…especially syntax highlighting.
This change brings in `morphdom` to allow us to be more efficient about how we apply the changes needed when the Markdown source re-renders. Instead of replacing all the content with every single change, we apply only the selective edits needed to adapt our existing markup to the target markup.
Once this process is done, we introduce one `TextEditor` instance for each `pre` tag in the markup, then persist those editor elements in the rendered output so that we don't have to spend so much time creating and destroying editors. This is a _huge_ performance win, especially in documents with lots of code blocks. The editor instances are cached using the `pre` elements as keys, which is now possible because the `pre` elements themselves are preserved across re-renders.
Editors are created when new `pre` elements appear, and are destroyed when they are no longer needed, change their contents whenever the contents of the `pre` changes, and change language modes whenever the code fence language identifier changes.
This approach is now used no matter which Markdown renderer is employed; we manage syntax highlighting ourselves in all cases rather than letting `atom.ui.markdown` do it.
…with one based on a better parser.
The `ikatyang` parser is great… until multi-byte input comes into play, or some other construct it doesn't understand. It doesn't have any way to recover when it hits those cases; it just throws exceptions, and WASM can't catch them.
The `MDeiml` parser for Markdown had one deal-breaking issue (https://github.com/tree-sitter-grammars/tree-sitter-markdown/issues/92), and once that got solved, it emerged as the clear victor.
Several people have been using this grammar as `language-markdown-alpha` on the repository, and none of them have encountered any problems of the sort they did with the `ikatyang` parser.
If it throws the Exception, other valid uris such as atom://teletype/...
will not be evaluated in the else branch
The old fs-plus did not throw.
Newer versions of fs.lstatSync allow for option parameter to control if it throws.
* When set to `true`, `hideDuplicateTextMateGrammars` will hide all grammars except whichever one the user has indicated a preference for — via `useTreeSitterParsers` and `useLegacyTreeSitter` settings, whether global or scope-specific.
* When set to `false`, `hideDuplicateTextMateGrammars` will show all grammars, even Legacy Tree-sitter.
