mirror of
https://github.com/superseriousbusiness/gotosocial.git
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542 lines
15 KiB
Go
542 lines
15 KiB
Go
// Package parse contains a collection of parsers for various formats in its subpackages.
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package parse
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import (
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"bytes"
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"encoding/base64"
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"errors"
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"strconv"
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)
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var (
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dataSchemeBytes = []byte("data:")
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base64Bytes = []byte("base64")
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textMimeBytes = []byte("text/plain")
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)
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// ErrBadDataURI is returned by DataURI when the byte slice does not start with 'data:' or is too short.
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var ErrBadDataURI = errors.New("not a data URI")
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// Number returns the number of bytes that parse as a number of the regex format (+|-)?([0-9]+(\.[0-9]+)?|\.[0-9]+)((e|E)(+|-)?[0-9]+)?.
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func Number(b []byte) int {
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if len(b) == 0 {
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return 0
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}
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i := 0
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if b[i] == '+' || b[i] == '-' {
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i++
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if i >= len(b) {
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return 0
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}
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}
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firstDigit := (b[i] >= '0' && b[i] <= '9')
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if firstDigit {
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i++
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for i < len(b) && b[i] >= '0' && b[i] <= '9' {
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i++
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}
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}
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if i < len(b) && b[i] == '.' {
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i++
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if i < len(b) && b[i] >= '0' && b[i] <= '9' {
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i++
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for i < len(b) && b[i] >= '0' && b[i] <= '9' {
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i++
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}
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} else if firstDigit {
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// . could belong to the next token
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i--
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return i
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} else {
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return 0
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}
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} else if !firstDigit {
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return 0
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}
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iOld := i
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if i < len(b) && (b[i] == 'e' || b[i] == 'E') {
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i++
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if i < len(b) && (b[i] == '+' || b[i] == '-') {
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i++
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}
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if i >= len(b) || b[i] < '0' || b[i] > '9' {
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// e could belong to next token
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return iOld
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}
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for i < len(b) && b[i] >= '0' && b[i] <= '9' {
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i++
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}
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}
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return i
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}
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// Dimension parses a byte-slice and returns the length of the number and its unit.
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func Dimension(b []byte) (int, int) {
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num := Number(b)
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if num == 0 || num == len(b) {
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return num, 0
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} else if b[num] == '%' {
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return num, 1
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} else if b[num] >= 'a' && b[num] <= 'z' || b[num] >= 'A' && b[num] <= 'Z' {
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i := num + 1
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for i < len(b) && (b[i] >= 'a' && b[i] <= 'z' || b[i] >= 'A' && b[i] <= 'Z') {
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i++
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}
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return num, i - num
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}
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return num, 0
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}
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// Mediatype parses a given mediatype and splits the mimetype from the parameters.
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// It works similar to mime.ParseMediaType but is faster.
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func Mediatype(b []byte) ([]byte, map[string]string) {
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i := 0
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for i < len(b) && b[i] == ' ' {
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i++
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}
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b = b[i:]
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n := len(b)
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mimetype := b
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var params map[string]string
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for i := 3; i < n; i++ { // mimetype is at least three characters long
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if b[i] == ';' || b[i] == ' ' {
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mimetype = b[:i]
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if b[i] == ' ' {
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i++ // space
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for i < n && b[i] == ' ' {
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i++
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}
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if n <= i || b[i] != ';' {
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break
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}
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}
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params = map[string]string{}
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s := string(b)
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PARAM:
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i++ // semicolon
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for i < n && s[i] == ' ' {
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i++
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}
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start := i
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for i < n && s[i] != '=' && s[i] != ';' && s[i] != ' ' {
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i++
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}
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key := s[start:i]
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for i < n && s[i] == ' ' {
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i++
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}
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if i < n && s[i] == '=' {
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i++
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for i < n && s[i] == ' ' {
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i++
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}
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start = i
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for i < n && s[i] != ';' && s[i] != ' ' {
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i++
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}
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} else {
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start = i
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}
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params[key] = s[start:i]
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for i < n && s[i] == ' ' {
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i++
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}
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if i < n && s[i] == ';' {
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goto PARAM
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}
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break
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}
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}
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return mimetype, params
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}
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// DataURI parses the given data URI and returns the mediatype, data and ok.
