154 lines
2.6 KiB
Lua
154 lines
2.6 KiB
Lua
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-- tostring replacement that assigns ids
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local ts,id,nid,types = tostring,{},0,{table='tbl',thread='thr',userdata='uda',['function']='func'}
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tostring = function(x)
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if not x or not types[type(x)] then return ts(x) end
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if not id[x] then nid=nid+1; id[x]=types[type(x)]..'.'..nid end
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return id[x]
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end
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function a()
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return pcall( function() end )
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end
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function b()
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return pcall( function() print 'b' end )
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end
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function c()
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return pcall( function() return 'c' end )
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end
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print( pcall( a ) )
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print( pcall( b ) )
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print( pcall( c ) )
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local function sum(...)
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local s = 0
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for i,v in ipairs({...}) do
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s = s + v
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end
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return s
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end
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local function f1(n,a,b,c)
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local a = a or 0
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local b = b or 0
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local c = c or 0
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if n <= 0 then
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return a,a+b,a+b+c
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end
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return f1(n-1,a,a+b,a+b+c)
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end
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local function f2(n,...)
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if n <= 0 then
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print( " --f2, n<=0, returning sum(...)", ... )
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return sum(...)
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end
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print( " --f2, n>0, returning f2(n-1,n,...)", n-1,n,... )
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return f2(n-1,n,...)
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end
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local function f3(n,...)
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if n <= 0 then
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return sum(...)
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end
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print( " f3,n-1,n,...", f3,n-1,n,... )
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return pcall(f3,n-1,n,...)
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end
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local function all(f)
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for n=0,3 do
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t = {}
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for m=1,5 do
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print( "--f, n, unpack(t)", f, n, unpack(t) )
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print( pcall( f, n, unpack(t)) )
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t[m] = m
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end
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end
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end
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all(f1)
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all(f2)
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all(f3)
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local function f(x)
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-- tailcall to a builtin
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return math.abs(x)
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end
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local function factorial(i)
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local function helper(product, n)
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if n <= 0 then
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return product
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else
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-- tail call to a nested Lua function
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return helper(n * product, n - 1)
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end
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end
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return helper(1, i)
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end
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local result1 = factorial(5)
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print(result1)
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print(factorial(5))
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local result2 = f(-1234)
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print( result2 )
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local function fib_bad(n)
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local function helper(i, a, b)
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if i >= n then
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return a
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else
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-- not recognized by luac as a tailcall!
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local result = helper(i + 1, b, a + b)
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return result
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end
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end
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return helper(1, 1, 1)
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end
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local function fib_good(n)
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local function helper(i, a, b)
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if i >= n then
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return a
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else
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-- must be a tail call!
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return helper(i + 1, b, a + b)
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end
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end
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return helper(1, 1, 1)
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end
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local aliases = {
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['1.#INF'] = 'inf',
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['-1.#INF'] = '-inf',
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['1.#IND'] = 'nan',
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['-1.#IND'] = 'nan',
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}
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local p = function( s,e )
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print( s, e and aliases[tostring(e)] or e )
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end
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p(pcall(fib_bad, 30))
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--p((pcall(fib_bad, 25000)))
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p(pcall(fib_good, 30))
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p(pcall(fib_good, 25000))
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local function fib_all(n, i, a, b)
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i = i or 1
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a = a or 1
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b = b or 1
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if i >= n then
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return
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else
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return a, fib_all(n, i+1, b, a+b)
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end
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end
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print(fib_all(10))
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