zola/components/rendering/src/markdown.rs
2017-10-23 14:18:05 +02:00

288 lines
12 KiB
Rust

use std::borrow::Cow::Owned;
use pulldown_cmark as cmark;
use self::cmark::{Parser, Event, Tag, Options, OPTION_ENABLE_TABLES, OPTION_ENABLE_FOOTNOTES};
use slug::slugify;
use syntect::easy::HighlightLines;
use syntect::html::{start_coloured_html_snippet, styles_to_coloured_html, IncludeBackground};
use errors::Result;
use utils::site::resolve_internal_link;
use context::Context;
use highlighting::{SYNTAX_SET, THEME_SET};
use short_code::{SHORTCODE_RE, ShortCode, parse_shortcode, render_simple_shortcode};
use table_of_contents::{TempHeader, Header, make_table_of_contents};
pub fn markdown_to_html(content: &str, context: &Context) -> Result<(String, Vec<Header>)> {
// We try to be smart about highlighting code as it can be time-consuming
// If the global config disables it, then we do nothing. However,
// if we see a code block in the content, we assume that this page needs
// to be highlighted. It could potentially have false positive if the content
// has ``` in it but that seems kind of unlikely
let should_highlight = if context.highlight_code {
content.contains("```")
} else {
false
};
// Set while parsing
let mut error = None;
let mut highlighter: Option<HighlightLines> = None;
// the markdown parser will send several Text event if a markdown character
// is present in it, for example `hello_test` will be split in 2: hello and _test.
// Since we can use those chars in shortcode arguments, we need to collect
// the full shortcode somehow first
let mut current_shortcode = String::new();
let mut shortcode_block = None;
// shortcodes live outside of paragraph so we need to ensure we don't close
// a paragraph that has already been closed
let mut added_shortcode = false;
// Don't transform things that look like shortcodes in code blocks
let mut in_code_block = false;
// If we get text in header, we need to insert the id and a anchor
let mut in_header = false;
// pulldown_cmark can send several text events for a title if there are markdown
// specific characters like `!` in them. We only want to insert the anchor the first time
let mut header_created = false;
let mut anchors: Vec<String> = vec![];
// the rendered html
let mut html = String::new();
// We might have cases where the slug is already present in our list of anchor
// for example an article could have several titles named Example
// We add a counter after the slug if the slug is already present, which
// means we will have example, example-1, example-2 etc
fn find_anchor(anchors: &[String], name: String, level: u8) -> String {
if level == 0 && !anchors.contains(&name) {
return name.to_string();
}
let new_anchor = format!("{}-{}", name, level + 1);
if !anchors.contains(&new_anchor) {
return new_anchor;
}
find_anchor(anchors, name, level + 1)
}
let mut headers = vec![];
// Defaults to a 0 level so not a real header
// It should be an Option ideally but not worth the hassle to update
let mut temp_header = TempHeader::default();
let mut opts = Options::empty();
opts.insert(OPTION_ENABLE_TABLES);
opts.insert(OPTION_ENABLE_FOOTNOTES);
{
let parser = Parser::new_ext(content, opts).map(|event| match event {
Event::Text(mut text) => {
// Header first
if in_header {
if header_created {
temp_header.push(&text);
return Event::Html(Owned(String::new()));
}
let id = find_anchor(&anchors, slugify(&text), 0);
anchors.push(id.clone());
// update the header and add it to the list
temp_header.id = id.clone();
// += as we might have some <code> or other things already there
temp_header.title += &text;
temp_header.permalink = format!("{}#{}", context.current_page_permalink, id);
header_created = true;
return Event::Html(Owned(String::new()));
}
// if we are in the middle of a code block
if let Some(ref mut highlighter) = highlighter {
let highlighted = &highlighter.highlight(&text);
let html = styles_to_coloured_html(highlighted, IncludeBackground::Yes);
return Event::Html(Owned(html));
}
if in_code_block {
return Event::Text(text);
}
// Are we in the middle of a shortcode that somehow got cut off
// by the markdown parser?
