Trying to make a generic recursive node list

[danielo515]

Hello, inspired by the infinite recursive snippet from the wiki, I tried to make a generic version that I can use like a library in all my snippets. however, I'm failing to achieve that goal. Maybe you can take a look at my code and tell me what is wrong.
Thanks!

here is the code:

local rec_ls
rec_ls = function(pos, _nodes)
  assert(type(_nodes) == "table", "List of nodes must be a table")
  local nodes = vim.list_extend({ t "" }, _nodes)
  return function()
    table.insert(nodes, d(pos, rec_ls(pos, _nodes), {}))
    vim.pretty_print(nodes)
    return sn(nil, {
      c(1, {
        -- important!! Having the sn(...) as the first choice will cause infinite recursion.
        t { "" },
        -- The same dynamicNode as in the snippet (also note: self reference).
        sn(nil, nodes),
      }),
    })
  end
end

The used like this:

  s(
    { trig = "ext", dscr = "Extern class", regTrig = false },

    fmt(
      [[ extern class {} {{
              {}
              {}
              }}
    ]],
      {
        i(1),
        d(2, rec_ls(3, fmt(" static function {}({}):{}; ", { i(1), i(2), i(0) })), {}),
      }
    )
  ),

[L3MON4D3]

I think tye issue is that the _nodes are reused in the different "stages" of t€hat snippet. Try passing _nodes:copy() to the recursive call instead.
But also generally, I'd advise you to follow the warning in the wiki, use that dynamicNode-extension, it is a bit more complicated, but worth it imo :D

[danielo515]

Do you have a suggested implementation? I'm afraid I am a bit stuck

[L3MON4D3]

Here, this works for me:

ls.setup_snip_env()

local rec_ls
rec_ls = function(pos, _nodes)
  assert(type(_nodes) == "table", "List of nodes must be a table")
  -- flat-copy nodes, otherwise we'd insert `d(...)` in every iteration.
  local nodes = {unpack(_nodes)}
  return function()
    table.insert(nodes, d(pos, rec_ls(pos, _nodes), {}))
    return sn(nil, {
      c(1, {
        -- important!! Having the sn(...) as the first choice will cause infinite recursion.
        t { "" },
        -- deep copy of nodes here.
        sn(nil, nodes):copy(),
      }),
    })
  end
end

ls.snip_expand(s(
    { trig = "ext", dscr = "Extern class", regTrig = false },

    fmt(
      [[ extern class {} {{
              {}
              {}
              }}
    ]],
      {
        i(1),
        d(2, rec_ls(3, fmt(" static function {}({}):{}; ", { i(1), i(2), i(0) })), {}),
        i(3)
      }
    )
  ))

This could be improved by appending the d(...) only once, and then reusing that table. I guess you'd need another function to make that work.
But also, I'd like to recommend the different approach again, it will result in a more solid snippet imo 😅

[danielo515]

Thank you for looking into it.
That at least "compiles", but then I get this error when expanding the option choice

E5108: Error executing lua: ...ite/pack/packer/start/LuaSnip/lua/luasnip/nodes/util.lua:24: attempt to get length of local 'position_so_far' (a nil value)
stack traceback:
	...ite/pack/packer/start/LuaSnip/lua/luasnip/nodes/util.lua:24: in function 'init_insert_positions'
	...k/packer/start/LuaSnip/lua/luasnip/nodes/dynamicNode.lua:161: in function 'update'
	...k/packer/start/LuaSnip/lua/luasnip/nodes/dynamicNode.lua:342: in function 'update_restore'
	.../pack/packer/start/LuaSnip/lua/luasnip/nodes/snippet.lua:825: in function 'update_restore'
	...ck/packer/start/LuaSnip/lua/luasnip/nodes/choiceNode.lua:254: in function 'no_region_check_wrap'
	...rvim/site/pack/packer/start/LuaSnip/lua/luasnip/init.lua:361: in function 'change_choice'
	/Users/danielo/.config/lvim/lua/user/plugins/cmp-config.lua:177: in function 'on_keymap'
	...unarvim/site/pack/packer/start/nvim-cmp/lua/cmp/core.lua:145: in function 'callback'
	...site/pack/packer/start/nvim-cmp/lua/cmp/utils/keymap.lua:133: in function <...site/pack/packer/start/nvim-cmp/lua/cmp/utils/keymap.lua:127>
E5108: Error executing lua: ...site/pack/packer/start/LuaSnip/lua/luasnip/util/util.lua:505: attempt to perform arithmetic on a nil value
stack traceback:
	...site/pack/packer/start/LuaSnip/lua/luasnip/util/util.lua:505: in function 'pos_sub'
	...ck/packer/start/LuaSnip/lua/luasnip/nodes/choiceNode.lua:223: in function 'no_region_check_wrap'
	...rvim/site/pack/packer/start/LuaSnip/lua/luasnip/init.lua:361: in function 'change_choice'
	/Users/danielo/.config/lvim/lua/user/plugins/cmp-config.lua:177: in function 'on_keymap'
	...unarvim/site/pack/packer/start/nvim-cmp/lua/cmp/core.lua:145: in function 'callback'
	...site/pack/packer/start/nvim-cmp/lua/cmp/utils/keymap.lua:133: in function <...site/pack/packer/start/nvim-cmp/lua/cmp/utils/keymap.lua:127>

Maybe I need a newer version of LuaSnip?

But also, I'd like to recommend the different approach again, it will result in a more solid snippet imo 😅

I took a look at it, and it seems to require some global keybindings. Something that I hate about neovim and that I'm trying to avoid or at least reduce, is that the editor does not have any sense of context, you have to keep it in your head. I'm on a snippet? Then bindigs A to B. The snippet is a choice snippet? Then bindings C to E and if this is an ever expanding snippet, then bindings X to Z. Apply that to all the possible plugins and situations you have in your daily coding and you get an explosion of things to remember. I prefer the editor to remember those and do different things based on the context. If you have any method to reduce this mental burden I will be more than happy to try it.

[L3MON4D3]

Maybe I need a newer version of LuaSnip?

Mhm, I don't think that's it, we didn't change anything there for quite a while.
Very weird.. could you try :luafile %ing the code I sent?

[L3MON4D3]

I took a look at it, and it seems to require some global keybindings. Something that I hate about neovim and that I'm trying to avoid or at least reduce, is that the editor does not have any sense of context, you have to keep it in your head. I'm on a snippet? Then bindigs A to B. The snippet is a choice snippet? Then bindings C to E and if this is an ever expanding snippet, then bindings X to Z. Apply that to all the possible plugins and situations you have in your daily coding and you get an explosion of things to remember. I prefer the editor to remember those and do different things based on the context. If you have any method to reduce this mental burden I will be more than happy to try it.

I can see your point regarding mental overhead, I guess the only solution is getting used to it :/

[danielo515]

Ah, OK. I didn't know that clone performs a deep clone. Is that a feature of luasnip? Or is plain Lua? El dom., 11 dic. 2022 13:30, L3MON4D3 ***@***.***> escribió:

…

Oh, I was referring to a deep copy, with a shallow copy (which afaik list_extend performs) there might still be the same exact node multiple times inside the snippet, which can cause all sorts of issues. local nodes = _nodes:copy() should do it — Reply to this email directly, view it on GitHub <#689 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AARKJWL36U5IYBLOJUXOM6TWMXCNRANCNFSM6AAAAAAS2ZKHMA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[L3MON4D3]

Feature of luasnip, but all that's happening behind the scenes is vim.deepcopy() (though you'd better use the copy-method, it's more future-proof in case we have to make changes there)