0
Fork 0
mirror of https://codeberg.org/forgejo/forgejo.git synced 2024-12-23 15:53:07 -05:00
forgejo/modules/charset/htmlstream.go
zeripath 99efa02edf
Switch Unicode Escaping to a VSCode-like system (#19990)
This PR rewrites the invisible unicode detection algorithm to more
closely match that of the Monaco editor on the system. It provides a
technique for detecting ambiguous characters and relaxes the detection
of combining marks.

Control characters are in addition detected as invisible in this
implementation whereas they are not on monaco but this is related to
font issues.

Close #19913

Signed-off-by: Andrew Thornton <art27@cantab.net>
2022-08-13 19:32:34 +01:00

201 lines
5.3 KiB
Go

// Copyright 2022 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package charset
import (
"fmt"
"io"
"golang.org/x/net/html"
)
// HTMLStreamer represents a SAX-like interface for HTML
type HTMLStreamer interface {
Error(err error) error
Doctype(data string) error
Comment(data string) error
StartTag(data string, attrs ...html.Attribute) error
SelfClosingTag(data string, attrs ...html.Attribute) error
EndTag(data string) error
Text(data string) error
}
// PassthroughHTMLStreamer is a passthrough streamer
type PassthroughHTMLStreamer struct {
next HTMLStreamer
}
func NewPassthroughStreamer(next HTMLStreamer) *PassthroughHTMLStreamer {
return &PassthroughHTMLStreamer{next: next}
}
var _ (HTMLStreamer) = &PassthroughHTMLStreamer{}
// Error tells the next streamer in line that there is an error
func (p *PassthroughHTMLStreamer) Error(err error) error {
return p.next.Error(err)
}
// Doctype tells the next streamer what the doctype is
func (p *PassthroughHTMLStreamer) Doctype(data string) error {
return p.next.Doctype(data)
}
// Comment tells the next streamer there is a comment
func (p *PassthroughHTMLStreamer) Comment(data string) error {
return p.next.Comment(data)
}
// StartTag tells the next streamer there is a starting tag
func (p *PassthroughHTMLStreamer) StartTag(data string, attrs ...html.Attribute) error {
return p.next.StartTag(data, attrs...)
}
// SelfClosingTag tells the next streamer there is a self-closing tag
func (p *PassthroughHTMLStreamer) SelfClosingTag(data string, attrs ...html.Attribute) error {
return p.next.SelfClosingTag(data, attrs...)
}
// EndTag tells the next streamer there is a end tag
func (p *PassthroughHTMLStreamer) EndTag(data string) error {
return p.next.EndTag(data)
}
// Text tells the next streamer there is a text
func (p *PassthroughHTMLStreamer) Text(data string) error {
return p.next.Text(data)
}
// HTMLStreamWriter acts as a writing sink
type HTMLStreamerWriter struct {
io.Writer
err error
}
// Write implements io.Writer
func (h *HTMLStreamerWriter) Write(data []byte) (int, error) {
if h.err != nil {
return 0, h.err
}
return h.Writer.Write(data)
}
// Write implements io.StringWriter
func (h *HTMLStreamerWriter) WriteString(data string) (int, error) {
if h.err != nil {
return 0, h.err
}
return h.Writer.Write([]byte(data))
}
// Error tells the next streamer in line that there is an error
func (h *HTMLStreamerWriter) Error(err error) error {
if h.err == nil {
h.err = err
}
return h.err
}
// Doctype tells the next streamer what the doctype is
func (h *HTMLStreamerWriter) Doctype(data string) error {
_, h.err = h.WriteString("<!DOCTYPE " + data + ">")
return h.err
}
// Comment tells the next streamer there is a comment
func (h *HTMLStreamerWriter) Comment(data string) error {
_, h.err = h.WriteString("<!--" + data + "-->")
return h.err
}
// StartTag tells the next streamer there is a starting tag
func (h *HTMLStreamerWriter) StartTag(data string, attrs ...html.Attribute) error {
return h.startTag(data, attrs, false)
}
// SelfClosingTag tells the next streamer there is a self-closing tag
func (h *HTMLStreamerWriter) SelfClosingTag(data string, attrs ...html.Attribute) error {
return h.startTag(data, attrs, true)
}
func (h *HTMLStreamerWriter) startTag(data string, attrs []html.Attribute, selfclosing bool) error {
if _, h.err = h.WriteString("<" + data); h.err != nil {
return h.err
}
for _, attr := range attrs {
if _, h.err = h.WriteString(" " + attr.Key + "=\"" + html.EscapeString(attr.Val) + "\""); h.err != nil {
return h.err
}
}
if selfclosing {
if _, h.err = h.WriteString("/>"); h.err != nil {
return h.err
}
} else {
if _, h.err = h.WriteString(">"); h.err != nil {
return h.err
}
}
return h.err
}
// EndTag tells the next streamer there is a end tag
func (h *HTMLStreamerWriter) EndTag(data string) error {
_, h.err = h.WriteString("</" + data + ">")
return h.err
}
// Text tells the next streamer there is a text
func (h *HTMLStreamerWriter) Text(data string) error {
_, h.err = h.WriteString(html.EscapeString(data))
return h.err
}
// StreamHTML streams an html to a provided streamer
func StreamHTML(source io.Reader, streamer HTMLStreamer) error {
tokenizer := html.NewTokenizer(source)
for {
tt := tokenizer.Next()
switch tt {
case html.ErrorToken:
if tokenizer.Err() != io.EOF {
return tokenizer.Err()
}
return nil
case html.DoctypeToken:
token := tokenizer.Token()
if err := streamer.Doctype(token.Data); err != nil {
return err
}
case html.CommentToken:
token := tokenizer.Token()
if err := streamer.Comment(token.Data); err != nil {
return err
}
case html.StartTagToken:
token := tokenizer.Token()
if err := streamer.StartTag(token.Data, token.Attr...); err != nil {
return err
}
case html.SelfClosingTagToken:
token := tokenizer.Token()
if err := streamer.StartTag(token.Data, token.Attr...); err != nil {
return err
}
case html.EndTagToken:
token := tokenizer.Token()
if err := streamer.EndTag(token.Data); err != nil {
return err
}
case html.TextToken:
token := tokenizer.Token()
if err := streamer.Text(token.Data); err != nil {
return err
}
default:
return fmt.Errorf("unknown type of token: %d", tt)
}
}
}