A realm filter should match only after the start of a line, whitespace
or opening delimiters. But markdown was not configured to respect those
rules which was causing some weird rendering behavior. This commit fixes
the regex used for matching realm filters. On the backend we are using
regex with negative lookbehind to perform matches but since javascript
regex don't support lookbehind we are using a workaround on the frontend
using `contains_backend_only_syntax()` function which detects if a realm
filter can be rendered correctly by backend only and if so it stops the
message from getting echoed locally.
Fixes: #5154.
While we do have some known cases where syntax diverges intentionally,
this change should make it a lot easier to maintain
markdown.contains_backend_only_syntax over time.
This commit removes all code related to headers because
(1) we don't need the code and (2) it splits #**stream**
as a paragraph, which we don't want. This commit also
fixes the inconsistency when #**stream** is on a new line.
Fixes#4678.
The user mention regex was checking for multiple lines,
so it broke when the user mention was on a new line.
This changes the regex AND adds a couple tests to
test inline markdown regexes.
Unicode emojis when rendered should display canonical short name.
Similarly, the alt text should be of the format `:<short_name>:`.
For both of these we currently display the actual unicode symbol.
As some systems don't have the fonts necessary for displaying them
properly, they are rendered as empty square blocks. This commit also
ensures that the markup generated for emoji generated by canonical
name and by an unicode emoji is same.
Fixes: #5555.
Harshit Bansal
Tim Abbott
Joshua Pan
digi0ps
Cory Lynch
Yago González
Steve Howell