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func DataURI(dataURI []byte) ([]byte, []byte, error) {
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if len(dataURI) > 5 && bytes.Equal(dataURI[:5], dataSchemeBytes) {
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dataURI = dataURI[5:]
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inBase64 := false
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var mediatype []byte
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i := 0
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for j := 0; j < len(dataURI); j++ {
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c := dataURI[j]
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if c == '=' || c == ';' || c == ',' {
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if c != '=' && bytes.Equal(TrimWhitespace(dataURI[i:j]), base64Bytes) {
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if len(mediatype) > 0 {
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mediatype = mediatype[:len(mediatype)-1]
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}
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inBase64 = true
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i = j
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} else if c != ',' {
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mediatype = append(append(mediatype, TrimWhitespace(dataURI[i:j])...), c)
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i = j + 1
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} else {
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mediatype = append(mediatype, TrimWhitespace(dataURI[i:j])...)
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}
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if c == ',' {
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if len(mediatype) == 0 || mediatype[0] == ';' {
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mediatype = textMimeBytes
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}
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data := dataURI[j+1:]
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if inBase64 {
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decoded := make([]byte, base64.StdEncoding.DecodedLen(len(data)))
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n, err := base64.StdEncoding.Decode(decoded, data)
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if err != nil {
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return nil, nil, err
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}
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data = decoded[:n]
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} else {
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data = DecodeURL(data)
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}
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return mediatype, data, nil
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}
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}
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}
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}
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return nil, nil, ErrBadDataURI
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}
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// QuoteEntity parses the given byte slice and returns the quote that got matched (' or ") and its entity length.
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// TODO: deprecated
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func QuoteEntity(b []byte) (quote byte, n int) {
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if len(b) < 5 || b[0] != '&' {
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return 0, 0
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}
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if b[1] == '#' {
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if b[2] == 'x' {
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i := 3
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for i < len(b) && b[i] == '0' {
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i++
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}
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if i+2 < len(b) && b[i] == '2' && b[i+2] == ';' {
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if b[i+1] == '2' {
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return '"', i + 3 // "
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} else if b[i+1] == '7' {
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return '\'', i + 3 // '
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}
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}
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} else {
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i := 2
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for i < len(b) && b[i] == '0' {
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i++
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}
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if i+2 < len(b) && b[i] == '3' && b[i+2] == ';' {
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if b[i+1] == '4' {
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return '"', i + 3 // "
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} else if b[i+1] == '9' {
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return '\'', i + 3 // '
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}
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}
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}
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} else if len(b) >= 6 && b[5] == ';' {
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if bytes.Equal(b[1:5], []byte{'q', 'u', 'o', 't'}) {
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return '"', 6 // "
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} else if bytes.Equal(b[1:5], []byte{'a', 'p', 'o', 's'}) {
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return '\'', 6 // '
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}
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}
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return 0, 0
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}
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// ReplaceMultipleWhitespace replaces character series of space, \n, \t, \f, \r into a single space or newline (when the serie contained a \n or \r).
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func ReplaceMultipleWhitespace(b []byte) []byte {
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j, k := 0, 0 // j is write position, k is start of next text section
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for i := 0; i < len(b); i++ {
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if IsWhitespace(b[i]) {
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start := i
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newline := IsNewline(b[i])
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i++
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for ; i < len(b) && IsWhitespace(b[i]); i++ {
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if IsNewline(b[i]) {
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newline = true
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}
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}
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if newline {
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b[start] = '\n'
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} else {
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b[start] = ' '
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}
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if 1 < i-start { // more than one whitespace
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if j == 0 {
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j = start + 1
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} else {
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j += copy(b[j:], b[k:start+1])
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}
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k = i
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}
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}
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}
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if j == 0 {
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return b
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} else if j == 1 { // only if starts with whitespace
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b[k-1] = b[0]
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return b[k-1:]
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} else if k < len(b) {
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j += copy(b[j:], b[k:])
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}
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return b[:j]
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}
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// replaceEntities will replace in b at index i, assuming that b[i] == '&' and that i+3<len(b). The returned int will be the last character of the entity, so that the next iteration can safely do i++ to continue and not miss any entitites.
