Export subheadings and content before subheading in context of the whole file

[renatgalimov]

Fixes #24

Previous version of this code was exporting content subheadings and content before subheading aside of their context, which caused broken links for attachments (see #24).

After this PR we export subheadings and content before subheadings as a region and org-export remains aware of all available properties.

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Besides that, I added unit tests to ensure that I didn't break anything.

[renatgalimov]

I will return to this PR next week.

[renatgalimov]

I got something useful here. Now I can export notes with attachments. @orgtre, any ideas about this PR?

[renatgalimov]

This diff breaks anki-editor--map-fields, but I will deal with it later.

[renatgalimov]

The whole idea worked pretty well.

But sometimes my code doesn't work properly in a big chunk of code called in anki-editor--map-fields[1]. It's a bit scary to try to fix it because the code is really big and complicated. Maybe it would be better to make it simpler first so it's easier to understand and find what's causing the problem.

[1] https://github.com/orgtre/anki-editor/blob/ab7b33b48c78cb909391622eeffb893829b382d7/anki-editor.el#L891-L958

[shunlog]

But sometimes my code doesn't work properly in a big chunk of code called in anki-editor--map-fields

What exactly doesn't work?

[renatgalimov]

@shunlog - I fixed the anki-editor--map-fields.

Now, the note is exported not from a string but from a region, and the export is now aware about the org export context.

Also, I added a few unit tests to check how the export works.

But I don't want to make more progress before @orgtre sees the diff.

Currently, I use thia branch version of anki-editor.

[slotThe]

@renatgalimov is there anything you'd still like to do here? The code looks fine to me and the added tests are great!

[slotThe]

N.b.: as someone who regularly pushes large subtrees of notes over to anki, I did notice a slowdown of at least one order of magnitude with this PR. I haven't profiled this yet, and I suspect it's fixable, but just something to keep in mind.

Since it fixes a bunch of outstanding issues (e.g., #38 and #39) the PR still seems worth merging, although one should definitely study the performance regression further

[slotThe]

It seems like the reliance on org-export-as makes thing far from performant—plus, we spend over half of the time garbage collecting! Perhaps there was a reason the old code was manually assembling the strings for the fields.

@renatgalimov is it perhaps possible to keep anki-editor--map-fields as unchanged as possible, only fixing the problem in #24?

[renatgalimov]

@slotThe, I can try to refactor it.

@renatgalimov is there anything you'd still like to do here? The code looks fine to me and the added tests are great!

Thanks! I want to refactor the tests, as I don't like having a Python program to serve them.

It seems like the reliance on org-export-as makes thing far from performant—plus, we spend over half of the time garbage collecting! Perhaps there was a reason the old code was manually assembling the strings for the fields.

I can make it configurable, maintain old behavior by default, and enable the new one with a flag or setting.

@renatgalimov is it perhaps possible to keep anki-editor--map-fields as unchanged as possible

I will check it.