pub(crate) fn mask_code_block_triggers(source: &str) -> (String, Vec<char>)Expand description
Mask every Aozora trigger character that appears inside a fenced
code block. Returns the modified source and the ordered list of
original characters that were replaced (for use by unmask_html).
Returns (source.to_owned(), Vec::new()) and skips masking if the
source already contains MASK_CHAR — see the module docs for
the rationale.