auto arr1 = [1,2,3,4,5,100]; auto arr2 = [6,7,8,9,10]; foreach (ref a, b; lockstep(arr1, arr2)) { a += b; } assert(arr1 == [7,9,11,13,15,100]); /// Lockstep also supports iterating with an index variable: foreach (index, a, b; lockstep(arr1, arr2)) { assert(arr1[index] == a); assert(arr2[index] == b); }
Lockstep also supports iterating with an index variable:
auto arr1 = [0, 1, 2, 3]; auto arr2 = [4, 5, 6, 7]; size_t n = arr1.length -1; foreach_reverse (index, a, b; lockstep(arr1, arr2, StoppingPolicy.requireSameLength)) { assert(n == index); assert(index == a); assert(arr1[index] == a); assert(arr2[index] == b); n--; } auto arr3 = [4, 5]; n = 1; foreach_reverse (a, b; lockstep(arr1, arr3)) { assert(a == arr1[$-n] && b == arr3[$-n]); n++; }
Iterate multiple ranges in lockstep using a foreach loop. In contrast to zip it allows reference access to its elements. If only a single range is passed in, the Lockstep aliases itself away. If the ranges are of different lengths and s == StoppingPolicy.shortest stop after the shortest range is empty. If the ranges are of different lengths and s == StoppingPolicy.requireSameLength, throw an exception. s may not be StoppingPolicy.longest, and passing this will throw an exception.
Iterating over Lockstep in reverse and with an index is only possible when s == StoppingPolicy.requireSameLength, in order to preserve indexes. If an attempt is made at iterating in reverse when s == StoppingPolicy.shortest, an exception will be thrown.
By default StoppingPolicy is set to StoppingPolicy.shortest.
Limitations: The pure, @safe, @nogc, or nothrow attributes cannot be inferred for lockstep iteration. zip can infer the first two due to a different implementation.