Simple Pure Lua Interpreter/Compiler

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#1

The name for this interpreter… (shit code)

local function split(str, sep) -- string.split does not exist in Pure Lua
	local fields = {}
	local pattern = string.format("([^%s]+)", sep or " ")
	str:gsub(pattern, function(c) fields[#fields+1] = c end)
	return fields
end

local function interpreter(code_str)
	local lines = {}
	local stack = {}
	local constants = {}
	for line in code_str:gmatch("[^\r\n]+") do
		table.insert(lines, line)
	end

	for stackline, line in ipairs(lines) do
		local command, argument = line:match("^(%w+)%s*(.*)$")
		local contents = split(argument, " ")

		if command == "PRINT" then
			if not stack[stackline] then
				stack[stackline] = {["PRINT"] = {}}
			end
			local printOrder = 1
			for _, constant in ipairs(contents) do
				local found = false
				for i = 1, #stack do
					if stack[i]["LOCAL"][constant] then
						stack[stackline]["PRINT"][printOrder] = {
							name = constants[constant] or constant,
							value = stack[i]["LOCAL"][constant]
						}
						found = true
						printOrder = printOrder + 1
						break
					end
				end
				if not found then
					print("Undefined variable or constant: " .. constant)
				end
			end
		elseif command == "END" then
			break
		elseif command == "LOCAL" then
			local value, content = contents[1], contents[2]
			if not stack[stackline] then
				stack[stackline] = {["LOCAL"] = {}}
			end
			stack[stackline]["LOCAL"][value] = content
			constants[value] = value -- Store the constant name
		else
			print(command .. ":" .. stackline .. ": Incomplete statement: expected assignment or a function call")
			stack = nil
			break
		end
	end
	return stack
end

local function execute_stack(stack)
	if not stack then
		return
	end

	for stackline, entry in ipairs(stack) do
		if entry["PRINT"] then
			for _, item in ipairs(entry["PRINT"]) do
				print(item.name)
				print(item.value)
				print()

			end
		end
	end
	print(stack)
end

local code_str = [[
LOCAL HELLO GUYS
LOCAL THIS IS
LOCAL A TEST

PRINT HELLO THIS A
]]

local stack = interpreter(code_str)

execute_stack(stack)

-- Expected Output:
-- HELLO
-- GUYS

-- THIS 
-- IS

-- A
-- TEST
-- (stack table)
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