Combination of italic with custom markdown element not working

[S2V]

Reproducible for the case when text has mixed text-decoration style with custom markdown element. In my case. I have the custom element that not supports by markdown be default - underline(++). I implement the custom markdown element for parsing (like MarkdownStrikethrough).

class MarkdownUnderline: MarkdownCommonElement {
	
	var font: MarkdownFont?
	var color: MarkdownColor?
	
	private static let regex = "(.?|^)(\\+\\+)(?=\\S)(.+?)(?<=\\S)(\\2)"

	var regex: String {
		return MarkdownUnderline.regex
	}
	
	public init(font: MarkdownFont?, color: MarkdownColor? = nil) {
		self.font = font
		self.color = color
	}
	
	public func match(_ match: NSTextCheckingResult, attributedString: NSMutableAttributedString) {
		attributedString.deleteCharacters(in: match.range(at: 4))

		var attributes = attributedString.attributes(
			at: match.range(at: 3).location,
			longestEffectiveRange: nil,
			in: match.range(at: 3)
		)

		attributes[.underlineStyle] = NSNumber.init(value: NSUnderlineStyle.single.rawValue)

		attributedString.addAttributes(attributes, range: match.range(at: 3))

		attributedString.deleteCharacters(in: match.range(at: 2))
	}
}

But parsing result is not correct, for example for text **_++Lorem ipsum++_** will be produced the attributed text:

_++Lorem ipsum++_

If I change the regex to (.?|^)(\\*|_)(?=\\S)(.+?)(?<=\\S)(\\2) ,that was implemented for fix, the parsing result is correct.

[gaebel]

I tried parsing with your custom element and it works fine. The last merged PRs haven't been published yet, though. Do you possibly use the latest version (1.7.1)? If yes, could you check if switching to the master branch fixes your issue?

[S2V]

@gaebel Yep, you are right. I provided a not correct example, sorry - that is my bad. If be more correct - parsing result for **_++ Lorem ipsum++_** is correct, but if you change the order of applying the styles to ++_**Lorem ipsum**_++ - result will be not correct.
Test text:

let test = """
 ++_**Mixed U/I/B Cras non erat dolor. In euismod laoreet iaculis. Aliquam viverra rutrum dui, at volutpat orci tempus et.**_++

 **_++Mixed B/I/U Cras non erat dolor. In euismod laoreet iaculis. Aliquam viverra rutrum dui, at volutpat orci tempus et.++_**
"""

Result 1.7.1:

Result master: 072e192:

Result master: 072e192 + modified regex for italic element to(.?|^)(\\*|_)(?=\\S)(.+?)(?<=\\S)(\\2):

Looks like order makes sense.

[gaebel]

I've made some changes to the regex, and the attribute inheritance. This should be fixed now.

[Mr-Sergey-K]

@gaebel Release this fix please