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}
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value = v
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case '\\':
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value = '\\'
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case '\'', '"', '|', '/':
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if c != quote {
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err = errQuoteSyntax
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return
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}
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value = rune(c)
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default:
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err = errQuoteSyntax
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return
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}
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tail = s
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return
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}
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// unquote interprets s as a single-quoted, double-quoted,
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// or backquoted Go string literal, returning the string value
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// that s quotes. (If s is single-quoted, it would be a Go
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// character literal; Unquote returns the corresponding
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// one-character string.)
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//
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// This is modified from the standard library to support `|` and `/` as quote
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// characters for use with regular expressions.
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func unquote(s string) (string, error) {
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n := len(s)
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if n < 2 {
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return "", errQuoteSyntax
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}
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quote := s[0]
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if quote != s[n-1] {
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return "", errQuoteSyntax
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}
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s = s[1 : n-1]
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if quote == '`' {
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if contains(s, '`') {
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return "", errQuoteSyntax
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}
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if contains(s, '\r') {
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// -1 because we know there is at least one \r to remove.
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buf := make([]byte, 0, len(s)-1)
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for i := 0; i < len(s); i++ {
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if s[i] != '\r' {
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buf = append(buf, s[i])
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}
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}
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return string(buf), nil
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}
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return s, nil
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}
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if quote != '"' && quote != '\'' && quote != '|' && quote != '/' {
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return "", errQuoteSyntax
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}
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if contains(s, '\n') {
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return "", errQuoteSyntax
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}
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// Is it trivial? Avoid allocation.
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if !contains(s, '\\') && !contains(s, quote) {
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switch quote {
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case '"', '/', '|': // pipe and slash are treated like double quote
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return s, nil
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case '\'':
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r, size := utf8.DecodeRuneInString(s)
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if size == len(s) && (r != utf8.RuneError || size != 1) {
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return s, nil
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}
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}
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}
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var runeTmp [utf8.UTFMax]byte
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buf := make([]byte, 0, 3*len(s)/2) // Try to avoid more allocations.
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for len(s) > 0 {
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c, multibyte, ss, err := unquoteChar(s, quote)
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if err != nil {
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return "", err
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}
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s = ss
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if c < utf8.RuneSelf || !multibyte {
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buf = append(buf, byte(c))
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} else {
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n := utf8.EncodeRune(runeTmp[:], c)
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buf = append(buf, runeTmp[:n]...)
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}
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if quote == '\'' && len(s) != 0 {
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// single-quoted must be single character
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return "", errQuoteSyntax
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}
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}
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return string(buf), nil
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}
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// contains reports whether the string contains the byte c.
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func contains(s string, c byte) bool {
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for i := 0; i < len(s); i++ {
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if s[i] == c {
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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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func unhex(b byte) (v rune, ok bool) {
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c := rune(b)
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switch {
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case '0' <= c && c <= '9':
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return c - '0', true
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case 'a' <= c && c <= 'f':
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return c - 'a' + 10, true
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case 'A' <= c && c <= 'F':
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return c - 'A' + 10, true
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}
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return
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}
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