TLDR; this commit vastly improves how whitespaces are handled when converting from HTML to Markdown.
It also adds support for converting HTML <tables> to markdown tables.
The previous 'remove_whitespaces!' method was traversing the whole HTML tree and used a heuristic to remove
leading and trailing whitespaces whenever it was appropriate (ie. mostly before and after HTML block elements)
It was a good idea, but it was very limited and leaded to bad conversion when the html had leading whitespaces on several lines for example.
One such example can be found [here](https://meta.discourse.org/t/86782).
For various reasons, most of the whitespaces in a HTML file is ignored when the page is being displayed in a browser.
The rules that the browsers follow are the [CSS' White Space Processing Rules](https://www.w3.org/TR/css-text-3/#white-space-rules).
They can be quite complicated when you take into account RTL languages and other various tidbits but they boils down to the following:
- Collapse whitespaces down to one space (0x20) inside an inline context (ie. nodes/tags that are being displaying on the same line)
- Remove any leading/trailing whitespaces inside an inline context
One quick & dirty way of getting this 90% solved would be to do 'HTML.gsub!(/[[:space:]]+/, " ")'.
We would also need to hoist <pre> elements in order to not mess with their whitespaces.
Unfortunately, this solution let some whitespaces creep around HTML tags which leads to more '.strip!' calls than I can bear.
I decided to "emulate" the browser's handling of whitespaces and came up with a solution in 4 parts
1. remove_not_allowed!
The HtmlToMarkdown library is recursively "visiting" all the nodes in the HTML in order to convert them to Markdown.
All the nodes that aren't handled by the library (eg. <script>, <style> or any non-textual HTML tags) are "swallowed".
In order to reduce the number of nodes visited, the method 'remove_not_allowed!' will automatically delete all the nodes
that have no "visitor" (eg. a 'visit_<tag>' method) defined.
2. remove_hidden!
Similar purpose as the previous method (eg. reducing number of nodes visited), there's no point trying to convert something that is hidden.
The 'remove_hidden!' method removes any nodes that was hidden using the "hidden" HTML attribute, some CSS or with a width or height equal to 0.
3. hoist_line_breaks!
The 'hoist_line_breaks!' method is there to handle <br> tags. I know those tiny <br> don't do much but they can be quite annoying.
The <br> tags are inline elements but they visually work like a block element (ie. they create a new line).
If you have the following HTML "<i>Foo<br>Bar</i>", it ends up visually similar to "<i>Foo</i><br><i>Bar</i>".
The latter being much more easy to process than the former, so that's what this method is doing.
The "hoist_line_breaks" will hoist <br> tags out of inline tags until their parent is a block element.
4. remove_whitespaces!
The "remove_whitespaces!" is where all the whitespace removal is happening. It's broken down into 4 methods as well
- remove_whitespaces!
- is_inline?
- collapse_spaces!
- remove_trailing_space!
The 'remove_whitespace!' method is recursively walking the HTML tree (skipping <pre> tags).
If a node has any children, they will be chunked into groups of inline elements vs block elements.
For each chunks of inline elements, it will call the "collapse_space!" and "remove_trailing_space!" methods.
For each chunks of block elements, it will call "remote_whitespace!" to keep walking the HTML tree recursively.
The "is_inline?" method determines whether a node is part of a inline context.
A node is inline iif it's a text node or it's an inline tag, but not <br>, and all its children are also inline.
The "collapse_spaces!" method will collapse any kind of (white) space into a single space (" ") character, even accros tags.
For example, if we have " Foo \n<i> Bar </i>\t42", it will return "Foo <i>Bar </i>42".
Finally, the "remove_trailing_space!" method is there to remove any trailing space that might creep in at the end of the inline chunk.
This solution is not 100% bullet-proof.
It does not support RTL languages at all and has some caveats that I felt were not worth the work to get properly fixed.
FIX: better detection of hidden elements when converting HTML to Markdown
FIX: take into account the 'allowed_href_schemes' site setting when converting HTML <a> to Markdown
FIX: added support for 'mailto:' scheme when converting <a> from HTML to Markdown
FIX: added support for <img> dimensions when converting from HTML to Markdown
FIX: added support for <dl>, <dd> and <dt> when converting from HTML to Markdown
FIX: added support for multilines emphases, strongs and strikes when converting from HTML to Markdown
FIX: added support for <acronym> when converting from HTML to Markdown
DEV: remove unused 'sanitize' gem
Wow, did you just read all that?! Congratz, here's a cookie: 🍪.
pry-nav is not yet supported on latest pry, this holds off on
upgrading pry, which in turn holds off on upgrading deps
Stripping pry-nav for now till it works with latest pry
Latest version of Rails contains compatibility fixes for Ruby 2.7 and some
minor security fixes we would like to have
It also broke some of the multisite tests.
Rails tries to use the same connection for reading from a replica as writing
to the leader during tests, because, with everything happening in a
transaction, changes to the DB wouldn't otherwise be reflected in the
replica connection.
The difference now is that Rails tries to do this for connections opened
after the test has started which affected rails multisite connections.
The upshot of this is that, as things stand, you are likely to
experience problems if you try to connect to a different multisite DB in
a test when the `current_db` is not 'default'.
This adds rubocop-rspec, and enables some cops that were either already passing or are passing now, after fixing them in this commit.
Some new cops are disabled for now, with annotation: "TODO" or "To be decided". Those either need to be discussed first, or require manual changes, or the number of found and fixed offenses is too large to bundle them up in a single PR.
Includes:
* DEV: Update rubocop's `TargetRubyVersion` to 2.6
* DEV: Enable RSpec/VoidExpect
* DEV: Enable RSpec/SharedContext
* DEV: Enable RSpec/EmptyExampleGroup (Removed an obsolete empty spec file)
* DEV: Enable RSpec/ItBehavesLike
* DEV: Remove RSpec/ScatteredLet (It's too strict, as it doesn't recognize fab! as a let-like)
* DEV: Remove RSpec/MultipleExpectations
Previously we would consider a user "present" and "last seen" if the
browser window was visible.
This has many edge cases, you could be considered present and around for
days just by having a window open and no screensaver on.
Instead we now also check that you either clicked, transitioned around app
or scrolled the page in the last minute in combination with window
visibility
This will lead to more reliable notifications via email and reduce load of
message bus for cases where a user walks away from the terminal
This is a minor update to unicorn, in this update unicorn handles
chunked encoding a bit more correctly according to RFC
Should have no impact, but message bus will be validated in production
to confirm chunked encoding still works as expected
json is shipped out of sync with Ruby. Even though we use OJ for many things
we still use the json gem sometimes, this ensures we use the latest
b8b29e79ad/config/initializers/100-oj.rb (L9-L9)
dependabot-preview[bot]
Régis Hanol
Sam Saffron
Robin Ward
David Taylor
Blake Erickson
Guo Xiang Tan
Jarek Radosz
Daniel Waterworth