mirror of
https://github.com/chatmail/core.git
synced 2026-04-17 21:46:35 +03:00
292 lines
8.7 KiB
Rust
292 lines
8.7 KiB
Rust
//! De-HTML
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//!
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//! A module to remove HTML tags from the email text
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use once_cell::sync::Lazy;
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use quick_xml::events::{BytesEnd, BytesStart, BytesText};
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static LINE_RE: Lazy<regex::Regex> = Lazy::new(|| regex::Regex::new(r"(\r?\n)+").unwrap());
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struct Dehtml {
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strbuilder: String,
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add_text: AddText,
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last_href: Option<String>,
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}
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#[derive(Debug, PartialEq)]
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enum AddText {
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No,
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YesRemoveLineEnds,
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YesPreserveLineEnds,
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}
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/// dehtml() returns way too many newlines; however, an optimisation on this issue is not needed as
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/// the newlines are typically removed in further processing by the caller
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pub fn dehtml(buf: &str) -> Option<String> {
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let s = dehtml_quick_xml(buf);
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if !s.trim().is_empty() {
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return Some(s);
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}
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let s = dehtml_manually(buf);
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if !s.trim().is_empty() {
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return Some(s);
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}
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None
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}
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pub fn dehtml_quick_xml(buf: &str) -> String {
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let buf = buf.trim().trim_start_matches("<!doctype html>");
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let mut dehtml = Dehtml {
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strbuilder: String::with_capacity(buf.len()),
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add_text: AddText::YesRemoveLineEnds,
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last_href: None,
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};
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let mut reader = quick_xml::Reader::from_str(buf);
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reader.check_end_names(false);
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let mut buf = Vec::new();
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loop {
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match reader.read_event(&mut buf) {
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Ok(quick_xml::events::Event::Start(ref e)) => {
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dehtml_starttag_cb(e, &mut dehtml, &reader)
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}
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Ok(quick_xml::events::Event::End(ref e)) => dehtml_endtag_cb(e, &mut dehtml),
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Ok(quick_xml::events::Event::Text(ref e)) => dehtml_text_cb(e, &mut dehtml),
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Ok(quick_xml::events::Event::CData(ref e)) => dehtml_cdata_cb(e, &mut dehtml),
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Ok(quick_xml::events::Event::Empty(ref e)) => {
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// Handle empty tags as a start tag immediately followed by end tag.
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// For example, `<p/>` is treated as `<p></p>`.
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dehtml_starttag_cb(e, &mut dehtml, &reader);
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dehtml_endtag_cb(&BytesEnd::borrowed(e.name()), &mut dehtml);
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}
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Err(e) => {
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eprintln!(
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"Parse html error: Error at position {}: {:?}",
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reader.buffer_position(),
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e
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);
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}
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Ok(quick_xml::events::Event::Eof) => break,
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_ => (),
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}
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buf.clear();
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}
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dehtml.strbuilder
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}
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fn dehtml_text_cb(event: &BytesText, dehtml: &mut Dehtml) {
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if dehtml.add_text == AddText::YesPreserveLineEnds
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|| dehtml.add_text == AddText::YesRemoveLineEnds
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{
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let last_added = escaper::decode_html_buf_sloppy(event.escaped()).unwrap_or_default();
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if dehtml.add_text == AddText::YesRemoveLineEnds {
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dehtml.strbuilder += LINE_RE.replace_all(&last_added, "\r").as_ref();
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} else {
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dehtml.strbuilder += &last_added;
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}
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}
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}
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fn dehtml_cdata_cb(event: &BytesText, dehtml: &mut Dehtml) {
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if dehtml.add_text == AddText::YesPreserveLineEnds
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|| dehtml.add_text == AddText::YesRemoveLineEnds
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{
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let last_added = escaper::decode_html_buf_sloppy(event.escaped()).unwrap_or_default();
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if dehtml.add_text == AddText::YesRemoveLineEnds {
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dehtml.strbuilder += LINE_RE.replace_all(&last_added, "\r").as_ref();
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} else {
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dehtml.strbuilder += &last_added;
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}
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}
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}
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fn dehtml_endtag_cb(event: &BytesEnd, dehtml: &mut Dehtml) {
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let tag = String::from_utf8_lossy(event.name()).trim().to_lowercase();
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match tag.as_str() {
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"p" | "div" | "table" | "td" | "style" | "script" | "title" | "pre" => {
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dehtml.strbuilder += "\n\n";
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dehtml.add_text = AddText::YesRemoveLineEnds;
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}
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"a" => {
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if let Some(ref last_href) = dehtml.last_href.take() {
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dehtml.strbuilder += "](";
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dehtml.strbuilder += last_href;
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dehtml.strbuilder += ")";
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}
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}
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"b" | "strong" => {
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dehtml.strbuilder += "*";
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}
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"i" | "em" => {
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dehtml.strbuilder += "_";
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}
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_ => {}
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}
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}
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fn dehtml_starttag_cb<B: std::io::BufRead>(
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event: &BytesStart,
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dehtml: &mut Dehtml,
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reader: &quick_xml::Reader<B>,
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) {
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let tag = String::from_utf8_lossy(event.name()).trim().to_lowercase();
