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matterbridge/vendor/gitlab.com/golang-commonmark/mdurl/encode.go

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// Copyright 2015 The 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 mdurl
import (
"bytes"
"strings"
"unicode/utf8"
)
// Encode percent-encodes rawurl, avoiding double encoding.
// It doesn't touch:
// - alphanumeric characters ([0-9a-zA-Z]);
// - percent-encoded characters (%[0-9a-fA-F]{2});
// - excluded characters ([;/?:@&=+$,-_.!~*'()#]).
// Invalid UTF-8 sequences are replaced with U+FFFD.
func Encode(rawurl string) string {
const hexdigit = "0123456789ABCDEF"
var buf bytes.Buffer
i := 0
for i < len(rawurl) {
r, rlen := utf8.DecodeRuneInString(rawurl[i:])
if r >= 0x80 {
for j, n := i, i+rlen; j < n; j++ {
b := rawurl[j]
buf.WriteByte('%')
buf.WriteByte(hexdigit[(b>>4)&0xf])
buf.WriteByte(hexdigit[b&0xf])
}
} else if r == '%' {
if i+2 < len(rawurl) &&
hexDigit(rawurl[i+1]) &&
hexDigit(rawurl[i+2]) {
buf.WriteByte('%')
buf.WriteByte(byteToUpper(rawurl[i+1]))
buf.WriteByte(byteToUpper(rawurl[i+2]))
i += 2
} else {
buf.WriteString("%25")
}
} else if strings.IndexByte("!#$&'()*+,-./0123456789:;=?@ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz~", byte(r)) == -1 {
buf.WriteByte('%')
buf.WriteByte(hexdigit[(r>>4)&0xf])
buf.WriteByte(hexdigit[r&0xf])
} else {
buf.WriteByte(byte(r))
}
i += rlen
}
return buf.String()
}