Error processing escape character in strings

[foul11]

Very simple code for demo:

local parser = require('dumbParser')

local ast = parser.parse('print("\\x00")') -- passed string: print("\x00")
--local ast = parser.parseExpression('print("\\x00")') -- same thing
--local ast = parser.parseFile('test.lua') -- same thing

parser.printTree(ast) -- toLua gives the same effect
                      -- lua51:        ... ARG1 literal (string="x00") / Wrong.
                      -- lua53/luajit: ... ARG1 literal (string="{NUL}") / OK.

local ast = parser.parse('print("\\\\x00")') -- passed string: print("\\x00") / OK
--local ast = parser.parse('print("\\0000")') -- passed string: print("\0000") / OK
--local ast = parser.parse('print("\\1000")') -- passed string: print("\1000") / OK

parser.printTree(ast) -- toLua gives the same effect
                      -- lua51:        ... ARG1 literal (string="\x00") / OK.
                      -- lua53/luajit: ... ARG1 literal (string="\x00") / OK.

This affects the recording of escape characters.

• In Lua5.1 they turn into plain text.
• In Lua5.3 or Luajit there is no such problem.