Smart padding

[hzhongmj]

A detailed description of the feature you would like to see added.

When table has a whitespace as border, it can look quite cramped, especially when the cells have text with whitespaces. For example, below is a sample output of a certain table:

     Line  User  Idle     Location
-- ------- ----- -------- --------------------------------------
   1 con 0 root  07:29:04 -
   2 vty 3 root  09:12:23 10.243.214.227
   3 vty 5 root  07:09:36 10.243.214.212
*  4 vty 7 admin 00:00:00 fdfd:5c41:712d:d08e:2ce2:7eff:fea5:ae5

As you can see most of the columns (especially the second and third) are separated by just a single whitespace which makes it rather hard to read.

The idea of smart padding is to detect that two adjacent cells are only separated by one whitespace, in which case we add one more whitespace between the two columns. With smart padding the above table would look like:

     Line   User   Idle      Location
-- -------- ------ --------- --------------------------------------
   1 con 0  root   07:29:04  -
   2 vty 3  root   09:12:23  10.243.214.227
   3 vty 5  root   07:09:36  10.243.214.212
*  4 vty 7  admin  00:00:00  fdfd:5c41:712d:d08e:2ce2:7eff:fea5:ae5

Smart padding does not take effect if one of the condition is true:
1. There is no extra space left
2. The left column is right aligned and the right column is left aligned

I have an implementation below:
hzhongmj@0517929

Please let me know what you think.

Explain your usecase of the requested feature

The smart padding tries to make the padding a bit smarter and only adds extra whitespace when it's necessary (affecting readability). Without this feature we'd have to add the padding unconditionally for all columns which could be wasteful and undesirable.

Alternatives

Manually manage each column to decide whether to add extra padding, but it can only be done statically instead of adjusting to dynamic content.

Additional context

No response

[Nukesor]

Hey :)

Generally, this sounds like a reasonable addition.

I'm currently a bit preoccupied with other things, but I'll properly review your changes as soon as a I'm back from holiday and finding some spare time (which will be earliest in 2~3 weeks) :)

A bit of early feedback:

1. I'm not a big fan of the "only do this if there's one whitespace" rule. That condition is too specific.
   If we include this feature, it should cover more use-cases. What comes to mind is that users can specify a "target" padding that should be reached if there's available space. For example, it would be nice to have a padding of (2,2), but if there's no space, the padding will default to (0,0). IMO, it should also be possible to apply this to all ContentArrangement modes (Dynamic, DynamicFull, and Disabled mode). For the Disabled and Dynamic mode this is relatively straight-forward. For the DynamicFull mode however, the logic needs to happen before the rest of the space is distributed to all columns, so that could be a bit more tricky^^.
2. This doesn't need to be hidden behind a feature flag. As long as this whole functionality is disabled by default and can be toggled via a config function, it can easily be included into the default set of features :). We only use feature flags for things that: a) always negatively impact performance b) require dependencies that aren't available in all environments (e.g. non-tty).
3. Your code looks unformatted. This'll be caught by the CI anyway, but take a look at the just format command.

[hzhongmj]

Thanks for the feedback! I'll incorporate it into my next round of changes.

[hzhongmj]

I just sent a PR. I addressed your comments 2&3. For 1, I made it smart_padding_width:u16 instead of a boolean.

It now works for both Disabled and Dynamic, but for DynamicFullWidth I don't think it's very useful (since we'll utilize more space anyway), so I have not spent the time to investigate.