Function chaining

[horseinthesky]

Hello.

I'm trying to implement function node chaining with fmt node. Here is an example:

local ls = require "luasnip"
local s = ls.s
local sn = ls.sn
local t = ls.text_node

local function get_token(n)
  local hexstr = "0123456789abcdfe"
  local token = ""

  for _ = 1, n * 2 do
    local r = math.random(1, 16)
    token = token .. hexstr:sub(r, r)
  end
  return token
end

ls.add_snippets("all", {
  s(
    "user",
    fmt("{name}: {token}\n{sha}:\n  name: {name_again}\n  <<: *{group}", {
      name = i(1, "username"),
      name_again = rep(1),
      group = i(0, "group"),
      token = f(function()
        return get_token(16)
      end),
      sha = f(function(token)
        local sha256 = require "sha256"
        return sha256(token)
      end, { <?> }),
    })
  ),
})

The idea here is to pass token value (returned by function node token to function node sha. But the only thing it can accept is number of input node.

If it is possible to achieve this what should I pass as <?>? Thank you.

[L3MON4D3]

Ah, that's not possible using FunctionNodes, right now.
You could substitute the one you want to depend on with a dynamicNode that only returns a textNode (wrapped in a snippetNode).
If you find yourself needing such a node more often, you could create a wrapper around that functionality, where you only need to return a string in your function and it gets turned into a textNode automatically.

It would be possible to extend function/dynamicNode so they can depend on any nodes, not just nodes with a positiln, but I don't think that would be useful very often

[L3MON4D3]

UPDATE: From 9ef2f66 onward, functionNodes can be depended on via key_indexer! Check here for details

[leiserfg]

Why don't you just use something as fmt( "{name}: {token_and_sha}:\n name: {name_again}\n <<: *{group}", {.....}) so you calculate and return both at the same time?

[horseinthesky]

Thank you for the replies.
I've just started rewriting my ultisnips snippets from Python into Lua. I guess I'll just change token function to return token plus hash as @leiserfg proposed to keep things simple.
I don't think there is a need to implement nodes dependencies cuz LusSnips are just amazing already =)

[horseinthesky]

Hm. Don't know why it is failed:

function

local function token_and_hash(n)                           
  require "sha256"                                         
                                                           
  local hexstr = "0123456789abcdfe"                        
  local token = ""                                         
                                                           
  for _ = 1, n * 2 do                                      
    local r = math.random(1, 16)                           
    token = token .. hexstr:sub(r, r)                      
  end                                                      
                                                           
  return string.format("%s\n%s:\n  ", token, sha256(token))
end                                                        

Snippet

s(                                                                   
  "user",                                                            
  fmt("{name}: {token_and_hash}name: {name_again}\n  <<: *{group}", {
    name = i(1, "username"),                                         
    name_again = rep(1),                                             
    group = i(0, "group"),                                           
    token_and_hash = f(function()                                    
      return token_and_hash(16)                                      
    end),                                                            
  })                                                                 
),                                                                   

I get a valid string as an error:

Neovim: [LuaSnip Failed]: { "4da95a7ff1dd4227a4936f63ada1b886\n5f85b640113ef94e6b5c7b94db3705c38b3bd305aa3a54ea73ae8d1e8b3ecc13:\n  " }

[leiserfg]

Well, I don't think that's not literally your snippet isn't? 'cause sha256 is not a variable in scope.

[leiserfg]

Besides that, return a table with a raw per line instead of concatenating the strings with \n

[leiserfg]

Like

local function token_and_hash(n)
  local hexstr = "0123456789abcdfe"
  local token = ""
  for _ = 1, n * 2 do
    local r = math.random(1, 16)
    token = token .. hexstr:sub(r, r)
  end
  return { token, "token" .. token}
end

[horseinthesky]

Ok. but this is just moving the creation of str to another place. Changes nothing:

local function token_and_hash(n)                  
  require "sha256"                                
                                                  
  local hexstr = "0123456789abcdfe"               
  local token = ""                                
                                                  
  for _ = 1, n * 2 do                             
    local r = math.random(1, 16)                  
    token = token .. hexstr:sub(r, r)             
  end                                             

  return { token, sha256(token) }                 
end                                               

and

s(                                                                   
  "user",                                                            
  fmt("{name}: {token_and_hash}name: {name_again}\n  <<: *{group}", {
    name = i(1, "username"),                                         
    name_again = rep(1),                                             
    group = i(0, "group"),                                           
    token_and_hash = f(function()                                    
      local r = token_and_hash(16)                                   
      return string.format("%s\n%s:\n  ", r[1], r[2])                
    end),                                                            
  })                                                                 
),                                                                   

And yes. sha256 function is in another module (I am requireing it in token_and_hash function above).

I don't understand LuaSnip output and what is wrong.

[leiserfg]

1. You are requiring the lua file, but that does not introduce a local (unless sha256 the module is declaring a global sha256 which will work but is an antipattern)
2. The function passed to f has to return a string with a single line of text (without \n) or a table of strings (one per line).

[leiserfg]

I just replaced your sha256 call with "token" .. token in my example cause I don't have your sha256 lib, but the rest is the same and should work if sha256 is (as I said) exposing a global

[horseinthesky]

It deffinately should but it is actually not. Guided by 2) I am not allowed to use \n in return value, am I?

Is there a way to get the following structure:

username: 00f2926999262d3e08b3ce818bcf1fe4
78959e829261d2fbf804fa783e0cbb5c6af56bb5d7398f683d2ce3d5a6e11d51:
  name: username
    <<: *group

?

[leiserfg]

Sure you can:

local function sha256(secret)
    return "chachacha" .. secret
end


local function token_and_hash(n)
  local hexstr = "0123456789abcdfe"
  local token = ""
  for _ = 1, n * 2 do
    local r = math.random(1, 16)
    token = token .. hexstr:sub(r, r)
  end
  return { token, sha256(token) .. ":", '' }
end

ls.add_snippets(nil, {
  all = {
s(
  "user",
  fmt("{name}: {token_and_hash}name: {name_again}\n  <<: *{group}", {
    name = i(1, "username"),
    name_again = rep(1),
    group = i(0, "group"),
    token_and_hash = f(function()
      return token_and_hash(16)
    end),
  })
)
}

[horseinthesky]

Aha. So each value from the table ( or a table of strings (one per line)) is put on a new line under the hood.
Works great. Thanks again!