if current_shortcode.is_empty() {
if text.starts_with("{{") && !text.ends_with("}}") {
current_shortcode += &text;
} else if text.starts_with("{%") && !text.ends_with("%}") {
current_shortcode += &text;
}
} else {
current_shortcode += &text;
}
if current_shortcode.ends_with("}}") || current_shortcode.ends_with("%}") {
text = Owned(current_shortcode.clone());
current_shortcode = String::new();
}
// Shortcode without body
if shortcode_block.is_none() && text.starts_with("{{") && text.ends_with("}}") && SHORTCODE_RE.is_match(&text) {
let (name, args) = parse_shortcode(&text);
added_shortcode = true;
match render_simple_shortcode(context.tera, &name, &args) {
Ok(s) => return Event::Html(Owned(format!("</p>{}", s))),
Err(e) => {
error = Some(e);
return Event::Html(Owned(String::new()));
}
}
}
// Shortcode with a body
if shortcode_block.is_none() && text.starts_with("{%") && text.ends_with("%}") {
if SHORTCODE_RE.is_match(&text) {
let (name, args) = parse_shortcode(&text);
shortcode_block = Some(ShortCode::new(&name, args));
}
// Don't return anything
return Event::Text(Owned(String::new()));
}
// If we have some text while in a shortcode, it's either the body
// or the end tag
if shortcode_block.is_some() {
if let Some(ref mut shortcode) = shortcode_block {
if text.trim() == "{% end %}" {
added_shortcode = true;
match shortcode.render(context.tera) {
Ok(s) => return Event::Html(Owned(format!("</p>{}", s))),
Err(e) => {
error = Some(e);
return Event::Html(Owned(String::new()));
}
}
} else {
shortcode.append(&text);
return Event::Html(Owned(String::new()));
}
}
}
// Business as usual
Event::Text(text)
},
Event::Start(Tag::CodeBlock(ref info)) => {
in_code_block = true;
if !should_highlight {
return Event::Html(Owned("<pre><code>".to_owned()));
}
let theme = &THEME_SET.themes[&context.highlight_theme];
highlighter = SYNTAX_SET.with(|ss| {
let syntax = info
.split(' ')
.next()
.and_then(|lang| ss.find_syntax_by_token(lang))
.unwrap_or_else(|| ss.find_syntax_plain_text());
Some(HighlightLines::new(syntax, theme))
});
let snippet = start_coloured_html_snippet(theme);
Event::Html(Owned(snippet))
},
Event::End(Tag::CodeBlock(_)) => {
in_code_block = false;
if !should_highlight{
return Event::Html(Owned("</code></pre>\n".to_owned()))
}
// reset highlight and close the code block
highlighter = None;
Event::Html(Owned("</pre>".to_owned()))
},
// Need to handle relative links
Event::Start(Tag::Link(ref link, ref title)) => {
if in_header {
return Event::Html(Owned("".to_owned()));
}
if link.starts_with("./") {
match resolve_internal_link(link, context.permalinks) {
Ok(url) => {
return Event::Start(Tag::Link(Owned(url), title.clone()));
},
Err(_) => {
error = Some(format!("Relative link {} not found.", link).into());
return Event::Html(Owned("".to_string()));
}
};
}
Event::Start(Tag::Link(link.clone(), title.clone()))
},
Event::End(Tag::Link(_, _)) => {
if in_header {
return Event::Html(Owned("".to_owned()));
}
event
}
// need to know when we are in a code block to disable shortcodes in them
Event::Start(Tag::Code) => {
in_code_block = true;
if in_header {
temp_header.push("<code>");
return Event::Html(Owned(String::new()));
}
event
},
Event::End(Tag::Code) => {
in_code_block = false;
if in_header {
temp_header.push("</code>");
return Event::Html(Owned(String::new()));
}
event
},
Event::Start(Tag::Header(num)) => {
in_header = true;
temp_header = TempHeader::new(num);
Event::Html(Owned(String::new()))
},
Event::End(Tag::Header(_)) => {
// End of a header, reset all the things and return the stringified version of the header
in_header = false;
header_created = false;
let val = temp_header.to_string(context);
headers.push(temp_header.clone());
temp_header = TempHeader::default();
Event::Html(Owned(val))
},
// If we added shortcodes, don't close a paragraph since there's none
Event::End(Tag::Paragraph) => {
if added_shortcode {
added_shortcode = false;
return Event::Html(Owned("".to_owned()));
}
event
},
// Ignore softbreaks inside shortcodes
Event::SoftBreak => {
if shortcode_block.is_some() {
return Event::Html(Owned("".to_owned()));
}
event
},
_ => {
// println!("event = {:?}", event);
event
},
});
cmark::html::push_html(&mut html, parser);
}
if !current_shortcode.is_empty() {
return Err(format!("A shortcode was not closed properly:\n{:?}", current_shortcode).into());
}
match error {
Some(e) => Err(e),
None => Ok((html.replace("<p></p>", ""), make_table_of_contents(&headers))),
}
}