```
for _, m in ipairs({'', 'k', 'kv', 'v'}) do
print('test', m)
a = {}; setmetatable(a, {__mode = m});
a[1], a[2], a[3] = {}, {}, {};
for k, v in pairs(a) do
print(k, v)
end
end
print('ok')
```
```
t = {}
t.__lt = function (a,b,c)
collectgarbage()
assert(c == nil)
if type(a) == 'table' then a = a.x end
if type(b) == 'table' then b = b.x end
return a<b, "dummy"
end
function Op(x) return setmetatable({x=x}, t) end
local function test ()
assert(not(Op(1)<Op(1)) and (Op(1)<Op(2)) and not(Op(2)<Op(1)))
assert(not(1 < Op(1)) and (Op(1) < 2) and not(2 < Op(1)))
assert(not(Op('a')<Op('a')) and (Op('a')<Op('b')) and not(Op('b')<Op('a')))
assert(not('a' < Op('a')) and (Op('a') < 'b') and not(Op('b') < Op('a')))
assert((Op(1)<=Op(1)) and (Op(1)<=Op(2)) and not(Op(2)<=Op(1)))
assert((Op('a')<=Op('a')) and (Op('a')<=Op('b')) and not(Op('b')<=Op('a')))
assert(not(Op(1)>Op(1)) and not(Op(1)>Op(2)) and (Op(2)>Op(1)))
assert(not(Op('a')>Op('a')) and not(Op('a')>Op('b')) and (Op('b')>Op('a')))
assert((Op(1)>=Op(1)) and not(Op(1)>=Op(2)) and (Op(2)>=Op(1)))
assert((1 >= Op(1)) and not(1 >= Op(2)) and (Op(2) >= 1))
assert((Op('a')>=Op('a')) and not(Op('a')>=Op('b')) and (Op('b')>=Op('a')))
assert(('a' >= Op('a')) and not(Op('a') >= 'b') and (Op('b') >= Op('a')))
end
test()
```
```
-- bug since 2.5 (C-stack overflow)
do
local function f (size)
local s = string.rep("a", size)
local p = string.rep(".?", size)
return pcall(string.match, s, p)
end
local r, m = f(80)
assert(r and #m == 80)
r, m = f(200000)
assert(not r and string.find(m, "too complex"), tostring(r)..", "..tostring(m))
end
```
```
do -- new (5.3.3) semantics for empty matches
assert(string.gsub("a b cd", " *", "-") == "-a-b-c-d-")
local res = ""
local sub = "a \nbc\t\td"
local i = 1
for p, e in string.gmatch(sub, "()%s*()") do
res = res .. string.sub(sub, i, p - 1) .. "-"
i = e
end
assert(res == "-a-b-c-d-")
end
```
```
do -- testing table library with metamethods
local function test (proxy, t)
for i = 1, 10 do
table.insert(proxy, 1, i)
end
assert(#proxy == 10 and #t == 10, tostring(#proxy)..'; '..tostring(#t))
for i = 1, 10 do
assert(t[i] == 11 - i)
end
table.sort(proxy)
for i = 1, 10 do
assert(t[i] == i and proxy[i] == i, i..': '..tostring(proxy[i])..'; '..tostring(t[i]))
end
assert(table.concat(proxy, ",") == "1,2,3,4,5,6,7,8,9,10")
for i = 1, 8 do
assert(table.remove(proxy, 1) == i)
end
assert(#proxy == 2 and #t == 2)
local a, b, c = table.unpack(proxy)
assert(a == 9 and b == 10 and c == nil)
end
-- all virtual
local t = {}
local proxy = setmetatable({}, {
__len = function () return #t end,
__index = t,
__newindex = t,
})
test(proxy, t)
-- only __newindex
local count = 0
t = setmetatable({}, {
__newindex = function (t,k,v) count = count + 1; rawset(t,k,v) end})
test(t, t)
assert(count == 10) -- after first 10, all other sets are not new
-- no __newindex
t = setmetatable({}, {
__index = function (_,k) return k + 1 end,
__len = function (_) return 5 end})
assert(table.concat(t, ";") == "2;3;4;5;6")
end
function check (a, f)
f = f or function (x,y) return x<y end;
for n = #a, 2, -1 do
local cmp = f(a[n], a[n-1])
if cmp then print(tostring(a)..'\n'..n..': "'..tostring(a[n])..'" < "'..tostring(a[n-1])..'"') end
assert(not cmp)
end
end
for b = 1, 2 do
a = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep",
"Oct", "Nov", "Dec"}
if b == 2 then a[15] = 'Aaa' a[14] = 'Iii' a[13] = 'Mmm' end
print(#a)
table.sort(a)
check(a)
end
```
