feat: allow users to supply custom distance functions #66

[johnlevidy]

I explored different options, but ultimately it seems sorting the distance is the only way to get consistent read-wise ordering. The custom function doesn't take xbias, since users can supply that themselves, and win_bias is borrowed from elsewhere, since window params are not ( yet? ) provided to the custom function.

Tested with this config:

local hop = require('hop')

local readwise_distance = function(a, b)
        return (100 * math.abs(b.row - a.row)) + (b.col - a.col);
end

hop.setup{keys = 'asdfjklqweruiopzxmtgbyhn', x_bias = 10,
          custom_distance_fn = readwise_distance }

local directions = require('hop.hint').HintDirection
vim.keymap.set({'o', 'n'}, 'f', function()
  hop.hint_char1({ direction = directions.AFTER_CURSOR, current_line_only = false})
end, {remap = true})

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab
cccccccccccccbccccccccccccccccccccccc

Without the custom function, if you go above the "b" on the second line and hit "fb", the b on the second line is designated character a.

[smoka7]

Suggested change

	M.custom_distance_fn = nil
	M.distance_method = nil

also change the default from nil to manh_dist.

[smoka7]

Refactor the distance method to have the same signature as manh_dist.

[johnlevidy]

EDIT: had written that people would have no need for x_bias, given they're already defining a custom fn, but keeping the signatures the same is a good idea. updated.

[johnlevidy]

I wanted to place manh_distance in a module that's available already, if that's not a good place please lmk. felt reasonable since users will regularly require hint for all sorts of other things

[johnlevidy]

will remove this and inline the function call

[johnlevidy]

Sorry about the long delay, had a HW issue on my linux box and just got it back up. I think the PR should be in good shape now, please let me know if you've got any further feedback!

[smoka7]

Don't worry about the delay. I'll just have to edit some docs before merging. Thanks for the PR.