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Add basic syntax highlighting support with syntect. Closes #5.

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This commit is contained in:
Quin 2025-07-05 22:28:16 -06:00
parent 3897b8dd30
commit cd5c12ff21
3 changed files with 89 additions and 6 deletions
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89
htmlua-parser/src/render.rs
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@ -4,6 +4,13 @@ use anyhow::{Result, anyhow};
use kuchikiki::{NodeRef, traits::TendrilSink};
use mlua::{Lua, Table};
use pulldown_cmark::{Options, Parser, html};
use syntect::{
easy::HighlightLines,
highlighting::{Style, ThemeSet},
html::{IncludeBackground, styled_line_to_highlighted_html},
parsing::SyntaxSet,
util::LinesWithEndings,
};
fn create_htmlua_stdlib(l: &Lua, stdout: &Rc<RefCell<String>>) -> mlua::Result<Table> {
let t = l.create_table()?;
@ -119,7 +126,9 @@ pub fn expand_template(document: NodeRef, component_path: &PathBuf, include_from
item_path.push(include_path);
let component_text = read_to_string(item_path)?;
let new_doc = kuchikiki::parse_html().one(component_text);
let new_node = new_doc.select_first("body").map_err(|()| anyhow!("Failed to get body"))?;
let new_node = new_doc
.select_first("body")
.map_err(|()| anyhow!("Failed to get body"))?;
let replaced_node = expand_template(new_node.as_node().clone(), component_path, Some(i.as_node()))?;
i.as_node().insert_before(replaced_node);
i.as_node().detach();
@ -128,6 +137,49 @@ pub fn expand_template(document: NodeRef, component_path: &PathBuf, include_from
Ok(document)
}
pub fn process_syntax_highlighting(document: NodeRef) -> Result<NodeRef> {
let ps = SyntaxSet::load_defaults_newlines();
let ts = ThemeSet::load_defaults();
let syntax_elements: Vec<_> = match document.select("syntaxhighlight") {
Ok(e) => e.collect(),
Err(()) => return Err(anyhow!("Unable to find syntaxhighlight elements")),
};
for node in syntax_elements {
let attrs = match node.as_node().as_element() {
Some(e) => e.attributes.borrow(),
None => continue,
};
let language = attrs.get("lang").unwrap_or("text");
let theme_name = attrs.get("theme").unwrap_or("base16-ocean.dark");
if let Some(text_node) = node.as_node().first_child() {
if let Some(code_text) = text_node.as_text() {
let syntax = ps
.find_syntax_by_extension(language)
.or_else(|| ps.find_syntax_by_name(language))
.unwrap_or_else(|| ps.find_syntax_plain_text());
let theme = &ts.themes[theme_name];
let mut h = HighlightLines::new(syntax, theme);
let mut html_output = String::new();
write!(html_output, r#"<pre class="syntax-highlight" data-lang="{language}">"#)?;
html_output.push_str("<code>");
for line in LinesWithEndings::from(&code_text.borrow()) {
let ranges: Vec<(Style, &str)> = h.highlight_line(line, &ps).unwrap();
let escaped = styled_line_to_highlighted_html(&ranges[..], IncludeBackground::No).unwrap();
html_output.push_str(&escaped);
}
html_output.push_str("</code></pre>");
let html_fragment = kuchikiki::parse_html().one(html_output);
for child in html_fragment.children() {
node.as_node().insert_before(child);
}
// Remove the original syntaxhighlight node.
node.as_node().detach();
}
}
}
Ok(document)
}
#[cfg(test)]
mod tests {
use super::*;
@ -237,7 +289,6 @@ mod tests {
let text = d.select_first("#inc1").unwrap().as_node().text_contents();
assert_eq!(text, "included1");
assert!(d.select_first("include").is_err());
}
#[test]
@ -292,7 +343,7 @@ mod tests {
#[test]
fn basic_markdown() {
let page = r#"
let page = r"
<!DOCTYPE html>
<html>
<head>
@ -311,11 +362,41 @@ This is a paragraph with **bold text** and *italic text*.
</markdown>
</div>
</body>
</html>"#;
</html>";
let document = kuchikiki::parse_html().one(page);
let d = process_markdown(document).unwrap();
assert!(d.select_first("markdown").is_err());
assert!(d.select_first("p").is_ok());
assert!(d.select_first("ul").is_ok());
}
#[test]
fn basic_syntax_highlighting() {
let page = r#"
<!DOCTYPE html>
<html>
<head>
<title>Syntax Highlighting Test</title>
</head>
<body>
<h1>Code Example</h1>
<syntaxhighlight lang="rust">
fn main() {
println!("Hello, world!");
let x = 42;
let y = "test";
}
</syntaxhighlight>
</body>
</html>"#;
let document = kuchikiki::parse_html().one(page);
let d = process_syntax_highlighting(document).unwrap();
assert!(d.select_first("syntaxhighlight").is_err());
assert!(d.select_first("pre").is_ok());
assert!(d.select_first("code").is_ok());
let pre = d.select_first("pre").unwrap();
let attrs = pre.attributes.borrow();
assert_eq!(attrs.get("data-lang"), Some("rust"));
assert!(attrs.get("class").unwrap().contains("syntax-highlight"));
}
}