A nice string conversion module for tables

LICENSE.md

This is free and unencumbered software released into the public domain.

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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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table_to_string.lua

--- Pro tip: You can also use this as the actual string conversion used
--- by a table using metaprogramming, like this:
--[[
local table_to_string = require("table_to_string")

local mytable, mt = {}, {}
mt.__tostring = table_to_string
setmetatable(mytable, mt)
--]]

---@param s string
---@return string, integer
local function string_escape(s)
	return s:gsub("\\", [[\\]])
		:gsub("\a", [[\a]])
		:gsub("\b", [[\b]])
		:gsub("\f", [[\f]])
		:gsub("\n", [[\n]])
		:gsub("\r", [[\r]])
		:gsub("\t", [[\t]])
		:gsub("\v", [[\v]])
		:gsub("\"", [[\"]])
		:gsub("\'", [[\']])
end

---@param str string
---@param n number
---@return string
local function string_multiply(str, n)
	if n <= 0 then
		return ""
	end

	local outs = ""
	local floor = math.floor(n)
	local point = n - floor

	for i = 0, n do
		outs = outs..str
	end

	if point > 0 then
		local len = #str * floor
		outs = outs..str:sub(1, math.floor(len))
	end

	return outs
end

---@param t table
---@param indent? string
---@param depth? integer
---@return string
local function table_to_string(t, indent, depth)
	indent = indent or "    "
	depth = depth or 0
	local bracket_indent = string_multiply(indent, depth)
	local full_indent = bracket_indent..indent

	local outs = bracket_indent.."{\n"

	for k, v in pairs(t) do
		local tv = type(v)
		local tk = type(k)

		if tv == "table" then
			outs = outs..table_to_string(v, indent, depth + 1).."\n"
		else
			if tk == "string" then
				k = '"'..string_escape(k)..'"'
			end
			if tv == "string" then
				v = '"'..string_escape(v)..'"'
			end

			if tk == "function" or tk == "thread" or tk == "userdata" then
				k = '[['..tostring(k)..']]'
			end
			if tv == "function" or tv == "thread" or tv == "userdata" then
				v = '[['..tostring(v)..']]'
			end

			outs = ("%s%s[%s] = %s,\n"):format(outs, full_indent, k, v)
		end
	end

	return outs..bracket_indent.."}"
end

return table_to_string