-- $Id: goto.lua,v 1.11 2014/12/26 17:20:53 roberto Exp $ collectgarbage() local function errmsg (code, m) local st, msg = load(code) assert(not st and string.find(msg, m)) end -- cannot see label inside block errmsg([[ goto l1; do ::l1:: end ]], "label 'l1'") errmsg([[ do ::l1:: end goto l1; ]], "label 'l1'") -- repeated label errmsg([[ ::l1:: ::l1:: ]], "label 'l1'") -- undefined label errmsg([[ goto l1; local aa ::l1:: ::l2:: print(3) ]], "local 'aa'") -- jumping over variable definition errmsg([[ do local bb, cc; goto l1; end local aa ::l1:: print(3) ]], "local 'aa'") -- jumping into a block errmsg([[ do ::l1:: end goto l1 ]], "label 'l1'") errmsg([[ goto l1 do ::l1:: end ]], "label 'l1'") -- cannot continue a repeat-until with variables errmsg([[ repeat if x then goto cont end local xuxu = 10 ::cont:: until xuxu < x ]], "local 'xuxu'") -- simple gotos local x do local y = 12 goto l1 ::l2:: x = x + 1; goto l3 ::l1:: x = y; goto l2 end ::l3:: ::l3_1:: assert(x == 13) -- long labels do local prog = [[ do local a = 1 goto l%sa; a = a + 1 ::l%sa:: a = a + 10 goto l%sb; a = a + 2 ::l%sb:: a = a + 20 return a end ]] local label = string.rep("0123456789", 40) prog = string.format(prog, label, label, label, label) assert(assert(load(prog))() == 31) end -- goto to correct label when nested do goto l3; ::l3:: end -- does not loop jumping to previous label 'l3' -- ok to jump over local dec. to end of block do goto l1 local a = 23 x = a ::l1::; end while true do goto l4 goto l1 -- ok to jump over local dec. to end of block goto l1 -- multiple uses of same label local x = 45 ::l1:: ;;; end ::l4:: assert(x == 13) if print then goto l1 -- ok to jump over local dec. to end of block error("should not be here") goto l2 -- ok to jump over local dec. to end of block local x ::l1:: ; ::l2:: ;; else end -- to repeat a label in a different function is OK local function foo () local a = {} goto l3 ::l1:: a[#a + 1] = 1; goto l2; ::l2:: a[#a + 1] = 2; goto l5; ::l3:: ::l3a:: a[#a + 1] = 3; goto l1; ::l4:: a[#a + 1] = 4; goto l6; ::l5:: a[#a + 1] = 5; goto l4; ::l6:: assert(a[1] == 3 and a[2] == 1 and a[3] == 2 and a[4] == 5 and a[5] == 4) if not a[6] then a[6] = true; goto l3a end -- do it twice end ::l6:: foo() -------------------------------------------------------------------------------- -- testing closing of upvalues local debug = require 'debug' local function foo () local t = {} do local i = 1 local a, b, c, d t[1] = function () return a, b, c, d end ::l1:: local b do local c t[#t + 1] = function () return a, b, c, d end -- t[2], t[4], t[6] if i > 2 then goto l2 end do local d t[#t + 1] = function () return a, b, c, d end -- t[3], t[5] i = i + 1 local a goto l1 end end end ::l2:: return t end local a = foo() assert(#a == 6) -- all functions share same 'a' for i = 2, 6 do assert(debug.upvalueid(a[1], 1) == debug.upvalueid(a[i], 1)) end -- 'b' and 'c' are shared among some of them for i = 2, 6 do -- only a[1] uses external 'b'/'b' assert(debug.upvalueid(a[1], 2) ~= debug.upvalueid(a[i], 2)) assert(debug.upvalueid(a[1], 3) ~= debug.upvalueid(a[i], 3)) end for i = 3, 5, 2 do -- inner functions share 'b'/'c' with previous ones assert(debug.upvalueid(a[i], 2) == debug.upvalueid(a[i - 1], 2)) assert(debug.upvalueid(a[i], 3) == debug.upvalueid(a[i - 1], 3)) -- but not with next ones assert(debug.upvalueid(a[i], 2) ~= debug.upvalueid(a[i + 1], 2)) assert(debug.upvalueid(a[i], 3) ~= debug.upvalueid(a[i + 1], 3)) end -- only external 'd' is shared for i = 2, 6, 2 do assert(debug.upvalueid(a[1], 4) == debug.upvalueid(a[i], 4)) end -- internal 'd's are all different for i = 3, 5, 2 do for j = 1, 6 do assert((debug.upvalueid(a[i], 4) == debug.upvalueid(a[j], 4)) == (i == j)) end end -------------------------------------------------------------------------------- -- testing if x goto optimizations local function testG (a) if a == 1 then goto l1 error("should never be here!") elseif a == 2 then goto l2 elseif a == 3 then goto l3 elseif a == 4 then goto l1 -- go to inside the block error("should never be here!") ::l1:: a = a + 1 -- must go to 'if' end else goto l4 ::l4a:: a = a * 2; goto l4b error("should never be here!") ::l4:: goto l4a error("should never be here!") ::l4b:: end do return a end ::l2:: do return "2" end ::l3:: do return "3" end ::l1:: return "1" end assert(testG(1) == "1") assert(testG(2) == "2") assert(testG(3) == "3") assert(testG(4) == 5) assert(testG(5) == 10) -------------------------------------------------------------------------------- print'OK'