JakeQZ

Sounds like a good idea. Like Psalm (until a week ago), something I know absolutely nothing about :)

Makes sense - as they can share the same `DOMDocument`, and there's no reason (I can think of) why `HtmlPruner` can't be instantiated first, then `CssInliner` with `::fromDomDocument`, and the...

It might be an idea to initially mark the method as deprecated for 4.0, and change the current implementation to create a temporary `HtmlPruner` to invoke the functionality (though a...

> As for the refactoring by using `HtmlPruner` internally, I'd like to avoid this as this code will be removed anyway. That was partly based on a presumption that there'd...

> The emogrifer landing page has a list of sites that we're aware of: https://www.myintervals.com/emogrifier.php I can't see a list there. Any website using a somewhat recent (< 3 years?)...

I forgot to add the RFC822 `.eml` attachment, so here it is (you'll have to rename the file because GitHub only supports attachments with certain file extensions): [boolean-attribute-test.eml](https://github.com/MyIntervals/emogrifier/files/4659399/boolean-attribute-test.eml.txt) I've now...

See https://github.com/MyIntervals/emogrifier/pull/831#discussion_r429501323 Really, an option to short-circuit the namespace tests and simply return `true` for anything in that list in [OutputRules::nonBooleanAttributes](https://github.com/Masterminds/html5-php/blob/2.7.0/src/HTML5/Serializer/OutputRules.php#L70). However, I think that list is back to front....

First question: is this something that would be considered 'core' functionality, or something that should go into a HtmlProcessor class (presumably `HtmlMinifier`) as outlined in #479? Data for CSS shorthand...

Ok. I think some common functionality would need to be shared between `Emogrifier` and `CssMinifier`, notably `parseCssDeclarationsBlock`, `attributeValueIsImportant` and `generateStyleStringFromSingleDeclarationsArray`. Whilst these are fairly stand-alone, they do use two caches...

Presumably then `AbstractHtmlProcessor` would have a private no-argument constructor and private methods `initializeFromHtml` and `initializeFromDomDocument` which would be called by the public `fromHtml` and `fromDomDocument`. In terms of retro-fitting the...