Lua implementation of tostring(table) docs for OpenComputers

docsBuilder.lua

local serialization = require('serialization')
local serialize, deserialize = serialization.serialize, serialization.deserialize

local stringBuilder = require('stringBuilder')
local MAX_LINES = 10

local docsBuilder = {}

docsBuilder.MAX_LINES = MAX_LINES

function formatValueEntry(value)
  local sb = stringBuilder()
  local mspace = ''
  for s in string.gmatch(value, '[^\r\n]+') do
    sb.append(mspace .. s)
    mspace = '\n '
  end
  return sb.value
end

function isShortKeyAble(key)
  if type(key) ~= 'string' then return false end
  if string.match(key, '[0-9].*') == key then return false end
  if string.match(key, '[a-zA-Z0-9_]+') == key then return true end
  return false
end

return setmetatable(docsBuilder, {
  __call = function(_, obj, maxLines)
    assert(type(obj) == 'table', 'bad argument #1 (table expected, got ' .. type(obj) .. ')')
    assert(
      type(maxLines) == 'number' or type(maxLines) == 'boolean' or maxLines == nil,
      'bad argument #2 (number, boolean or nil expected, got ' .. type(maxLines) .. ')'
    )

    maxLines = maxLines or MAX_LINES

    if type(maxLines) == 'boolean' then
      maxLines = maxLines and math.huge or MAX_LINES
    else
      assert(maxLines > 0, 'bad argument #2 (nuber greater than 0 expected)')
    end

    local builder = {}

    return setmetatable(builder, {
     __tostring = function()
       local sb = stringBuilder()

       local lineCount = 1
       sb.append('{')

       local i = 0
       local mspace = ''

       function appendMember(name, value)
         if i ~= #obj and lineCount ~= 1 then
           sb.append(',\n')
         end

         local shortKey = isShortKeyAble(name)
         local newEntry
         if shortKey then
           newEntry = mspace .. name .. '=' .. formatValueEntry(value)
         else
           if type(name) == 'boolean' or type(name) == 'number' then
             newEntry = mspace .. '[' .. name .. ']=' .. formatValueEntry(value)
           else
             newEntry = mspace .. '["' .. name .. '"]=' .. formatValueEntry(value)
           end
         end

         if lineCount == 1 then
           mspace = shortKey and '\x20' or '\x20\x20'
         end

         local lines = (function()
           local t = {}
           local c = 0
           for v in string.gmatch(newEntry, '[^\r\n]+') do
             c = c + 1
             t[c] = v
           end
           return t
         end)()

         local lineNumber = 0
         while lineCount <= maxLines do
           lineNumber = lineNumber + 1

           local line = lines[lineNumber]
           if line == nil then break end
           sb.append(line)

           if lineNumber < #lines then
             sb.append('\n')
           end

           lineCount = lineCount + 1
         end
       end

       for memberName, member in pairs(obj) do
         i = i + 1

         if lineCount > maxLines then break end

         local docEntry = builder[memberName]

         if docEntry == true or docEntry == nil then
           if type(member) == 'table' then
             appendMember(memberName, serialize(member, maxLines))
           else
             appendMember(memberName, tostring(member))
           end
         elseif type(docEntry) == 'string' then
           appendMember(memberName, docEntry)
         end
       end

       if lineCount > maxLines then
         sb.append(',\n...')
       else
         sb.append('}')
       end

       return sb.value
     end
    })
  end
})

stringBuilder.lua

local stringBuilder = {}

local keyBlacklist = {internal = true}

return setmetatable({}, {
  __call = function()
    local t = {}

    local props = {
      value = function()
        return table.concat(t)
      end
    }

    local methods = {
      append = function(...)
        for _, v in ipairs({...}) do
          table.insert(t, v)
        end
      end,
      remove = function(n)
        return table.remove(t, n)
      end,
      compile = function(...)
        return table.concat(t, ...)
      end,
      len = function()
        return #t
      end
    }

    local builder = {internal = { t = t }}

    return setmetatable({}, {
      __index = function(_, key)
        if builder[key] then return builder[key] end
        if props[key] then return props[key]() end
        return methods[key]
      end,
      __newindex = function(_, key, value)
        builder[key] = value
      end,
      __pairs = function()
        local prevKey
        local enum = 'builder'
        local enumProps, enumMethods, enumBuilder

        enumProps = function()
          local propKey, propValue = next(props, prevKey)

          if propKey then
            prevKey = propKey
            return propKey, propValue
          end

          prevKey = nil
          enum = 'methods'
          return enumMethods()
        end

        enumMethods = function()
          local methodKey, methodValue = next(methods, prevKey)

          if methodKey then
            prevKey = methodKey
            return methodKey, methodValue
          end

          prevKey = nil
          enum = 'builder'
          return -- return nothing (terminates the iterator)
        end

        enumBuilder = function()
          local builderKey, builderValue = next(builder, prevKey)
          prevKey = builderKey

          while keyBlacklist[builderKey] ~= nil do
            builderKey, builderValue = next(builder, prevKey)
            prevKey = builderKey
          end

          if builderKey ~= nil then return builderKey, builderValue end
          prevKey = nil
          enum = 'props'
          return enumProps()
        end

        return function()
          if enum == 'builder' then return enumBuilder() end
          if enum == 'props' then return enumProps() end
          if enum == 'methods' then return enumMethods() end
          error('unexpected stringBuilder iterator error')
        end
      end,
      __len = function(self)
        local count = 0
        for _ in pairs(self) do count = count + 1 end
        return count
      end
    })
  end
})