Loops/With multiple ranges: Difference between revisions

=={{header|Lua}}==

Not directly supported, i.e. no ''true'' multi-range loops, but.. all that's really needed is a helper function to populate the list of values, aiming to specify the ranges with a syntax as-close-as-manageable to mimic that given in task description (iteration is then trivial):

<lang lua>-- support:

function T(t) return setmetatable(t, {__index=table}) end

table.range = function(t,a,b,c) local s=T{} for i=a,b,c or 1 do s[#s+1]=i end return s end

table.clone = function(t) local s=T{} for k,v in ipairs(t) do s[k]=v end return s end

table.chain = function(t,u) local s=t:clone() for i=1,#u do s[#s+1]=u[i] end return s end

unpack = unpack or table.unpack -- polyfill 5.2 vs 5.3

-- impl:

-- Multi-Range-Loop

-- param: table of tables of range specs

-- return: iterator over the chain of all ranges

function mrl(tt)

local s=T{}

for _,t in ipairs(tt) do s=s:chain(T{}:range(unpack(t))) end

return ipairs(s)

end

-- demo:

prod,sum,x,y,z,one,three,seven = 1,0,5,-5,-2,1,3,7

for _,j in mrl{

{ -three, 3^3, three },

{ -seven, seven, x },

{ 555, 550-y },

{ 22, -28, -three },

{ 1927, 1939 },

{ x, y, z },

{ 11^x, 11^x+1 }} do

sum = sum + math.abs(j)

if math.abs(prod) < 2^27 and j~=0 then prod = prod * j end

end

print(" sum= " .. sum)

print("prod= " .. prod)</lang>

{{out}}

<pre> sum= 348173

prod= -793618560</pre>