fix: prevent conds lambda from caching the first length parameter

[ribru17]

Problem:

I faced this issue when trying to write a simple rule for a block comment:

      npairs.add_rule(
        Rule('/**', '  */')
        :with_pair(cond.not_after_regex('.-%*/', -1))
        :set_end_pair_length(3)
      )

This rule kept failing and I thought I was going insane or just dumb but it turns out due to the odd nature of how variables are captured in lua. The first time that the not_after_regex function is run it instantiates the function to be returned with the cached value of length, and this is essentially always going to be the referenced value from within the returned function. I.e.:

cond.not_after_regex = function(regex, length)
    length = length or 1
    if not regex then
        return cond.none()
    end
    ---@param opts CondOpts
    return function(opts)
        log.debug('not_after_regex')
        if length < 0 then
            length = #opts.line
            -- LENGTH and #OPTS.LINE ARE NOT ALWAYS EQUAL HERE
        end
        local str = utils.text_sub_char(opts.line, opts.col, length)
        if str:match(regex) then
            return false
        end
    end
end

This is what caused my rule to fail. Instantiation a new local variable from within the returned lambda function fixes this issue in my testing, and I implemented it in the other regex related conditions as well.

cond.not_after_regex = function(regex, length)
    length = length or 1
    if not regex then
        return cond.none()
    end
    ---@param opts CondOpts
    return function(opts)
        log.debug('not_after_regex')
        local captured_length = length
        if captured_length < 0 then
            captured_length = #opts.line
            -- WORKS
        end
        local str = utils.text_sub_char(opts.line, opts.col, captured_length)
        if str:match(regex) then
            return false
        end
    end
end

Really hope this can get merged, thank you

[ribru17]

Here is a simpler example I made:

local function test(initial)
  initial = initial or 1
  return function(next)
    if initial < 0 then
      initial = next
    end
    print(initial)
  end
end

-- should always run `f` with initial = -1 (but does not)
local f = test(-1)

f(3) -- should print 3, prints 3

-- initial is now 3

f(7) -- should print 7, prints 3

[windwp]

I think we should remove the length variable .
Can you remove it

[ribru17]

done 👍

[ribru17]

Would you mind telling me how to run the tests on my local machine? When I run make test many tests fail when they shouldn't, saying module 'nvim-surround' not found

[windwp]

nvim-autopairs/tests/minimal.vim

Line 1 in e8f7dd7

set rtp +=.

the rtp=. is nvim-autopairs folder

You need put nvim-autopairs and plenary and nvim treesitter in same folder.

Then you goto inside nvim-autopairs folder and run
make test

I will check that soon

[ribru17]

Realized one last bug in my fix. If this doesn't work I'll quit finally and let you take a look. still couldn't get tests running sadly, sorry

[windwp]

Thanks 😍

[windwp]

hi i just thinking about it then i add length param back.
Removing it would make many users to update their config for custom rules, which is something I would like to avoid.

so if you still need to add -1 to set length on regex