samples: add Terra samples

source: https://github.com/zdevito/terra/tree/master/tests

samples/Terra/vecobj.t

@@ -0,0 +1,54 @@
+local Vec = terralib.memoize(function(typ,N)
+    N = assert(tonumber(N),"expected a number")
+    local ops = { "__sub","__add","__mul","__div" }
+    local struct VecType { 
+        data : typ[N]
+    }
+    VecType.metamethods.type, VecType.metamethods.N = typ,N
+    VecType.metamethods.__typename = function(self) return ("%s_%d"):format(tostring(self.metamethods.type),self.metamethods.N) end
+    for i, op in ipairs(ops) do
+        local i = symbol("i")
+        local function template(ae,be)
+            return quote
+                var c : VecType
+                for [i] = 0,N do
+                    c.data[i] = operator(op,ae,be)
+                end
+                return c
+            end
+        end
+        local terra doop(a : VecType, b : VecType) [template(`a.data[i],`b.data[i])]  end
+        terra doop(a : typ, b : VecType) [template(`a,`b.data[i])]  end
+        terra doop(a : VecType, b : typ) [template(`a.data[i],`b)]  end
+       VecType.metamethods[op] = doop
+    end
+    terra VecType.methods.FromConstant(x : typ)
+        var c : VecType
+        for i = 0,N do
+            c.data[i] = x
+        end
+        return c
+    end
+    VecType.metamethods.__apply = macro(function(self,idx) return `self.data[idx] end)
+    VecType.metamethods.__cast = function(from,to,exp)
+        if from:isarithmetic() and to == VecType then
+            return `VecType.FromConstant(exp)
+        end
+        error(("unknown conversion %s to %s"):format(tostring(from),tostring(to)))
+    end
+    return VecType
+end)
+
+terra foo(v : Vec(float,4), w : Vec(float,4))
+    var z : Vec(float,4) = 1
+    var x = (v*4)+w+1
+    for i = 0,4 do
+        print(x(i))
+    end
+    return x(2)
+end
+
+foo:printpretty(true,false)
+foo:disas()
+
+assert(20 == foo({{1,2,3,4}},{{5,6,7,8}}))