Problem in pp.dump

[hnes]

The command line below will simply throw an error if without this commit .

$cat parse.lua
local parser = require "lua-parser.parser"
local pp = require "lua-parser.pp"

if #arg ~= 1 then
    print("Usage: parse.lua <string>")
    os.exit(1)
end

local ast, error_msg = parser.parse(arg[1], "example.lua")
if not ast then
    print(error_msg)
    os.exit(1)
end

pp.dump(ast)
os.exit(0)

$ lua parse.lua "x=2;local function x() end"
lua: /usr/share/lua/5.1/lua-parser/pp.lua:314: bad argument #3 to 'format' (string expected, got nil)
stack traceback:
        [C]: in function 'format'
        /usr/share/lua/5.1/lua-parser/pp.lua:314: in function 'dump'
        /usr/share/lua/5.1/lua-parser/pp.lua:319: in function 'dump'
        /usr/share/lua/5.1/lua-parser/pp.lua:319: in function 'dump'
        parse_str.lua:54: in main chunk
        [C]: ?

Expected output after this commit:

{
  [tag] = Block
  [pos] = 1
  [1] = {
    [tag] = Set
    [pos] = 1
    [1] = {
      [tag] = VarList
      [pos] = 1
      [1] = {
        [tag] = Id
        [pos] = 1
        [1] = x
      }
    }
    [2] = {
      [tag] = ExpList
      [pos] = 3
      [1] = {
        [tag] = Number
        [pos] = 3
        [1] = 2
      }
    }
  }
  [2] = {
    [tag] = Localrec
    [pos] = 11
    [1] = {
      [1] = {
        [tag] = Id
        [pos] = 20
        [1] = x
      }
    }
    [2] = {
      [1] = {
        [tag] = Function
        [pos] = 21
        [1] = {
        }
        [2] = {
          [tag] = Block
          [pos] = 24
        }
      }
    }
  }
}

I don't know whether this is just a little implementation problem within pp.dump or actually due to the inconsistence of the AST which generated by the parser.

Thanks a lot and all best to you. lua-parser is a pretty cool project 👍

[hnes]

Detail:

    [tag] = Localrec
    [pos] = 11
    [1] = {
      [1] = {
        [tag] = Id
        [pos] = 20
        [1] = x
      }
    }

    [tag] = Localrec
    [pos] = 11
    [1] = {
      [tag] = nil              --  <<---
      [pos] = nil              --  <<---
      [1] = {
        [tag] = Id
        [pos] = 20
        [1] = x
      }
    }

[andremm]

The command line below will simply throw an error if without this commit .

What error?
Do you mean the error is printing nil on the screen?

Thanks a lot and all best to you. lua-parser is a pretty cool project 👍

Thank you for using lua-parser! :)

[hnes]

The error is that when string.format find the '%s' in its 1st arg refers a nil value, it will simply throw an error.

> return string.format("%s[tag] = %s\n", string.rep(" ", 2), nil)
stdin:1: bad argument #3 to 'format' (string expected, got nil)
stack traceback:
        [C]: in function 'format'
        stdin:1: in main chunk
        [C]: ?
>

[hnes]

pp.lua:line:314:

function pp.dump (t, i)
  if i == nil then i = 0 end
  io.write(string.format("{\n"))
  io.write(string.format("%s[tag] = %s\n", string.rep(" ", i+2), t.tag))
  io.write(string.format("%s[pos] = %s\n", string.rep(" ", i+2), t.pos))
  for k,v in ipairs(t) do
    io.write(string.format("%s[%s] = ", string.rep(" ", i+2), tostring(k)))
    if type(v) == "table" then
      pp.dump(v,i+2)
    else
      io.write(string.format("%s\n", tostring(v)))
    end
  end
  io.write(string.format("%s}\n", string.rep(" ", i)))
end

And the error below would occur sometimes as the member "tag" and "pos" is not always present in a table which is in the AST ( Sorry for that I did not explain it clearly before).

$ lua parse.lua "x=2;local function x() end"
lua: /usr/share/lua/5.1/lua-parser/pp.lua:314: bad argument #3 to 'format' (string expected, got nil)
stack traceback:
        [C]: in function 'format'
        /usr/share/lua/5.1/lua-parser/pp.lua:314: in function 'dump'
        /usr/share/lua/5.1/lua-parser/pp.lua:319: in function 'dump'
        /usr/share/lua/5.1/lua-parser/pp.lua:319: in function 'dump'
        parse_str.lua:54: in main chunk
        [C]: ?

[andremm]

$ lua parse.lua "x=2;local function x() end"
lua: /usr/share/lua/5.1/lua-parser/pp.lua:314: bad argument #3 to 'format' (string expected, got nil)
stack traceback:
       [C]: in function 'format'
       /usr/share/lua/5.1/lua-parser/pp.lua:314: in function 'dump'
       /usr/share/lua/5.1/lua-parser/pp.lua:319: in function 'dump'
       /usr/share/lua/5.1/lua-parser/pp.lua:319: in function 'dump'
       parse_str.lua:54: in main chunk
       [C]: ?

Thanks! It looks like this is an error specific to Lua version 5.1. I just pushed a commit that should solve this problem. Can you please check whether it works?

[hnes]

No problem anymore. Thanks a lot :D 👍

[andremm]

No problem anymore. Thanks a lot :D 👍

Thanks for the report!