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match tag.as_str() {
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"p" | "div" | "table" | "td" => {
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dehtml.strbuilder += "\n\n";
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dehtml.add_text = AddText::YesRemoveLineEnds;
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}
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"br" => {
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dehtml.strbuilder += "\n";
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dehtml.add_text = AddText::YesRemoveLineEnds;
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}
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"style" | "script" | "title" => {
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dehtml.add_text = AddText::No;
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}
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"pre" => {
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dehtml.strbuilder += "\n\n";
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dehtml.add_text = AddText::YesPreserveLineEnds;
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}
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"a" => {
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if let Some(href) = event
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.html_attributes()
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.filter_map(|attr| attr.ok())
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.find(|attr| String::from_utf8_lossy(attr.key).trim().to_lowercase() == "href")
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{
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let href = href
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.unescape_and_decode_value(reader)
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.unwrap_or_default()
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.to_lowercase();
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if !href.is_empty() {
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dehtml.last_href = Some(href);
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dehtml.strbuilder += "[";
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}
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}
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}
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"b" | "strong" => {
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dehtml.strbuilder += "*";
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}
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"i" | "em" => {
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dehtml.strbuilder += "_";
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}
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_ => {}
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}
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}
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pub fn dehtml_manually(buf: &str) -> String {
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// Just strip out everything between "<" and ">"
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let mut strbuilder = String::new();
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let mut show_next_chars = true;
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for c in buf.chars() {
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match c {
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'<' => show_next_chars = false,
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'>' => show_next_chars = true,
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_ => {
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if show_next_chars {
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strbuilder.push(c)
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}
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}
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}
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}
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strbuilder
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::simplify::simplify;
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#[test]
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fn test_dehtml() {
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let cases = vec",
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),
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("<b> bar </b>", "* bar *"),
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("<b> bar <i> foo", "* bar _ foo"),
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("& bar", "& bar"),
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// Despite missing ', this should be shown:
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("<a href='/foo.png>Hi</a> ", "Hi "),
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(
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"<a href='https://get.delta.chat/'/>",
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"[](https://get.delta.chat/)",
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),
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("<!doctype html>\n<b>fat text</b>", "*fat text*"),
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// Invalid html (at least DC should show the text if the html is invalid):
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("<!some invalid html code>\n<b>some text</b>", "some text"),
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];
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for (input, output) in cases {
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assert_eq!(simplify(dehtml(input).unwrap(), true).0, output);
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}
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let none_cases = vec!["<html> </html>", ""];
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for input in none_cases {
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assert_eq!(dehtml(input), None);
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}
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}
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#[test]
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fn test_dehtml_parse_br() {
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let html = "\r\r\nline1<br>\r\n\r\n\r\rline2<br/>line3\n\r";
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let plain = dehtml(html).unwrap();
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assert_eq!(plain, "line1\n\r\r\rline2\nline3");
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}
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#[test]
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fn test_dehtml_parse_href() {
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let html = "<a href=url>text</a";
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let plain = dehtml(html).unwrap();
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assert_eq!(plain, "[text](url)");
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}
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#[test]
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fn test_dehtml_bold_text() {
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let html = "<!DOCTYPE name [<!DOCTYPE ...>]><!-- comment -->text <b><?php echo ... ?>bold</b><![CDATA[<>]]>";
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let plain = dehtml(html).unwrap();
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assert_eq!(plain, "text *bold*<>");
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}
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#[test]
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fn test_dehtml_html_encoded() {
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let html =
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"<>"'& äÄöÖüÜß fooÆçÇ ♦‎‏‌&noent;‍";
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let plain = dehtml(html).unwrap();
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assert_eq!(
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plain,
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"<>\"\'& äÄöÖüÜß fooÆçÇ \u{2666}\u{200e}\u{200f}\u{200c}&noent;\u{200d}"
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);
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}
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#[test]
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fn test_unclosed_tags() {
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let input = r##"
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<!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01 Transitional//EN'
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'http://www.w3.org/TR/html4/loose.dtd'>
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<html>
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<head>
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<title>Hi</title>
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<meta http-equiv='Content-Type' content='text/html; charset=iso-8859-1'>
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</head>
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<body>
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lots of text
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</body>
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</html>
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"##;
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let txt = dehtml(input).unwrap();
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assert_eq!(txt.trim(), "lots of text");
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}
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}
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