Module:User:Cscott/compat explained

return (functionlocal builders = local function register(name, f) builders[name] = fendregister('advent.compat', function(myrequire)-- Compatibility functions-- (Things present in Lua 5.3 that are missing in Lua 5.1)local compat =

local string = myrequire('string')local table = myrequire('table')

function compat.len(v) -- the length metamethod is only available starting in Lua 5.2 if type(v)

'table' then local mt = getmetatable(v) if mt ~= nil then local len = mt.__len if len ~= nil then return len(v) end end end return #vend

function compat.combineBytes(msb, lsb) -- (msb << 8) | lsb return (msb * 256) + lsbend

function compat.splitBytes(u16) -- u16 >> 8, u16 & 0xFF local lsb = math.fmod(u16, 256) local msb = (u16 - lsb) / 256 return msb, lsbend

function compat.rshift(x, disp) -- x >> disp return math.floor(x/(2^disp))end

function compat.idiv(a, b) local tya, tyb = type(a), type(b) if tya ~= 'number' or tyb ~= 'number' then local op = nil local mt = getmetatable(a) if mt ~= nil then op = mt.__idiv end if op

nil then mt = getmetatable(b) if mt ~= nil then op = mt.__idiv end end if op ~= nil then return op(a, b) end end return math.floor(a / b)end

function compat.utf8codes(s) local len = #s local f = function(state, _) local pos = state.nextpos if pos > len then return nil, nil end local c1 = string.byte(s, pos) if c1 <= 0x7F then state.nextpos = pos + 1 return pos, c1 end local c2 = string.byte(s, pos + 1) if c1 <= 0xDF then state.nextpos = pos + 2 return pos, ((c1 % 0x20) * 0x40) + (c2 % 0x40) end local c3 = string.byte(s, pos + 2) if c1 <= 0xEF then state.nextpos = pos + 3 return pos, (((c1 % 0x10) * 0x40) + (c2 % 0x40)) * 0x40 + (c3 % 0x40) end local c4 = string.byte(s, pos + 3) if c1 <= 0xF7 then state.nextpos = pos + 4 return pos, ((((c1 % 0x08) * 0x40) + (c2 % 0x40)) * 0x40 + (c3 % 0x40)) * 0x40 + (c4 % 0x40) end error("bad utf-8") end return f,, 0end

function compat.utf8char(...) -- utf8.char(c) local result = for _,c in ipairs do local s if c <= 0x7F then s = string.char(c) else local c1 = c % 0x40 local cN = (c - c1) / 0x40 if c <= 0x7FF then s = string.char(cN + 0xC0, c1 + 0x80) else local c2 = cN % 0x40 cN = (cN - c2) / 0x40 if c <= 0xFFFF then s = string.char(cN + 0xE0, c2 + 0x80, c1 + 0x80) else local c3 = cN % 0x40 cN = (cN - c3) / 0x40 if c <= 0x10FFFF then s = string.char(cN + 0xF0, c3 + 0x80, c2 + 0x80, c1 + 0x80) else error end end end end table.insert(result, s) end return table.concat(result)end

-- unpack is a global function for Lua 5.1, otherwise use table.unpackcompat.unpack = table.unpack or function(tbl, i, j) local unpack = rawget(_G, "unpack") -- we also need to use compat.len to get the length of this table! if i

nil then i = 1 end if j

nil then j = compat.len(tbl) end return unpack(tbl, i, j)end-- table.pack was added in Lua 5.2compat.pack = table.pack or function(...) local t = t.n = select("#",...) return tend

-- table.move was added in Lua 5.3compat.move = table.move or function(a1, f, e, t, a2) if a2

nil then a2 = a1 end local tmp = for i=f,e do tmp[1+i-f] = a1[i] end for i=f,e do a2[t+i-f] = tmp[1+i-f] end return a2end

return compat

end)

local modules = modules['bit32'] = require('bit32')modules['string'] = require('string')modules['strict'] = modules['table'] = require('table')local function myrequire(name) if modules[name]