73 lines
2.0 KiB
Go
73 lines
2.0 KiB
Go
// Copyright 2015 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 precis
|
|
|
|
import (
|
|
"unicode"
|
|
"unicode/utf8"
|
|
|
|
"golang.org/x/text/transform"
|
|
)
|
|
|
|
type nickAdditionalMapping struct {
|
|
// TODO: This transformer needs to be stateless somehow…
|
|
notStart bool
|
|
prevSpace bool
|
|
}
|
|
|
|
func (t *nickAdditionalMapping) Reset() {
|
|
t.prevSpace = false
|
|
t.notStart = false
|
|
}
|
|
|
|
func (t *nickAdditionalMapping) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
|
|
// RFC 8266 §2.1. Rules
|
|
//
|
|
// 2. Additional Mapping Rule: The additional mapping rule consists of
|
|
// the following sub-rules.
|
|
//
|
|
// a. Map any instances of non-ASCII space to SPACE (U+0020); a
|
|
// non-ASCII space is any Unicode code point having a general
|
|
// category of "Zs", naturally with the exception of SPACE
|
|
// (U+0020). (The inclusion of only ASCII space prevents
|
|
// confusion with various non-ASCII space code points, many of
|
|
// which are difficult to reproduce across different input
|
|
// methods.)
|
|
//
|
|
// b. Remove any instances of the ASCII space character at the
|
|
// beginning or end of a nickname (e.g., "stpeter " is mapped to
|
|
// "stpeter").
|
|
//
|
|
// c. Map interior sequences of more than one ASCII space character
|
|
// to a single ASCII space character (e.g., "St Peter" is
|
|
// mapped to "St Peter").
|
|
for nSrc < len(src) {
|
|
r, size := utf8.DecodeRune(src[nSrc:])
|
|
if size == 0 { // Incomplete UTF-8 encoding
|
|
if !atEOF {
|
|
return nDst, nSrc, transform.ErrShortSrc
|
|
}
|
|
size = 1
|
|
}
|
|
if unicode.Is(unicode.Zs, r) {
|
|
t.prevSpace = true
|
|
} else {
|
|
if t.prevSpace && t.notStart {
|
|
dst[nDst] = ' '
|
|
nDst += 1
|
|
}
|
|
if size != copy(dst[nDst:], src[nSrc:nSrc+size]) {
|
|
nDst += size
|
|
return nDst, nSrc, transform.ErrShortDst
|
|
}
|
|
nDst += size
|
|
t.prevSpace = false
|
|
t.notStart = true
|
|
}
|
|
nSrc += size
|
|
}
|
|
return nDst, nSrc, nil
|
|
}
|