Markdown: make links with spaces handling as per these standards

[artkpv]

Description

I find the way wiki.vim handles spaces in links confusing as it is clearly diverge from the standards: https://spec.commonmark.org/0.31.2/#links , https://github.github.com/gfm/#links, other. I mean that these are implemented by other apps:

• vim.markdown, https://github.com/preservim/vim-markdown/blob/master/doc/vim-markdown.txt#L236
• https://github.com/simov/markdown-viewer
• https://github.com/gsantner/markor
• others

Why not implement in wiki.vim?

Current behavior. A link [How to calculate contra amount](<How to calculate contra amount.md>) opens into <How to calculate contra amount.md>.md file.

Expected behavior. A link [How to calculate contra amount](<How to calculate contra amount.md>) opens into How to calculate contra amount.md.

Similarly for all other functionality: graph, tags, etc.

I guess, this should break current behavior that treats spaces inside link as a valid, i.e. [My link here](my page with spaces.md), but without < and > as an invalid link. I don't know exactly why those standards include this requirement.

Minimal working example

See above

[artkpv]

Refs #199

[lervag]

First, I'm very sorry for the late reply! It's been a very busy autumn and I've simply not been able to follow up as much as I want to.

Now, you are correct that I've not implemented the links perfectly according to specs. I've tried to make the example you submit slightly more clear by defining two files with links to each other:

!!! foo.md
# Foo title

[Link to bar](<bar.md>)
[Another link to bar][bar]


[bar]: <bar.md>

!!! bar.md
# Bar title

[Link to foo](foo.md)

I think one should expect all of these links to work in wiki.vim by default. Only one of them will work, though. So, I propose to update wiki.vim to handle the <...> syntax for the url part of Markdown links. I assume it is the same for reference style links, so I'll make sure that one works as well. Reference style links should already work as expected.

I would be happy if you could confirm my understanding of the issue. Let me know if I missed something or if you think my suggested solution is somehow wrong.

I guess, this should break current behavior that treats spaces inside link as a valid, i.e. [My link here](my page with spaces.md), but without < and > as an invalid link. I don't know exactly why those standards include this requirement.

I don't think we need to break this behaviour. I mean, I think a lot of tooling does support that style of links, and wiki.vim sure does.

[lervag]

I think a very simple solution that would "just work" is to strip the < and > from the URL when a link is first parsed, i.e. here:

wiki.vim/autoload/wiki/link/class.vim

Lines 11 to 16 in 969aecf

	" Parse link description and URL
	let l:link.text = ''
	let l:link.url = l:link.content
	call s:parse_from_content(l:link, a:link_definition, 'text')
	call s:parse_from_content(l:link, a:link_definition, 'url')
	let l:link.url_raw = l:link.url

I'm trying to think of why it might not be a good idea... I'll think about it for a day or two before committing to it.

[step-]

I can't think of too many reasons why stripping the angular brackets would be a bad idea but you are right to ponder.
Some things to keep in mind...

In CommonMark the <...> link syntax introduces an autolink, see the spec.
Autolinks require absolute URIs, otherwise they angular brackets are to be treated as regular text.
However, angular brackets in reference link definitions can be stripped. Here's an experiment, and its sanctioned CommomMark
outcome.

<http://example.com> # autolink

<this.md>  # regular text

<this file.md> # raw HTML tag

[this file.md]: <this file.md>

[this file.md] # reference link

[lervag]

Some things to keep in mind...

Thanks! But notice that the examples here are all a different type of link, and so not directly relevant to the question of <...>s in Markdown link urls.

For <...> style links, wiki.vim will understand it and handle it mostly correct. Although it will handle it wrong in cases where it should not be a link - i.e., wiki.vim is too acceptive. I think that's an OK choice. And I think it is OK also for markdown link urls.

[step-]

Sure, as for angular brackets in Markdown links, this is CommonMark's spec.

[lervag]

Ok; I've not thought of any reason this would be bad, so I've removed the angled brackets now. That should resolve this issue, I think.

[artkpv]

@lervag Thank you for your time and changes! I can't test this because other commit broke my setup. Pls see #383 (comment)

[lervag]

My pleasure! I think #395 (and thus #383) is resolved now, and if I'm right, then you should be able to test now. Sorry for the inconvenience!