Initial data commit

Task/Loops-With-multiple-ranges/Lua/loops-with-multiple-ranges.lua

@@ -0,0 +1,32 @@
+-- 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)