Initial highlighting code.

The dust auto-escaping is causing this naive approach to fail so I will have to create a distinction between highlighted code and not-highlighted code.

src/intermediate/src_block.rs

@@ -1,6 +1,12 @@
+use std::borrow::Cow;
+
 use super::macros::intermediate;
 use crate::error::CustomError;
 use organic::types::StandardProperties;
+use tree_sitter_highlight::Highlight;
+use tree_sitter_highlight::HighlightConfiguration;
+use tree_sitter_highlight::HighlightEvent;
+use tree_sitter_highlight::Highlighter;
 
 #[derive(Debug, Clone)]
 pub(crate) struct ISrcBlock {
@@ -59,6 +65,14 @@ intermediate!(
             })
             .collect();
         let language = original.language.map(str::to_owned);
+
+        let lines = match language.as_ref().map(String::as_str) {
+            Some("nix") => {
+                // foo
+                highlight_nix(lines)?
+            }
+            _ => lines,
+        };
         Ok(ISrcBlock {
             lines,
             language,
@@ -76,3 +90,57 @@ fn ascii_whitespace_value(c: char) -> usize {
         _ => unreachable!("Only ascii whitespace can reach this code."),
     }
 }
+
+fn highlight_nix(lines: Vec<String>) -> Result<Vec<String>, CustomError> {
+    let highlight_names = ["comment", "keyword"];
+    // Need 1 highlighter per thread
+    let mut highlighter = Highlighter::new();
+    let language = tree_sitter_nix::LANGUAGE.into();
+    let mut config =
+        HighlightConfiguration::new(language, "nix", tree_sitter_nix::HIGHLIGHTS_QUERY, "", "")
+            .unwrap();
+    config.configure(&highlight_names);
+
+    let combined_text = lines.join("");
+
+    let highlights = highlighter
+        .highlight(&config, combined_text.as_bytes(), None, |_| None)
+        .unwrap();
+
+    let mut highlighted_text = Vec::new();
+    for event in highlights {
+        match event.unwrap() {
+            HighlightEvent::Source { start, end } => {
+                highlighted_text.push(Cow::Borrowed(&combined_text[start..end]));
+            }
+            HighlightEvent::HighlightStart(s) => {
+                let class_name = format!("srchl_{}", highlight_names[s.0]);
+                highlighted_text.push(Cow::Owned(format!(r#"<span class="{}">"#, class_name)));
+            }
+            HighlightEvent::HighlightEnd => {
+                highlighted_text.push(Cow::Borrowed(r#"</span>"#));
+            }
+        }
+    }
+
+    let highlighted_text = highlighted_text.join("");
+    let lines = highlighted_text
+        .split_inclusive('\n')
+        .map(str::to_owned)
+        .collect();
+    Ok(lines)
+}
+
+// use tree_sitter::Parser;
+// fn dump_nix<B>(body: B) -> Result<(), CustomError>
+// where
+//     B: AsRef<str>,
+// {
+//     let mut parser = Parser::new();
+//     parser
+//         .set_language(&tree_sitter_nix::LANGUAGE.into())
+//         .expect("Error loading Nix grammar");
+//     let mut tree = parser.parse(body.as_ref(), None).unwrap();
+//     println!("{}", tree.root_node());
+//     Ok(())
+// }