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func replaceEntities(b []byte, i int, entitiesMap map[string][]byte, revEntitiesMap map[byte][]byte) ([]byte, int) {
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const MaxEntityLength = 31 // longest HTML entity: CounterClockwiseContourIntegral
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var r []byte
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j := i + 1
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if b[j] == '#' {
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j++
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if b[j] == 'x' {
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j++
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c := 0
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for ; j < len(b) && (b[j] >= '0' && b[j] <= '9' || b[j] >= 'a' && b[j] <= 'f' || b[j] >= 'A' && b[j] <= 'F'); j++ {
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if b[j] <= '9' {
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c = c<<4 + int(b[j]-'0')
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} else if b[j] <= 'F' {
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c = c<<4 + int(b[j]-'A') + 10
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} else if b[j] <= 'f' {
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c = c<<4 + int(b[j]-'a') + 10
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}
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}
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if j <= i+3 || 10000 <= c {
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return b, j - 1
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}
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if c < 128 {
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r = []byte{byte(c)}
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} else {
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r = append(r, '&', '#')
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r = strconv.AppendInt(r, int64(c), 10)
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r = append(r, ';')
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}
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} else {
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c := 0
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for ; j < len(b) && c < 128 && b[j] >= '0' && b[j] <= '9'; j++ {
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c = c*10 + int(b[j]-'0')
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}
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if j <= i+2 || 128 <= c {
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return b, j - 1
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}
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r = []byte{byte(c)}
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}
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} else {
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for ; j < len(b) && j-i-1 <= MaxEntityLength && b[j] != ';'; j++ {
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}
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if j <= i+1 || len(b) <= j {
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return b, j - 1
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}
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var ok bool
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r, ok = entitiesMap[string(b[i+1:j])]
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if !ok {
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return b, j
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}
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}
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// j is at semicolon
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n := j + 1 - i
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if j < len(b) && b[j] == ';' && 2 < n {
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if len(r) == 1 {
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if q, ok := revEntitiesMap[r[0]]; ok {
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if len(q) == len(b[i:j+1]) && bytes.Equal(q, b[i:j+1]) {
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return b, j
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}
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r = q
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} else if r[0] == '&' {
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// check if for example & is followed by something that could potentially be an entity
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k := j + 1
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if k < len(b) && (b[k] >= '0' && b[k] <= '9' || b[k] >= 'a' && b[k] <= 'z' || b[k] >= 'A' && b[k] <= 'Z' || b[k] == '#') {
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return b, k
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}
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}
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}
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copy(b[i:], r)
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copy(b[i+len(r):], b[j+1:])
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b = b[:len(b)-n+len(r)]
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return b, i + len(r) - 1
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}
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return b, i
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}
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// ReplaceEntities replaces all occurrences of entites (such as ") to their respective unencoded bytes.
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func ReplaceEntities(b []byte, entitiesMap map[string][]byte, revEntitiesMap map[byte][]byte) []byte {
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for i := 0; i < len(b); i++ {
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if b[i] == '&' && i+3 < len(b) {
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b, i = replaceEntities(b, i, entitiesMap, revEntitiesMap)
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}
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}
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return b
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}
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// ReplaceMultipleWhitespaceAndEntities is a combination of ReplaceMultipleWhitespace and ReplaceEntities. It is faster than executing both sequentially.
