Introduce an enum for a separate highlighted src block type.

src/intermediate/src_block.rs

@@ -1,3 +1,4 @@
+use std::borrow::Borrow;
 use std::borrow::Cow;
 
 use super::macros::intermediate;
@@ -9,7 +10,20 @@ use tree_sitter_highlight::HighlightEvent;
 use tree_sitter_highlight::Highlighter;
 
 #[derive(Debug, Clone)]
-pub(crate) struct ISrcBlock {
+pub(crate) enum ISrcBlock {
+    Plain(PlainSrcBlock),
+    Highlighted(HighlightedSrcBlock),
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct PlainSrcBlock {
+    pub(crate) lines: Vec<String>,
+    pub(crate) language: Option<String>,
+    pub(crate) post_blank: organic::types::PostBlank,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct HighlightedSrcBlock {
     pub(crate) lines: Vec<String>,
     pub(crate) language: Option<String>,
     pub(crate) post_blank: organic::types::PostBlank,
@@ -66,18 +80,20 @@ intermediate!(
             .collect();
         let language = original.language.map(str::to_owned);
 
-        let lines = match language.as_ref().map(String::as_str) {
+        match language.as_ref().map(String::as_str) {
             Some("nix") => {
-                // foo
-                highlight_nix(lines)?
+                let highlighted = highlight_nix(&lines);
+                if let Ok(highlighted) = highlighted {
+                    // return the other type
+                }
             }
-            _ => lines,
+            _ => {}
         };
-        Ok(ISrcBlock {
+        Ok(ISrcBlock::Plain(PlainSrcBlock {
             lines,
             language,
             post_blank: original.get_post_blank(),
-        })
+        }))
     }
 );
 
@@ -91,7 +107,10 @@ fn ascii_whitespace_value(c: char) -> usize {
     }
 }
 
-fn highlight_nix(lines: Vec<String>) -> Result<Vec<String>, CustomError> {
+fn highlight_nix<L>(lines: &[L]) -> Result<Vec<String>, CustomError>
+where
+    L: Borrow<str>,
+{
     let highlight_names = ["comment", "keyword"];
     // Need 1 highlighter per thread
     let mut highlighter = Highlighter::new();