fix(#73) do not disturb code block detection when preventing escape

src/source_range.rs

@@ -39,21 +39,27 @@ where
     for (event, range) in event_and_ranges {
         let update_event_end_index = !matches!(*event.borrow(), Event::Start(_));
         let prevent_escape_leading_special_characters = match (&range, event.borrow()) {
+            // IMPORTANT: Any changes that allow anything other than `Text`
+            // breaks the assumption below.
             (Some(range), Event::Text(_)) => {
                 range.start <= state.last_event_end_index ||
                 // Some source characters are not captured,
                 // so check the previous character.
                 source.as_bytes().get(range.start.saturating_sub(1)) != Some(&b'\\')
             }
             _ => false,
-        };
-        let was_in_code_block = state.is_in_code_block;
+        } && !state.is_in_code_block;
         if prevent_escape_leading_special_characters {
             // Hack to not escape leading special characters.
             state.is_in_code_block = true;
         }
         cmark_resume_one_event(event, &mut formatter, &mut state, &options)?;
-        state.is_in_code_block = was_in_code_block;
+        if prevent_escape_leading_special_characters {
+            // Assumption: this case only happens when `event` is `Text`,
+            // so `state.is_in_code_block` should not be changed to `true`.
+            // Also, `state.is_in_code_block` was `false`.
+            state.is_in_code_block = false;
+        }
 
         if let (true, Some(range)) = (update_event_end_index, range) {
             state.last_event_end_index = range.end

tests/fmt.rs

@@ -423,6 +423,34 @@ mod inline_elements {
         )
     }
 
+    #[test]
+    fn no_escaping_special_character_in_code() {
+        // https://github.com/Byron/pulldown-cmark-to-cmark/issues/73
+        let input = r#"
+```rust
+# fn main() {
+println!("Hello, world!");
+# }
+```
+"#;
+        let iter = pulldown_cmark::Parser::new(input);
+        let mut actual = String::new();
+        pulldown_cmark_to_cmark::cmark_with_source_range_and_options(
+            iter.map(|e| (e, None)),
+            input,
+            &mut actual,
+            Default::default(),
+        )
+        .unwrap();
+        let expected = r#"
+````rust
+# fn main() {
+println!("Hello, world!");
+# }
+````"#;
+        assert_eq!(actual, expected);
+    }
+
     #[test]
     fn rustdoc_link() {
         // Brackets are not escaped if not escaped in the source.