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func ReplaceMultipleWhitespaceAndEntities(b []byte, entitiesMap map[string][]byte, revEntitiesMap map[byte][]byte) []byte {
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j, k := 0, 0 // j is write position, k is start of next text section
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for i := 0; i < len(b); i++ {
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if IsWhitespace(b[i]) {
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start := i
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newline := IsNewline(b[i])
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i++
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for ; i < len(b) && IsWhitespace(b[i]); i++ {
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if IsNewline(b[i]) {
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newline = true
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}
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}
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if newline {
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b[start] = '\n'
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} else {
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b[start] = ' '
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}
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if 1 < i-start { // more than one whitespace
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if j == 0 {
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j = start + 1
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} else {
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j += copy(b[j:], b[k:start+1])
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}
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k = i
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}
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}
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if i+3 < len(b) && b[i] == '&' {
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b, i = replaceEntities(b, i, entitiesMap, revEntitiesMap)
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}
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}
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if j == 0 {
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return b
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} else if j == 1 { // only if starts with whitespace
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b[k-1] = b[0]
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return b[k-1:]
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} else if k < len(b) {
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j += copy(b[j:], b[k:])
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}
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return b[:j]
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}
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// URLEncodingTable is a charmap for which characters need escaping in the URL encoding scheme
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var URLEncodingTable = [256]bool{
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// ASCII
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, false, true, true, true, true, true, false, // space, ", #, $, %, &
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false, false, false, true, true, false, false, true, // +, comma, /
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false, false, false, false, false, false, false, false,
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false, false, true, true, true, true, true, true, // :, ;, <, =, >, ?
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true, false, false, false, false, false, false, false, // @
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, true, true, true, true, false, // [, \, ], ^
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true, false, false, false, false, false, false, false, // `
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, true, true, true, false, true, // {, |, }, DEL
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// non-ASCII
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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}
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// DataURIEncodingTable is a charmap for which characters need escaping in the Data URI encoding scheme
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// Escape only non-printable characters, unicode and %, #, &.
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// IE11 additionally requires encoding of \, [, ], ", <, >, `, {, }, |, ^ which is not required by Chrome, Firefox, Opera, Edge, Safari, Yandex
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// To pass the HTML validator, restricted URL characters must be escaped: non-printable characters, space, <, >, #, %, "
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var DataURIEncodingTable = [256]bool{
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// ASCII
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, false, true, true, false, true, true, false, // space, ", #, %, &
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, true, false, true, false, // <, >
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, true, true, true, true, false, // [, \, ], ^
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|
|
true, false, false, false, false, false, false, false, // `
|
|
false, false, false, false, false, false, false, false,
|
|
false, false, false, false, false, false, false, false,
|
|
false, false, false, true, true, true, false, true, // {, |, }, DEL
|
|
|
|
// non-ASCII
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
true, true, true, true, true, true, true, true,
|
|
}
|
|
|
|
// EncodeURL encodes bytes using the URL encoding scheme
|
|
func EncodeURL(b []byte, table [256]bool) []byte {
|
|
for i := 0; i < len(b); i++ {
|
|
c := b[i]
|
|
if table[c] {
|
|
b = append(b, 0, 0)
|
|
copy(b[i+3:], b[i+1:])
|
|
b[i+0] = '%'
|
|
b[i+1] = "0123456789ABCDEF"[c>>4]
|
|
b[i+2] = "0123456789ABCDEF"[c&15]
|
|
}
|
|
}
|
|
return b
|
|
}
|
|
|
|
// DecodeURL decodes an URL encoded using the URL encoding scheme
|
|
func DecodeURL(b []byte) []byte {
|
|
for i := 0; i < len(b); i++ {
|
|
if b[i] == '%' && i+2 < len(b) {
|
|
j := i + 1
|
|
c := 0
|
|
for ; j < i+3 && (b[j] >= '0' && b[j] <= '9' || b[j] >= 'a' && b[j] <= 'f' || b[j] >= 'A' && b[j] <= 'F'); j++ {
|
|
if b[j] <= '9' {
|
|
c = c<<4 + int(b[j]-'0')
|
|
} else if b[j] <= 'F' {
|
|
c = c<<4 + int(b[j]-'A') + 10
|
|
} else if b[j] <= 'f' {
|
|
c = c<<4 + int(b[j]-'a') + 10
|
|
}
|
|
}
|
|
if j == i+3 && c < 128 {
|
|
b[i] = byte(c)
|
|
b = append(b[:i+1], b[i+3:]...)
|
|
}
|
|
} else if b[i] == '+' {
|
|
b[i] = ' '
|
|
}
|
|
}
|
|
return b
|
|
}
|