Support parsing metadata

Main purpose of adding multiline comments to vimwiki was so we could properly find and parse metadata that wouldn't be included in the HTML output (and can also be concealed, etc).

What format should the metadata take? We will be using the multiline comment syntax to start of %%+ and +%%.

Proposal 1: Emacs Org Mode Drawer Mode + Clocking

Drawer Mode Reference: Link Clocking Reference: Link Example Video of Clocking: Link Org-Pomodoro Plugin: Link

Pros

Established, mature pattern following org mode

Cons

Overly verbose, multi-line which is a bit ugly to me
Could be difficult to parse

Examples

** This is a headline
     Still outside the drawer
     :CLOCKING:
     CLOCK: [2020-08-01 18:32]
     :END:
     After the drawer.

- [ ] Some task
   %%+ :CLOCKING: 
   CLOCK: [2020-08-01 18:32]
   :END: +%%

with extra properties if we make stuff up

- [ ] Some task
   %%+ :CLOCKING: 
   CLOCK: [2020-08-01 18:32]
   POMODORO: 3
   :END: +%%

Proposal 2: Embed JSON

Still need a way to determine if metadata, so would need some indication when beginning multiline comment.

Could do %%++ or some variant like that. Or could have a special keyword like %%+:meta:.

Pros

Can fit in a single line
Easily parseable using json_decode from vim

Cons

Still not human readable
Still a bit more verbose, involving quoting keys and string values

Examples

- [ ] Some task %%++ {"clock": "2020-08-01 18:32"} +%%

with extra properties if we make stuff up

- [ ] Some task %%++ {"clock": "2020-08-01 18:32","pomodoro": 3} +%%

Proposal 3: Custom Human Readable

Pros

Can possibly make more compact and keep readable than other options

Cons

Not a defined standard
Could be difficult to parse

Examples

- [ ] Some task %%+:clock=2020-08-01 18:32:+%%

with extra properties if we make stuff up

- [ ] Some task %%+:clock=2020-08-01 18:32:pomodoro=3:+%%

chipsenkbeil / vimwiki.nvim