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// gomuks - A terminal Matrix client written in Go.
// Copyright (C) 2018 Tulir Asokan
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package htmlparser
import (
"io"
"strings"
"golang.org/x/net/html"
)
type HTMLProcessor interface {
Preprocess()
HandleStartTag(tagName string, attrs map[string]string)
HandleSelfClosingTag(tagName string, attrs map[string]string)
HandleText(text string)
HandleEndTag(tagName string)
ReceiveError(err error)
Postprocess()
}
type HTMLParser struct {
*html.Tokenizer
processor HTMLProcessor
}
func NewHTMLParserFromTokenizer(z *html.Tokenizer, processor HTMLProcessor) HTMLParser {
return HTMLParser{
z,
processor,
}
}
func NewHTMLParserFromReader(reader io.Reader, processor HTMLProcessor) HTMLParser {
return NewHTMLParserFromTokenizer(html.NewTokenizer(reader), processor)
}
func NewHTMLParserFromString(html string, processor HTMLProcessor) HTMLParser {
return NewHTMLParserFromReader(strings.NewReader(html), processor)
}
var SelfClosingTags = []string{"img", "br", "hr", "area", "base", "basefont", "input", "link", "meta"}
func (parser HTMLParser) mapAttrs() map[string]string {
attrs := make(map[string]string)
hasMore := true
for hasMore {
var key, val []byte
key, val, hasMore = parser.TagAttr()
attrs[string(key)] = string(val)
}
return attrs
}
func (parser HTMLParser) isSelfClosing(tag string) bool {
for _, selfClosingTag := range SelfClosingTags {
if tag == selfClosingTag {
return true
}
}
return false
}
func (parser HTMLParser) Process() {
parser.processor.Preprocess()
Loop:
for {
tt := parser.Next()
switch tt {
case html.ErrorToken:
parser.processor.ReceiveError(parser.Err())
break Loop
case html.TextToken:
parser.processor.HandleText(string(parser.Text()))
case html.StartTagToken, html.SelfClosingTagToken:
tagb, _ := parser.TagName()
attrs := parser.mapAttrs()
tag := string(tagb)
selfClosing := tt == html.SelfClosingTagToken || parser.isSelfClosing(tag)
if selfClosing {
parser.processor.HandleSelfClosingTag(tag, attrs)
} else {
parser.processor.HandleStartTag(tag, attrs)
}
case html.EndTagToken:
tagb, _ := parser.TagName()
parser.processor.HandleEndTag(string(tagb))
}
}
parser.processor.Postprocess()
}
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