Shifting/aligning/rotating a circular buffer to zero in-place

Question

I\'m using a circular buffer to push data onto either end of a list. After I\'m done I want to align the buffer so the first element in the list is at position zero and can be u

Answer 1

fn swapItems arr index_a index_b = (

    local item_a = arr[index_a]
    local item_b = arr[index_b]
    arr[index_a] = item_b
    arr[index_b] = item_a
),
fn rotateItems arr cnt way:#right = (

    for i=1 to cnt do ( --how many times we shift

        case way of (

            #right:(
                local next = 2
                for j=1 to arr.count-1 do ( --shift each except last

                    swapItems arr 1 next --swap first with next
                    next+=1
                )
            )
            #left:(
                local prev = arr.count - 1
                for j=arr.count to 2 by -1 do ( --shift each except first

                    swapItems arr arr.count prev --swap last with prev
                    prev-=1
                )
            )
        )
    )
)
ar = #(1, 2, 3, 4)
mcArray.rotateItems ar 1 > #(4, 1, 2, 3)
mcArray.rotateItems ar 2 > #(3, 4, 1, 2)
mcArray.rotateItems ar 1 way:#left > #(2, 3, 4, 1)