Add configuration option to disable the default hidelines feature for rust

Author: zgtm

crates/mdbook-core/src/config.rs

@@ -560,14 +560,25 @@ impl Default for Playground {
 }
 
 /// Configuration for tweaking how the HTML renderer handles code blocks.
-#[derive(Debug, Default, Clone, PartialEq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case", deny_unknown_fields)]
 #[non_exhaustive]
 pub struct Code {
+    /// Enable or disable the default line hiding with '#' for rust. Default: `true`.
+    pub default_hidelines: bool,
     /// A prefix string to hide lines per language (one or more chars).
     pub hidelines: HashMap<String, String>,
 }
 
+impl Default for Code {
+    fn default() -> Code {
+        Code {
+            default_hidelines: true,
+            hidelines: HashMap::<String, String>::default(),
+        }
+    }
+}
+
 /// Configuration of the search functionality of the HTML renderer.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case", deny_unknown_fields)]

crates/mdbook-html/src/html_handlebars/hbs_renderer.rs

@@ -901,7 +901,7 @@ fn hide_lines(html: &str, code_config: &Code) -> String {
             let classes = &caps[2];
             let code = &caps[3];
 
-            if classes.contains("language-rust") {
+            if classes.contains("language-rust") && code_config.default_hidelines {
                 format!(
                     "<code class=\"{}\">{}</code>",
                     classes,
@@ -1311,6 +1311,38 @@ mod tests {
         }
     }
 
+    #[test]
+    fn no_default_hide_lines() {
+        let inputs = [
+            (
+                "<pre class=\"playground\"><code class=\"language-rust\">\n# #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>",
+                "<pre class=\"playground\"><code class=\"language-rust\">\n# #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>",
+            ),
+            (
+                "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",
+                "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",
+            ),
+            (
+                "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>",
+                "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>",
+            ),
+            (
+                "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>",
+                "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>",
+            ),
+            (
+                "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
+                "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
+            ),
+        ];
+        let mut code = Code::default();
+        code.default_hidelines = false;
+        for (src, should_be) in &inputs {
+            let got = hide_lines(src, &code);
+            assert_eq!(&*got, *should_be);
+        }
+    }
+
     #[test]
     fn test_json_direction() {
         assert_eq!(json!(TextDirection::RightToLeft), json!("rtl"));